In a study of DNA methylation changes in melatonin-deficient rice mutants,mutant plants showed premature leaf senescence during grain-filling and reduced grain yield.Melatonin deficiency led to transcriptional reprogr...In a study of DNA methylation changes in melatonin-deficient rice mutants,mutant plants showed premature leaf senescence during grain-filling and reduced grain yield.Melatonin deficiency led to transcriptional reprogramming,especially of genes involved in chlorophyll and carbon metabolism,redox regulation,and transcriptional regulation,during dark-induced leaf senescence.Hypomethylation of mCG and mCHG in the melatonin-deficient rice mutants was associated with the expression change of both protein-coding genes and transposable element-related genes.Changes in gene expression and DNA methylation in the melatonin-deficient mutants were compensated by exogenous application of melatonin.A decreased S-adenosyl-L-methionine level may have contributed to the DNA methylation variations in rice mutants of melatonin deficiency under dark conditions.展开更多
Regulating planting density and nitrogen(N)fertilization could delay chlorophyll(Chl)degradation and leaf senescence in maize cultivars.This study measured changes in ear leaf green area(GLA_(ear)),Chl content,the act...Regulating planting density and nitrogen(N)fertilization could delay chlorophyll(Chl)degradation and leaf senescence in maize cultivars.This study measured changes in ear leaf green area(GLA_(ear)),Chl content,the activities of Chl a-degrading enzymes after silking,and the post-silking dry matter accumulation and grain yield under multiple planting densities and N fertilization rates.The dynamic change of GLA_(ear)after silking fitted to the logistic model,and the GLA_(ear) duration and the GLAearat 42 d after silking were affected mainly by the duration of the initial senescence period(T_(1))which was a key factor of the leaf senescence.The average chlorophyllase(CLH)activity was 8.3 times higher than pheophytinase activity and contributed most to the Chl content,indicating that CLH is a key enzyme for degrading Chl a in maize.Increasing density increased the CLH activity and decreased the Chl content,T1,GLAear,and GLA_(ear) duration.Under high density,appropriate N application reduced CLH activity,increased Chl content,prolonged T1,alleviated high-density-induced leaf senescence,and increased post-silking dry matter accumulation and grain yield.展开更多
Senescence-induced NAC(senNAC)TFs play a crucial role in senescence during the final stage of leaf development.In this study,we identified a rice senNAC,ONAC016,which functions as a positive regulator of leaf senescen...Senescence-induced NAC(senNAC)TFs play a crucial role in senescence during the final stage of leaf development.In this study,we identified a rice senNAC,ONAC016,which functions as a positive regulator of leaf senescence.The expression of ONAC016 increased rapidly in rice leaves during the progression of dark-induced and natural senescence.The onac016-1 knockout mutant showed a delayed leaf yellowing phenotype,whereas the overexpression of ONAC016 accelerated leaf senescence.Notably,ONAC016 expression was upregulated by abscisic acid(ABA),and thus detached leaves of the onac016-1 mutant remained green much longer under ABA treatment.Quantitative RT-PCR analysis showed that ONAC016 upregulates the genes associated with chlorophyll degradation,senescence,and ABA signaling.Yeast one-hybrid and dual-luciferase assays revealed that ONAC016 binds directly to the promoter regions of OsNAP,a key gene involved in chlorophyll degradation and ABA-induced senescence.Taken together,these results suggest that ONAC016 plays an important role in promoting leaf senescence through the ABA signaling pathway involving OsNAP.展开更多
The solar radiation intensity and duration are continuously decreasing in the major wheat planting area of China. As a con- sequence, leaf senescence, photosynthesis, grain filling and thus wheat yield shall be affect...The solar radiation intensity and duration are continuously decreasing in the major wheat planting area of China. As a con- sequence, leaf senescence, photosynthesis, grain filling and thus wheat yield shall be affected by light deficiency. Therefore, two winter wheat (Triticum aestivum L.) cultivars, Tainong 18 (a large-spike cultivar) and Ji'nan 17 (a multiple-spike cultivar), were subjected to shading during anthesis and maturity under field condition in 2010-2011 and 2011-2012. Under the slight shading treatment ($1,88% of full sunshine), leaf senescence was delayed, net photosynthesis rate (Po) and canopy apparent photosynthesis rate (CAP) were improved, and thus thousand-kernel weight (TKW) and grain yield were higher as compared with the control. However, mid and severe shading (S2 andS3, 67 and 35% of full sunshine, respectively) led to negative effects on these traits substantially. Moreover, superoxide dismutase (SOD), peroxidase (POD) and cat- alase (CAT) activities in flag leaf were significantly greater under slight shading than those in other treatments, while the malondialdehyde (MDA) content was less than that under other treatments. In addition, the multiple-spike cultivar is more tolerant to shading than large-spike cultivar. In conclusion, slight shading after anthesis delayed leaf senescence, enhanced photosynthesis and grain filling, and thus resulted in higher grain yield.展开更多
With the japonica inbred cultivar Xiushui 09, indica hybrid combinations Guodao 6 and Liangyoupeijiu as materials, field experiments were conducted in 2007 and 2008 to study the effects of aerated irrigation on leaf s...With the japonica inbred cultivar Xiushui 09, indica hybrid combinations Guodao 6 and Liangyoupeijiu as materials, field experiments were conducted in 2007 and 2008 to study the effects of aerated irrigation on leaf senescence at late growth stage and grain yield of rice. The dissolved oxygen concentration of aerated water evidently increased and decreased at a slow rate. The soil oxidation-reduction potential under aerated irrigation treatment was significantly higher than that of the CK, contributing to significant increases in effective panicles, seed setting rate and grain yield. In addition, the aerated irrigation improved root function, increased superoxide dismutase activity and decreased malondialdehyde content in flag leaves at post-flowering, which delayed leaf senescence process, prolonged leaf functional activity and led to enhanced grain filling.展开更多
Drought at the grain filling stage of wheat will cause premature leaf senescence, thus leading to considerable loss of wheat yield. Therefore, this paper aims to establish a cultivation technology for strong drought r...Drought at the grain filling stage of wheat will cause premature leaf senescence, thus leading to considerable loss of wheat yield. Therefore, this paper aims to establish a cultivation technology for strong drought resistance, delayed senescence, and yield improvement based on the analysis of hormones homeostasis obtained by applying chemical control substances. Experiments were conducted with two genotypes of wheat. Four water irrigation treatments were applied to impose the water deficit, including well-watered control treatment(WW), mild water deficit(MiWD), moderate water deficit(MoWD), and severe water deficit(SWD). Exogenous abscisic acid(ABA) was sprayed on the plants at the anthesis stage of the wheat. As a result, exogenous ABA reduced initial senescence rate(r0), total duration of chlorophyll(Chltotal), rapid senescence phase(Chlloss), and the accumulated temperature at an inflection point(M) but improved the persistence phase(Chlper) of flag leaves under all of the four treatments. However, exogenous ABA produced inconsistent effects on photoassimilate relocation and grain weight under different treatments. It produced positive regulatory effects on grain weight under WW, MiWD, and MoWD treatments. On the one hand, spraying ABA during the persistence phase of flag leaves reduced the ratios of zeatin to gibberellin(Z/GA3), spermine to spermidine(Spm/Spd), and salicylic acid to ABA(SA/ABA),which prolonged active photosynthesis by stimulating high level of proline(Pro) and increased the activities of antioxidant enzymes, such as superoxide dismutase(SOD), peroxidase(POD), catalase(CAT), and ascorbate peroxidase(APX). Therefore, drought tolerance was enhanced, and more photosynthetic assimilates were accumulated. On the other hand, the rapid senescence phase and the transport rate of assimilates into grains were accelerated, resulting in higher grain weight, yield, and water use efficiency(WUE). However, under SWD treatment, exogenous ABA improved the ratio of SA/ABA, leading to low Pro content and low antioxidant enzyme activity of flag leaves in the rapid loss phase. Meanwhile,drought resistance declined and the transport duration of assimilates into grains was shortened, thus making photosynthetic assimilates redundant. Therefore, exogenous ABA can lead to the reduction in grain weight, yield, and WUE of wheat under SWD treatment.展开更多
