GA Associated Dwarf 5 encodes an ent-kaurenoic acid oxidase required for maize gibberellin biosynthesis and morphogenesis

Gibberellin(GA)functions in plant growth and development.However,genes involved in the biosynthesis and regulation of GA in crop plants are poorly understood.We isolated the mutant gad5-1(GAAssociated Dwarf 5),characterized by dwarfing,short internodes,and dark green and short leaves.Map-based gene cloning and allelic verification confirmed that ZmGAD5 encodes ent-kaurenoic acid oxidase(KAO),which catalyzes KA(ent-kaurenoic