Leaf senescence is normally the last stage of plant development. Early senescence of functional leaves significantly reduces the photosynthetic time and efficiency, seriously affecting grain yield and quality in wheat...Leaf senescence is normally the last stage of plant development. Early senescence of functional leaves significantly reduces the photosynthetic time and efficiency, seriously affecting grain yield and quality in wheat. Discovering genes responsible for early leaf senescence(els) are necessary for developing novel germplasms and cultivars with delayed leaf-senescence through molecular manipulation and marker assisted selection. In this study, we identified an early leaf senescence line M114 in a derivative of a wheat breeding population. Genetic analysis indicated that early leaf senescence in M114 is controlled by a single recessive gene, provisionally designated els1. By applying bulked segregant analysis and RNA-Seq(BSR-Seq), seven polymorphic markers linked to els1 were developed and the gene was located on chromosome arm 2 BS in a 1.5 c M genetic interval between markers WGGB303 and WGGB305. A co-segregating marker, WGGB302, provide a starting point for fine mapping and map-based cloning of els1.展开更多
Xanthine dehydrogenase, a member of the molybdenum enzyme family, participates in purine metabolism and catalyzes the generation of ureides from xanthine and hypoxanthine. However, the mechanisms by which xanthine deh...Xanthine dehydrogenase, a member of the molybdenum enzyme family, participates in purine metabolism and catalyzes the generation of ureides from xanthine and hypoxanthine. However, the mechanisms by which xanthine dehydrogenase affects rice growth and development are poorly understood. In the present study, we identified a mutant with early leaf senescence and reduced tillering that we named early senescence and less-tillering 1(esl1). Map-based cloning revealed that ESL1 encodes a xanthine dehydrogenase, and it was expressed in all tissues. Chlorophyll content was reduced and chloroplast maldevelopment was severe in the esl1 mutant. Mutation of ESL1 led to decreases in allantoin, allantoate, and ABA contents. Further analysis revealed that the accumulation of reactive oxygen species in esl1 resulted in decreased photosynthesis and impaired chloroplast development, along with increased sensitivity to abscisic acid and abiotic stresses. Ttranscriptome analysis showed that the ESL1 mutation altered the expression of genes involved in the photosynthesis process and reactive oxygen species metabolism.Our results suggest that ESL1 is involved in purine metabolism and the induction of leaf senescence.These findings reveal novel molecular mechanisms of ESL1 gene-mediated plant growth and leaf senescence.展开更多
Two-year field experiments were conducted at Linqing, Yellow River valley of China, to study the plant response to the removal of early fruiting branches in transgenic Bt (Bacillus thuringiensis) cotton (Gossypium ...Two-year field experiments were conducted at Linqing, Yellow River valley of China, to study the plant response to the removal of early fruiting branches in transgenic Bt (Bacillus thuringiensis) cotton (Gossypium hirsutum L.) from 2003 to 2004. Plants were undamaged and treated by removing two basal fruiting branches (FB) at squaring to form the control and the removal treatment, respectively. The plant height, leaf area (LA), dry weight of fruiting forms (DWFF), the number of fruiting nodes (NFN), photosynthetic (Pn) rate, and levels of leaf chlorophyll (Chl), N, P, K, and Cry lAc protein in main- stem leaves were measured at a 10- or 20-d interval after FB removal, and the sink/source ratio as indicated by NFN/LA and DWFF/LA was determined. FB removal significantly increased the plant height, LA, and plant biomass in both years. Lint yields were increased 7.5 and 5.2% by removal compared with their controls in 2003 and 2004, respectively. Significant increases in boll size (5.7 and 5.1%) were also observed in removal than in control for both years. Either NFN/LA or DWFF/LA was significantly reduced by removal before 40 d after removal; however, both NFN/LA and DWFF/LA were significantly enhanced by FB removal at 80 d after removal compared to the untreated control. There was no significant difference in fiber quality in the first two harvests between removal and control, but fiber strength and micronarie in the third harvest were significantly improved by FB removal. In terms of leaf Chl, Pn rate, levels of total N, P, and K in late season, leaf senescence was considerably delayed by FB removal. Levels of CrylAc protein in the fully expanded young leaves were considerably higher in FB-excised plants than in control, indicating FB removal enhanced CrylAc expression. It is suggested that the yield and quality improvement with FB removal may be attributed to the increased NFN/LA or DWFF/LA in late season and delayed leaf senescence, respectively. FB removal can be a potential practice incorporated into the intensive cultivation system for enhancing transgenic Bt cotton production.展开更多
The changes of photosynthetic properties and cell microstructure in peanut leaves during leaf senescence were studied with two high-yielding peanut cultivars (cv. Luhuall and Fu8707). The main results showed that duri...The changes of photosynthetic properties and cell microstructure in peanut leaves during leaf senescence were studied with two high-yielding peanut cultivars (cv. Luhuall and Fu8707). The main results showed that during the whole process of leaf growth and senescence, changes in the photosynthesis rate (Pn) and contents of chlorophyll in leaves, could be described with a parabolic function, y = A + Bx + Cx2 (where y refers to the values of the above parameters and x to the days after leaf unfolding). During peanut leaf senescence , the shape of chloroplast changed gradually from long ellipses to circles.The starch globule in chloroplast altered gradually from more and larger sizes to fewer and smaller, but the oil globule from fewer and smaller to more and larger. The grana lamellae varied progressively: from thinness and length to thickness and shortness; from ranking along the long axle direction of chloroplast to disorderly arrangment and finally blurring. At last, the membrane envelope of chloroplast broke, so the inclusion seeped out to the cell and the chloroplast broke up.展开更多
WRKY transcription factors play essential roles during leaf senescence.However,the mechanisms by which they regulate this process remains largely unknown.Here,we identified the transcription factor WRKY75 as a positiv...WRKY transcription factors play essential roles during leaf senescence.However,the mechanisms by which they regulate this process remains largely unknown.Here,we identified the transcription factor WRKY75 as a positive regulator during leaf senescence.Mutations of WRKY75 caused a delay in agetriggered leaf senescence,whereas overexpression of WRKY75 markedly accelerated this process.Expression of senescence-associated genes(SAGs)was suppressed in WRKY75 mutants but increased in WRKY75-overexpressing plants.Further analysis demonstrated that WRKY75 directly associates with the promoters of SAG12 and SAG29,to activate their expression.Conversely,GAI and RGL1,two DELLA proteins,can suppress the WRKY75-mediated activation,thereby attenuating SAG expression during leaf senescence.Genetic analyses showed that GAI gain-of-function or RGL1 overexpression can partially rescue the accelerated senescence phenotype caused by WRKY75 overexpression.Furthermore,WRKY75 can positively regulate WRKY45 expression during leaf senescence.Our data thus imply that WRKY75 may positively modulate age-triggered leaf senescence through the gibberellin-mediated signaling pathway。展开更多
4PU—30[N—phenyl—’N—(2—chloro—4—pyridyl) urea] is a new type of plant growth regulator with cytokinin properties. It has been confirmed to delay rice leaf senescence effectively. In order to elucidate the physi...4PU—30[N—phenyl—’N—(2—chloro—4—pyridyl) urea] is a new type of plant growth regulator with cytokinin properties. It has been confirmed to delay rice leaf senescence effectively. In order to elucidate the physiological role of 4PU—30 in delaying senescence, the changes of protein, nucleic acid contents, and the related activities of degradative enzymes were studied. Shanyou 63, an indica hybrid rice was used for this experiment. In the in vitro experiment, two full—developed leaves from the top during heading stage were collected and cut into 5.0cm segments, They were floated on the surface of distilled water containing 0.1mg/14PU—30 and incubated in darkness at 30 C. The leaves floated on distilled water were used as control.It was observed that chlorophyll content in controlled leaves declined rapidly started from the second day and dropped by 93.4% on the 6th day while that in leaves treated with 4PU—30 declined by 41.4% only. During senescence, specific activities of hemoglobin—digesting展开更多
90-09 is a cmpound made with GA3,4PU-30and some trace elements(B ete.).To studythe effects of 90-09 on the leaf senescence ofhybrid rice leaf,the changes of activities ofsome degradation enzyme and the contents ofendo...90-09 is a cmpound made with GA3,4PU-30and some trace elements(B ete.).To studythe effects of 90-09 on the leaf senescence ofhybrid rice leaf,the changes of activities ofsome degradation enzyme and the contents ofendogenous hormones(ABA,ZRs,GAs,andIAA),protein,and nucleic acids were mea-sured during leaf senescence. Shanyou 63,an indica hybrid rice,wasused in this experiment.Rice plants were firstsprayed with 90-09(115 ml/hm~2) solution 10d after heading,followed by two more sprayswith once a week.The controlled plants weresprayed with water only.展开更多
Leaf senescence is an essential physiological process related to grain yield potential and nutritional quality.Green leaf duration(GLD)after anthesis directly reflects the leaf senescence process and exhibits large ge...Leaf senescence is an essential physiological process related to grain yield potential and nutritional quality.Green leaf duration(GLD)after anthesis directly reflects the leaf senescence process and exhibits large genotypic differences in common wheat;however,the underlying gene regulatory mechanism is still lacking.Here,we identified TaNAM-A1 as the causal gene of the major loci q GLD-6A for GLD during grain filling by map-based cloning.Transgenic assays and TILLING mutant analyses demonstrated that TaNAM-A1 played a critical role in regulating leaf senescence,and also affected spike length and grain size.Furthermore,the functional divergences among the three haplotypes of TaNAM-A1 were systematically evaluated.Wheat varieties with TaNAM-A1d(containing two mutations in the coding DNA sequence of TaNAM-A1)exhibited a longer GLD and superior yield-related traits compared to those with the wild type TaNAM-A1a.All three haplotypes were functional in activating the expression of genes involved in macromolecule degradation and mineral nutrient remobilization,with TaNAM-A1a showing the strongest activity and TaNAM-A1d the weakest.TaNAM-A1 also modulated the expression of the senescencerelated transcription factors TaNAC-S-7A and TaNAC016-3A.TaNAC016-3A enhanced the transcriptional activation ability of TaNAM-A1a by protein–protein interaction,thereby promoting the senescence process.Our study offers new insights into the fine-tuning of the leaf functional period and grain yield formation for wheat breeding under various geographical climatic conditions.展开更多
Most mechanistic details of chronologically ordered regulation of leaf senescence are unknown.Regulatory networks centered on AtWRKY53 are crucial for orchestrating and integrating various senescence-related signals.N...Most mechanistic details of chronologically ordered regulation of leaf senescence are unknown.Regulatory networks centered on AtWRKY53 are crucial for orchestrating and integrating various senescence-related signals.Notably,AtWRKY53binds to its own promoter and represses transcription of AtWRKY53,but the biological significance and mechanism underlying this selfrepression remain unclear.In this study,we identified the VQ motif-containing protein AtVQ25as a cooperator of AtWRKY53.The expression level of AtVQ25 peaked at mature stage and was specifically repressed after the onset of leaf senescence.AtVQ25-overexpressing plants and atvq25 mutants displayed precocious and delayed leaf senescence,respectively.Importantly,we identified AtWRKY53 as an interacting partner of AtVQ25.We determined that interaction between AtVQ25 and AtWRKY53 prevented AtWRKY53from binding to W-box elements on the AtWRKY53promoter and thus counteracted the selfrepression of AtWRKY53.In addition,our RNA-sequencing data revealed that the AtVQ25-AtWRKY53 module is related to the salicylic acid(SA)pathway.Precocious leaf senescence and SA-induced leaf senescence in AtVQ25-overexpressing lines were inhibited by an SA pathway mutant,atsid2,and Nah G transgenic plants;AtVQ25-overexpressing/atwrky53 plants were also insensitive to SA-induced leaf senescence.Collectively,we demonstrated that AtVQ25 directly attenuates the self-repression of AtWRKY53 during the onset of leaf senescence,which is substantially helpful for understanding the timing of leaf senescence onset modulated by AtWRKY53.展开更多
Plants have adopted versatile scaffold proteins to facilitate the crosstalk between multiple signaling pathways. Leaf senescence is a well-programmed developmental stage that is coordinated by various external and int...Plants have adopted versatile scaffold proteins to facilitate the crosstalk between multiple signaling pathways. Leaf senescence is a well-programmed developmental stage that is coordinated by various external and internal signals. However,the functions of plant scaffold proteins in response to senescence signals are not well understood. Here, we report that the scaffold protein RACK1A(RECEPTOR FOR ACTIVATED C KINASE1A) participates in leaf senescence mediated by ethylene signaling via the coordination of the EIN3-miR164-ORE1 transcriptional regulatory cascade. RACK1A is a novel positive regulator of ethylene-mediated leaf senescence. The rack1a mutant exhibits delayed leaf senescence, while transgenic lines overexpressing RACK1A display early leaf senescence. Moreover, RACK1A promotes EIN3(ETHYLENE INSENSITIVE 3) protein accumulation, and directly interacts with EIN3 to enhance its DNA-binding activity. Together, they then associate with the miR164 promoter to inhibit its transcription, leading to the release of the inhibition on downstream ORE1(ORESARA 1) transcription and the promotion of leaf senescence.This study reveals a mechanistic framework by which RACK1A promotes leaf senescence via the EIN3-miR164-ORE1 transcriptional cascade, and provides a paradigm for how scaffold proteins finely tune phytohormone signaling to control plant development.展开更多
Nitrogen(N)deficiency causes early leaf senescence,resulting in accelerated whole-plant maturation and severely reduced crop yield.However,the molecular mechanisms underlying N-deficiency-induced early leaf senescence...Nitrogen(N)deficiency causes early leaf senescence,resulting in accelerated whole-plant maturation and severely reduced crop yield.However,the molecular mechanisms underlying N-deficiency-induced early leaf senescence remain unclear,even in the model species Arabidopsis thaliana.In this study,we identified Growth,Development and Splicing 1(GDS1),a previously reported transcription factor,as a new regulator of nitrate(NO3)signaling by a yeast-one-hybrid screen using a NO3enhancer fragment from the promoter of NRT2.1.We showed that GDS1 promotes NO3 signaling,absorption and assimilation by affecting the expression of multiple NO3 regulatory genes,including Nitrate Regulatory Gene2(NRG2).Interestingly,we observedthat gds1mutants show early leaf senescence as well as reduced NO3-contentand Nuptake under N-deficient conditions.Further analyses indicated that GDS1 binds to the promoters of several senescence-related genes,including Phytochrome-lnteracting Transcription Factors 4 and 5(PIF4 and PIF5)and represses their expression.Interestingly,we found that N deficiency decreases GDS1 protein accumulation,and GDS1 could interact with Anaphase Promoting Complex Subunit 10(APC10).Genetic and biochemical experiments demonstrated that Anaphase Promoting Complex or Cyclosome(APC/C)promotes the ubiquitination and degradation of GDS1 under N deficiency,resulting in loss of PIF4 and PiF5 repression and consequent early leaf senescence.Furthermore,we discovered that overexpression of GDS1 could delay leaf senescence and improve seed yield and N-use efficiency(NUE)in Arabidopsis.In summary,our study uncovers a molecular framework illustrating a new mechanism underlying low-N-induced early leaf senescence and provides potential targets for genetic improvement of crop varieties with increased yield and NUE.展开更多
Leaf senescence is the final stage of leaf development and appropriate onset and progression of leaf senescence are critical for reproductive success and fitness.Although great progress has been made in identifying ke...Leaf senescence is the final stage of leaf development and appropriate onset and progression of leaf senescence are critical for reproductive success and fitness.Although great progress has been made in identifying key genes regulating leaf senescence and elucidating the underlining mechanisms in the model plant Arabidopsis,there is still a gap to understanding the complex regulatory network.In this study,we discovered that Arabidopsis ANAC087 transcription factor(TF)positively modulated leaf senescence.Expression of ANAC087 was induced in senescing leaves and the encoded protein acted as a transcriptional activator.Both constitutive and inducible overexpression lines of ANAC087 showed earlier senescence than control plants,whereas T-DNA insertion mutation and dominant repression of the ANAC087 delayed senescence rate.A quantitative reverse transcription-polymerase chain reaction(qRT-PCR)profiling showed that the expression of an array of senescence-associated genes was upregulated in inducible ANAC087 overexpression plants including BFN1,NYE1,CEP1,RbohD,SAG13,SAG15,and VPEs,which are involved in programmed cell death(PCD),chlorophyll degradation and reactive oxygen species(ROS)accumulation.In addition,electrophoretic mobility shift assay(EMSA)and chromatin immunoprecipitation-quantitative polymerase chain reaction(ChIP-qPCR)assays demonstrated that ANAC087 directly bound to the canonical NAC recognition sequence(NACRS)motif in promoters of its target genes.Moreover,mutation of two representative target genes,BFN1 or NYE1 alleviated the senescence rate of ANAC087-overexpression plants,suggesting their genetic regulatory relationship.Taken together,this study indicates that ANAC087serves as an important regulator linking PCD,ROS,and chlorophyll degradation to leaf senescence.展开更多
This paper was conducted to explore the effects of melatonin(MT)on the senescence of stored Chinese flowering cabbage and the potential modulatory mechanisms involved.The physiological findings demonstrated that MT su...This paper was conducted to explore the effects of melatonin(MT)on the senescence of stored Chinese flowering cabbage and the potential modulatory mechanisms involved.The physiological findings demonstrated that MT successfully reduced chlorophyll loss and improved the photochemical effectiveness of cabbage leaves.In addition,MT decreased the transcription of senescence-associated genes(BrSAG12)and genes responsible for chlorophyll breakdown.Transcriptome analysis showed that MT-regulated genes were enriched in oxidative phosphorylation,hormone metabolism and signal transduction,and MT treatment reduced the high expression of genes linked to generation of reactive oxygen species(ROS),energy metabolism,phytohormone(abscisic acid(ABA),ethylene(ET),and jasmonic acid(JA))biological synthesis and signal transduction while promoting the activation of genes related to scavenging ROS,energy biosynthesis and plant–pathogen interactions.We emphasized the examination of the potential interaction between phytohormone metabolism and MT.The results showed that the application of MT decreased ABA,ET,and JA levels as well as the expression of their biosynthesis genes,concurrently maintaining higher expression of cytokinin,auxin and gibberellin biosynthetic genes and lower expression of degradation genes.Regulatory networks of transcription factors(TFs)and genes related to ABA,ET and JA metabolism showed that TFs such as DNA-binding One Zinc Finger 5.7(DOF5.7),WRKY40,and homeobox-leucine zipper protein-16(ATHB-16)might play important transcriptional regulatory roles in mediating MT postponed leaf senescence.Taken together,these findings suggested that the postponed senescence of cabbage treated with MT might be ascribed to the regulated oxidative phosphorylation,energy,phytohormone metabolism,and transcription factors.展开更多
Chlorophyll (Chl) degradation is an integral process of leaf senescence, and NYE1/SGR1 has been demonstrated as a key regulator of Chl catabolism in diverse plant species. In this study, using yeast one-hybrid scree...Chlorophyll (Chl) degradation is an integral process of leaf senescence, and NYE1/SGR1 has been demonstrated as a key regulator of Chl catabolism in diverse plant species. In this study, using yeast one-hybrid screening, we identified three abscisic acid (ABA)-responsive element (ABRE)-binding transcription factors, ABF2 (AREB1), ABF3, and ABF4 (AREB2), as the putative binding proteins of the NYE1 promoter. Through the transactivation analysis, electrophoretic mobility shift assay, and chromatin immunoprecipitation, we demonstrated that ABF2, ABF3, and ABF4 directly bound to and activated the NYE1 promoter in vitro and in vivo. ABA is a positive regulator of leaf senescence, and exogenously applied ABA can accelerate Chl degradation. The triple mutant of the ABFs, abf2abf3abf4, as well as two ABA-insensitive mutants, abil-1 and snrk2.2/2.3/2.6, exhibited stay-green phenotypes after ABA treatment, along with decreased induction of NYE1 and NYE2 expression. In contrast, overexpression of ABF4 accelerated Chl degradation upon ABA treatment. Interestingly, ABF2/3/4 could also activate the expression of two Chl catabolic enzyme genes, PAO and NYCl, by directly binding to their promoters. In addition, abf2abf3abf4 exhibited a functional stay-green phenotype, and senescence-associated genes (SAGs), such as SAG29 (SWEET15), might be directly regulated by the ABFs. Taken together, our results suggest that ABF2, ABF3, and ABF4 likely act as key regulators in mediating ABA-triggered Chl degradation and leaf senescence in general in Arabidopsis.展开更多
基金supported by the National Natural Science Foundation of China(32100448,32070558,32061143030,32170636)Natural Science Foundation of Jiangsu Province(BK20210799)+2 种基金Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),the Seed Industry Revitalization Project of Jiangsu Province(JBGS[2021]009)the Shanghai Science and Technology Agriculture Project([2022]No.1–6)the Project of Zhongshan Biological Breeding Laboratory(BM2022008-029)。
文摘In a study of DNA methylation changes in melatonin-deficient rice mutants,mutant plants showed premature leaf senescence during grain-filling and reduced grain yield.Melatonin deficiency led to transcriptional reprogramming,especially of genes involved in chlorophyll and carbon metabolism,redox regulation,and transcriptional regulation,during dark-induced leaf senescence.Hypomethylation of mCG and mCHG in the melatonin-deficient rice mutants was associated with the expression change of both protein-coding genes and transposable element-related genes.Changes in gene expression and DNA methylation in the melatonin-deficient mutants were compensated by exogenous application of melatonin.A decreased S-adenosyl-L-methionine level may have contributed to the DNA methylation variations in rice mutants of melatonin deficiency under dark conditions.
基金financially supported by the National Key Research and Development Program of China(2022YFD190160304)Natural Science Foundation of Sichuan Province(2022NSFSC0013)+1 种基金Sichuan Maize Innovation Team Construction Project(SCCXTD-2022-02)National Key Research and Development Program of China(2018YFD0301206)。
文摘Regulating planting density and nitrogen(N)fertilization could delay chlorophyll(Chl)degradation and leaf senescence in maize cultivars.This study measured changes in ear leaf green area(GLA_(ear)),Chl content,the activities of Chl a-degrading enzymes after silking,and the post-silking dry matter accumulation and grain yield under multiple planting densities and N fertilization rates.The dynamic change of GLA_(ear)after silking fitted to the logistic model,and the GLA_(ear) duration and the GLAearat 42 d after silking were affected mainly by the duration of the initial senescence period(T_(1))which was a key factor of the leaf senescence.The average chlorophyllase(CLH)activity was 8.3 times higher than pheophytinase activity and contributed most to the Chl content,indicating that CLH is a key enzyme for degrading Chl a in maize.Increasing density increased the CLH activity and decreased the Chl content,T1,GLAear,and GLA_(ear) duration.Under high density,appropriate N application reduced CLH activity,increased Chl content,prolonged T1,alleviated high-density-induced leaf senescence,and increased post-silking dry matter accumulation and grain yield.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(2022R1A2C1091553 to Nam-Chon Paek and 2022R1F1A1075022 to Kiyoon Kang)。
文摘Senescence-induced NAC(senNAC)TFs play a crucial role in senescence during the final stage of leaf development.In this study,we identified a rice senNAC,ONAC016,which functions as a positive regulator of leaf senescence.The expression of ONAC016 increased rapidly in rice leaves during the progression of dark-induced and natural senescence.The onac016-1 knockout mutant showed a delayed leaf yellowing phenotype,whereas the overexpression of ONAC016 accelerated leaf senescence.Notably,ONAC016 expression was upregulated by abscisic acid(ABA),and thus detached leaves of the onac016-1 mutant remained green much longer under ABA treatment.Quantitative RT-PCR analysis showed that ONAC016 upregulates the genes associated with chlorophyll degradation,senescence,and ABA signaling.Yeast one-hybrid and dual-luciferase assays revealed that ONAC016 binds directly to the promoter regions of OsNAP,a key gene involved in chlorophyll degradation and ABA-induced senescence.Taken together,these results suggest that ONAC016 plays an important role in promoting leaf senescence through the ABA signaling pathway involving OsNAP.
基金supported by the National Natural Science Foundation of China (31271661)the Special Fund for Agro-scientific Research in the Public Interest of China (201203100, 201203031)
文摘The solar radiation intensity and duration are continuously decreasing in the major wheat planting area of China. As a con- sequence, leaf senescence, photosynthesis, grain filling and thus wheat yield shall be affected by light deficiency. Therefore, two winter wheat (Triticum aestivum L.) cultivars, Tainong 18 (a large-spike cultivar) and Ji'nan 17 (a multiple-spike cultivar), were subjected to shading during anthesis and maturity under field condition in 2010-2011 and 2011-2012. Under the slight shading treatment ($1,88% of full sunshine), leaf senescence was delayed, net photosynthesis rate (Po) and canopy apparent photosynthesis rate (CAP) were improved, and thus thousand-kernel weight (TKW) and grain yield were higher as compared with the control. However, mid and severe shading (S2 andS3, 67 and 35% of full sunshine, respectively) led to negative effects on these traits substantially. Moreover, superoxide dismutase (SOD), peroxidase (POD) and cat- alase (CAT) activities in flag leaf were significantly greater under slight shading than those in other treatments, while the malondialdehyde (MDA) content was less than that under other treatments. In addition, the multiple-spike cultivar is more tolerant to shading than large-spike cultivar. In conclusion, slight shading after anthesis delayed leaf senescence, enhanced photosynthesis and grain filling, and thus resulted in higher grain yield.
文摘With the japonica inbred cultivar Xiushui 09, indica hybrid combinations Guodao 6 and Liangyoupeijiu as materials, field experiments were conducted in 2007 and 2008 to study the effects of aerated irrigation on leaf senescence at late growth stage and grain yield of rice. The dissolved oxygen concentration of aerated water evidently increased and decreased at a slow rate. The soil oxidation-reduction potential under aerated irrigation treatment was significantly higher than that of the CK, contributing to significant increases in effective panicles, seed setting rate and grain yield. In addition, the aerated irrigation improved root function, increased superoxide dismutase activity and decreased malondialdehyde content in flag leaves at post-flowering, which delayed leaf senescence process, prolonged leaf functional activity and led to enhanced grain filling.
基金supported by the National Key Research and Development Program of China(grant Nos.:2017YFD0301001 and 2016YFD0300403)the Shandong Province Mount Tai Industrial Talents Programthe National Natural Science Foundation of China(grant No.:31801295)。
文摘Drought at the grain filling stage of wheat will cause premature leaf senescence, thus leading to considerable loss of wheat yield. Therefore, this paper aims to establish a cultivation technology for strong drought resistance, delayed senescence, and yield improvement based on the analysis of hormones homeostasis obtained by applying chemical control substances. Experiments were conducted with two genotypes of wheat. Four water irrigation treatments were applied to impose the water deficit, including well-watered control treatment(WW), mild water deficit(MiWD), moderate water deficit(MoWD), and severe water deficit(SWD). Exogenous abscisic acid(ABA) was sprayed on the plants at the anthesis stage of the wheat. As a result, exogenous ABA reduced initial senescence rate(r0), total duration of chlorophyll(Chltotal), rapid senescence phase(Chlloss), and the accumulated temperature at an inflection point(M) but improved the persistence phase(Chlper) of flag leaves under all of the four treatments. However, exogenous ABA produced inconsistent effects on photoassimilate relocation and grain weight under different treatments. It produced positive regulatory effects on grain weight under WW, MiWD, and MoWD treatments. On the one hand, spraying ABA during the persistence phase of flag leaves reduced the ratios of zeatin to gibberellin(Z/GA3), spermine to spermidine(Spm/Spd), and salicylic acid to ABA(SA/ABA),which prolonged active photosynthesis by stimulating high level of proline(Pro) and increased the activities of antioxidant enzymes, such as superoxide dismutase(SOD), peroxidase(POD), catalase(CAT), and ascorbate peroxidase(APX). Therefore, drought tolerance was enhanced, and more photosynthetic assimilates were accumulated. On the other hand, the rapid senescence phase and the transport rate of assimilates into grains were accelerated, resulting in higher grain weight, yield, and water use efficiency(WUE). However, under SWD treatment, exogenous ABA improved the ratio of SA/ABA, leading to low Pro content and low antioxidant enzyme activity of flag leaves in the rapid loss phase. Meanwhile,drought resistance declined and the transport duration of assimilates into grains was shortened, thus making photosynthetic assimilates redundant. Therefore, exogenous ABA can lead to the reduction in grain weight, yield, and WUE of wheat under SWD treatment.
基金supported by the National Key Research and Development Program of China(2017YFD0101004)Science and Technology Service Network Initiative of Chinese Academy of Sciences(KFJ-STSZDTP-024)
文摘Leaf senescence is normally the last stage of plant development. Early senescence of functional leaves significantly reduces the photosynthetic time and efficiency, seriously affecting grain yield and quality in wheat. Discovering genes responsible for early leaf senescence(els) are necessary for developing novel germplasms and cultivars with delayed leaf-senescence through molecular manipulation and marker assisted selection. In this study, we identified an early leaf senescence line M114 in a derivative of a wheat breeding population. Genetic analysis indicated that early leaf senescence in M114 is controlled by a single recessive gene, provisionally designated els1. By applying bulked segregant analysis and RNA-Seq(BSR-Seq), seven polymorphic markers linked to els1 were developed and the gene was located on chromosome arm 2 BS in a 1.5 c M genetic interval between markers WGGB303 and WGGB305. A co-segregating marker, WGGB302, provide a starting point for fine mapping and map-based cloning of els1.
基金supported by the Key Transgenic Breeding Program of the Ministry of Agriculture and Rural Affairs of China(2016ZX08009003-003-008)the National Natural Science Foundation of China(31971921,U20A2030)the State Key Laboratory of Rice Biology,China(20200102)。
文摘Xanthine dehydrogenase, a member of the molybdenum enzyme family, participates in purine metabolism and catalyzes the generation of ureides from xanthine and hypoxanthine. However, the mechanisms by which xanthine dehydrogenase affects rice growth and development are poorly understood. In the present study, we identified a mutant with early leaf senescence and reduced tillering that we named early senescence and less-tillering 1(esl1). Map-based cloning revealed that ESL1 encodes a xanthine dehydrogenase, and it was expressed in all tissues. Chlorophyll content was reduced and chloroplast maldevelopment was severe in the esl1 mutant. Mutation of ESL1 led to decreases in allantoin, allantoate, and ABA contents. Further analysis revealed that the accumulation of reactive oxygen species in esl1 resulted in decreased photosynthesis and impaired chloroplast development, along with increased sensitivity to abscisic acid and abiotic stresses. Ttranscriptome analysis showed that the ESL1 mutation altered the expression of genes involved in the photosynthesis process and reactive oxygen species metabolism.Our results suggest that ESL1 is involved in purine metabolism and the induction of leaf senescence.These findings reveal novel molecular mechanisms of ESL1 gene-mediated plant growth and leaf senescence.
文摘Two-year field experiments were conducted at Linqing, Yellow River valley of China, to study the plant response to the removal of early fruiting branches in transgenic Bt (Bacillus thuringiensis) cotton (Gossypium hirsutum L.) from 2003 to 2004. Plants were undamaged and treated by removing two basal fruiting branches (FB) at squaring to form the control and the removal treatment, respectively. The plant height, leaf area (LA), dry weight of fruiting forms (DWFF), the number of fruiting nodes (NFN), photosynthetic (Pn) rate, and levels of leaf chlorophyll (Chl), N, P, K, and Cry lAc protein in main- stem leaves were measured at a 10- or 20-d interval after FB removal, and the sink/source ratio as indicated by NFN/LA and DWFF/LA was determined. FB removal significantly increased the plant height, LA, and plant biomass in both years. Lint yields were increased 7.5 and 5.2% by removal compared with their controls in 2003 and 2004, respectively. Significant increases in boll size (5.7 and 5.1%) were also observed in removal than in control for both years. Either NFN/LA or DWFF/LA was significantly reduced by removal before 40 d after removal; however, both NFN/LA and DWFF/LA were significantly enhanced by FB removal at 80 d after removal compared to the untreated control. There was no significant difference in fiber quality in the first two harvests between removal and control, but fiber strength and micronarie in the third harvest were significantly improved by FB removal. In terms of leaf Chl, Pn rate, levels of total N, P, and K in late season, leaf senescence was considerably delayed by FB removal. Levels of CrylAc protein in the fully expanded young leaves were considerably higher in FB-excised plants than in control, indicating FB removal enhanced CrylAc expression. It is suggested that the yield and quality improvement with FB removal may be attributed to the increased NFN/LA or DWFF/LA in late season and delayed leaf senescence, respectively. FB removal can be a potential practice incorporated into the intensive cultivation system for enhancing transgenic Bt cotton production.
基金supported by the Reward Fund of Outstanding Youth and Middle Age Scientist of Shandong Province(9908)the Doctor Fund of Shandong Agricultural University.
文摘The changes of photosynthetic properties and cell microstructure in peanut leaves during leaf senescence were studied with two high-yielding peanut cultivars (cv. Luhuall and Fu8707). The main results showed that during the whole process of leaf growth and senescence, changes in the photosynthesis rate (Pn) and contents of chlorophyll in leaves, could be described with a parabolic function, y = A + Bx + Cx2 (where y refers to the values of the above parameters and x to the days after leaf unfolding). During peanut leaf senescence , the shape of chloroplast changed gradually from long ellipses to circles.The starch globule in chloroplast altered gradually from more and larger sizes to fewer and smaller, but the oil globule from fewer and smaller to more and larger. The grana lamellae varied progressively: from thinness and length to thickness and shortness; from ranking along the long axle direction of chloroplast to disorderly arrangment and finally blurring. At last, the membrane envelope of chloroplast broke, so the inclusion seeped out to the cell and the chloroplast broke up.
基金the National Key R&D Plan(2016YFD0101006)Natural Science Foundation of China(31671275)Yunnan Fundamental Research Projects(2019FA010)。
文摘WRKY transcription factors play essential roles during leaf senescence.However,the mechanisms by which they regulate this process remains largely unknown.Here,we identified the transcription factor WRKY75 as a positive regulator during leaf senescence.Mutations of WRKY75 caused a delay in agetriggered leaf senescence,whereas overexpression of WRKY75 markedly accelerated this process.Expression of senescence-associated genes(SAGs)was suppressed in WRKY75 mutants but increased in WRKY75-overexpressing plants.Further analysis demonstrated that WRKY75 directly associates with the promoters of SAG12 and SAG29,to activate their expression.Conversely,GAI and RGL1,two DELLA proteins,can suppress the WRKY75-mediated activation,thereby attenuating SAG expression during leaf senescence.Genetic analyses showed that GAI gain-of-function or RGL1 overexpression can partially rescue the accelerated senescence phenotype caused by WRKY75 overexpression.Furthermore,WRKY75 can positively regulate WRKY45 expression during leaf senescence.Our data thus imply that WRKY75 may positively modulate age-triggered leaf senescence through the gibberellin-mediated signaling pathway。
文摘4PU—30[N—phenyl—’N—(2—chloro—4—pyridyl) urea] is a new type of plant growth regulator with cytokinin properties. It has been confirmed to delay rice leaf senescence effectively. In order to elucidate the physiological role of 4PU—30 in delaying senescence, the changes of protein, nucleic acid contents, and the related activities of degradative enzymes were studied. Shanyou 63, an indica hybrid rice was used for this experiment. In the in vitro experiment, two full—developed leaves from the top during heading stage were collected and cut into 5.0cm segments, They were floated on the surface of distilled water containing 0.1mg/14PU—30 and incubated in darkness at 30 C. The leaves floated on distilled water were used as control.It was observed that chlorophyll content in controlled leaves declined rapidly started from the second day and dropped by 93.4% on the 6th day while that in leaves treated with 4PU—30 declined by 41.4% only. During senescence, specific activities of hemoglobin—digesting
文摘90-09 is a cmpound made with GA3,4PU-30and some trace elements(B ete.).To studythe effects of 90-09 on the leaf senescence ofhybrid rice leaf,the changes of activities ofsome degradation enzyme and the contents ofendogenous hormones(ABA,ZRs,GAs,andIAA),protein,and nucleic acids were mea-sured during leaf senescence. Shanyou 63,an indica hybrid rice,wasused in this experiment.Rice plants were firstsprayed with 90-09(115 ml/hm~2) solution 10d after heading,followed by two more sprayswith once a week.The controlled plants weresprayed with water only.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA24010202)the National Natural Sciences Foundation of China(U22A6009)。
文摘Leaf senescence is an essential physiological process related to grain yield potential and nutritional quality.Green leaf duration(GLD)after anthesis directly reflects the leaf senescence process and exhibits large genotypic differences in common wheat;however,the underlying gene regulatory mechanism is still lacking.Here,we identified TaNAM-A1 as the causal gene of the major loci q GLD-6A for GLD during grain filling by map-based cloning.Transgenic assays and TILLING mutant analyses demonstrated that TaNAM-A1 played a critical role in regulating leaf senescence,and also affected spike length and grain size.Furthermore,the functional divergences among the three haplotypes of TaNAM-A1 were systematically evaluated.Wheat varieties with TaNAM-A1d(containing two mutations in the coding DNA sequence of TaNAM-A1)exhibited a longer GLD and superior yield-related traits compared to those with the wild type TaNAM-A1a.All three haplotypes were functional in activating the expression of genes involved in macromolecule degradation and mineral nutrient remobilization,with TaNAM-A1a showing the strongest activity and TaNAM-A1d the weakest.TaNAM-A1 also modulated the expression of the senescencerelated transcription factors TaNAC-S-7A and TaNAC016-3A.TaNAC016-3A enhanced the transcriptional activation ability of TaNAM-A1a by protein–protein interaction,thereby promoting the senescence process.Our study offers new insights into the fine-tuning of the leaf functional period and grain yield formation for wheat breeding under various geographical climatic conditions.
基金supported by grants from the National Natural Science Foundation of China(31970199)the Natural Science Fund for Distinguished Young Scholars of Hebei Province(C2022205015)+2 种基金the Central Government Guides Local Science and Technology Development Project(216Z2901G)the S&T Program of Hebei(21322915D)the Natural Science Foundation of Hebei Province(C2022205038,C2021205013,and C2023205049)。
文摘Most mechanistic details of chronologically ordered regulation of leaf senescence are unknown.Regulatory networks centered on AtWRKY53 are crucial for orchestrating and integrating various senescence-related signals.Notably,AtWRKY53binds to its own promoter and represses transcription of AtWRKY53,but the biological significance and mechanism underlying this selfrepression remain unclear.In this study,we identified the VQ motif-containing protein AtVQ25as a cooperator of AtWRKY53.The expression level of AtVQ25 peaked at mature stage and was specifically repressed after the onset of leaf senescence.AtVQ25-overexpressing plants and atvq25 mutants displayed precocious and delayed leaf senescence,respectively.Importantly,we identified AtWRKY53 as an interacting partner of AtVQ25.We determined that interaction between AtVQ25 and AtWRKY53 prevented AtWRKY53from binding to W-box elements on the AtWRKY53promoter and thus counteracted the selfrepression of AtWRKY53.In addition,our RNA-sequencing data revealed that the AtVQ25-AtWRKY53 module is related to the salicylic acid(SA)pathway.Precocious leaf senescence and SA-induced leaf senescence in AtVQ25-overexpressing lines were inhibited by an SA pathway mutant,atsid2,and Nah G transgenic plants;AtVQ25-overexpressing/atwrky53 plants were also insensitive to SA-induced leaf senescence.Collectively,we demonstrated that AtVQ25 directly attenuates the self-repression of AtWRKY53 during the onset of leaf senescence,which is substantially helpful for understanding the timing of leaf senescence onset modulated by AtWRKY53.
基金supported by grants from the National Natural Science Foundation of China (32070292 to J.L.)Shenzhen Science and Technology Program (KQTD2019 0929173906742 to J.L.)+1 种基金The Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes (2019KSYS006 to J.L.)Scientific Research Funding for postdoctoral researchers staying at Shenzhen (K19227561, K21227504 to W.Z.)。
文摘Plants have adopted versatile scaffold proteins to facilitate the crosstalk between multiple signaling pathways. Leaf senescence is a well-programmed developmental stage that is coordinated by various external and internal signals. However,the functions of plant scaffold proteins in response to senescence signals are not well understood. Here, we report that the scaffold protein RACK1A(RECEPTOR FOR ACTIVATED C KINASE1A) participates in leaf senescence mediated by ethylene signaling via the coordination of the EIN3-miR164-ORE1 transcriptional regulatory cascade. RACK1A is a novel positive regulator of ethylene-mediated leaf senescence. The rack1a mutant exhibits delayed leaf senescence, while transgenic lines overexpressing RACK1A display early leaf senescence. Moreover, RACK1A promotes EIN3(ETHYLENE INSENSITIVE 3) protein accumulation, and directly interacts with EIN3 to enhance its DNA-binding activity. Together, they then associate with the miR164 promoter to inhibit its transcription, leading to the release of the inhibition on downstream ORE1(ORESARA 1) transcription and the promotion of leaf senescence.This study reveals a mechanistic framework by which RACK1A promotes leaf senescence via the EIN3-miR164-ORE1 transcriptional cascade, and provides a paradigm for how scaffold proteins finely tune phytohormone signaling to control plant development.
基金supported by grants from the National Natural Science Foundation of China(grant no.31970270)Y.W.,the Taishan Scholar Foundation to Y.W.,the National Research and Development Program of China(2021YFF1000401)+1 种基金Y.W.,and the National Natural Science Foundation of China(grant no.32200228)the Natural Science Foundation of Shandong Province(grant no.ZR2020QC028)to H.F.
文摘Nitrogen(N)deficiency causes early leaf senescence,resulting in accelerated whole-plant maturation and severely reduced crop yield.However,the molecular mechanisms underlying N-deficiency-induced early leaf senescence remain unclear,even in the model species Arabidopsis thaliana.In this study,we identified Growth,Development and Splicing 1(GDS1),a previously reported transcription factor,as a new regulator of nitrate(NO3)signaling by a yeast-one-hybrid screen using a NO3enhancer fragment from the promoter of NRT2.1.We showed that GDS1 promotes NO3 signaling,absorption and assimilation by affecting the expression of multiple NO3 regulatory genes,including Nitrate Regulatory Gene2(NRG2).Interestingly,we observedthat gds1mutants show early leaf senescence as well as reduced NO3-contentand Nuptake under N-deficient conditions.Further analyses indicated that GDS1 binds to the promoters of several senescence-related genes,including Phytochrome-lnteracting Transcription Factors 4 and 5(PIF4 and PIF5)and represses their expression.Interestingly,we found that N deficiency decreases GDS1 protein accumulation,and GDS1 could interact with Anaphase Promoting Complex Subunit 10(APC10).Genetic and biochemical experiments demonstrated that Anaphase Promoting Complex or Cyclosome(APC/C)promotes the ubiquitination and degradation of GDS1 under N deficiency,resulting in loss of PIF4 and PiF5 repression and consequent early leaf senescence.Furthermore,we discovered that overexpression of GDS1 could delay leaf senescence and improve seed yield and N-use efficiency(NUE)in Arabidopsis.In summary,our study uncovers a molecular framework illustrating a new mechanism underlying low-N-induced early leaf senescence and provides potential targets for genetic improvement of crop varieties with increased yield and NUE.
基金supported by the National Natural Science Foundation of China(32171953 to B.Y.and 32101782 to J.Y.)the Fundamental Research Funds for the Central Universities(2452017025 to Y.Q.J.)。
文摘Leaf senescence is the final stage of leaf development and appropriate onset and progression of leaf senescence are critical for reproductive success and fitness.Although great progress has been made in identifying key genes regulating leaf senescence and elucidating the underlining mechanisms in the model plant Arabidopsis,there is still a gap to understanding the complex regulatory network.In this study,we discovered that Arabidopsis ANAC087 transcription factor(TF)positively modulated leaf senescence.Expression of ANAC087 was induced in senescing leaves and the encoded protein acted as a transcriptional activator.Both constitutive and inducible overexpression lines of ANAC087 showed earlier senescence than control plants,whereas T-DNA insertion mutation and dominant repression of the ANAC087 delayed senescence rate.A quantitative reverse transcription-polymerase chain reaction(qRT-PCR)profiling showed that the expression of an array of senescence-associated genes was upregulated in inducible ANAC087 overexpression plants including BFN1,NYE1,CEP1,RbohD,SAG13,SAG15,and VPEs,which are involved in programmed cell death(PCD),chlorophyll degradation and reactive oxygen species(ROS)accumulation.In addition,electrophoretic mobility shift assay(EMSA)and chromatin immunoprecipitation-quantitative polymerase chain reaction(ChIP-qPCR)assays demonstrated that ANAC087 directly bound to the canonical NAC recognition sequence(NACRS)motif in promoters of its target genes.Moreover,mutation of two representative target genes,BFN1 or NYE1 alleviated the senescence rate of ANAC087-overexpression plants,suggesting their genetic regulatory relationship.Taken together,this study indicates that ANAC087serves as an important regulator linking PCD,ROS,and chlorophyll degradation to leaf senescence.
基金This work was funded by the National Natural Science Foundation of Hunan Province(No.2021JJ40534)the Scientific Research Foundation for Doctors of Xiangtan University(No.20QDZ16),China.
文摘This paper was conducted to explore the effects of melatonin(MT)on the senescence of stored Chinese flowering cabbage and the potential modulatory mechanisms involved.The physiological findings demonstrated that MT successfully reduced chlorophyll loss and improved the photochemical effectiveness of cabbage leaves.In addition,MT decreased the transcription of senescence-associated genes(BrSAG12)and genes responsible for chlorophyll breakdown.Transcriptome analysis showed that MT-regulated genes were enriched in oxidative phosphorylation,hormone metabolism and signal transduction,and MT treatment reduced the high expression of genes linked to generation of reactive oxygen species(ROS),energy metabolism,phytohormone(abscisic acid(ABA),ethylene(ET),and jasmonic acid(JA))biological synthesis and signal transduction while promoting the activation of genes related to scavenging ROS,energy biosynthesis and plant–pathogen interactions.We emphasized the examination of the potential interaction between phytohormone metabolism and MT.The results showed that the application of MT decreased ABA,ET,and JA levels as well as the expression of their biosynthesis genes,concurrently maintaining higher expression of cytokinin,auxin and gibberellin biosynthetic genes and lower expression of degradation genes.Regulatory networks of transcription factors(TFs)and genes related to ABA,ET and JA metabolism showed that TFs such as DNA-binding One Zinc Finger 5.7(DOF5.7),WRKY40,and homeobox-leucine zipper protein-16(ATHB-16)might play important transcriptional regulatory roles in mediating MT postponed leaf senescence.Taken together,these findings suggested that the postponed senescence of cabbage treated with MT might be ascribed to the regulated oxidative phosphorylation,energy,phytohormone metabolism,and transcription factors.
文摘Chlorophyll (Chl) degradation is an integral process of leaf senescence, and NYE1/SGR1 has been demonstrated as a key regulator of Chl catabolism in diverse plant species. In this study, using yeast one-hybrid screening, we identified three abscisic acid (ABA)-responsive element (ABRE)-binding transcription factors, ABF2 (AREB1), ABF3, and ABF4 (AREB2), as the putative binding proteins of the NYE1 promoter. Through the transactivation analysis, electrophoretic mobility shift assay, and chromatin immunoprecipitation, we demonstrated that ABF2, ABF3, and ABF4 directly bound to and activated the NYE1 promoter in vitro and in vivo. ABA is a positive regulator of leaf senescence, and exogenously applied ABA can accelerate Chl degradation. The triple mutant of the ABFs, abf2abf3abf4, as well as two ABA-insensitive mutants, abil-1 and snrk2.2/2.3/2.6, exhibited stay-green phenotypes after ABA treatment, along with decreased induction of NYE1 and NYE2 expression. In contrast, overexpression of ABF4 accelerated Chl degradation upon ABA treatment. Interestingly, ABF2/3/4 could also activate the expression of two Chl catabolic enzyme genes, PAO and NYCl, by directly binding to their promoters. In addition, abf2abf3abf4 exhibited a functional stay-green phenotype, and senescence-associated genes (SAGs), such as SAG29 (SWEET15), might be directly regulated by the ABFs. Taken together, our results suggest that ABF2, ABF3, and ABF4 likely act as key regulators in mediating ABA-triggered Chl degradation and leaf senescence in general in Arabidopsis.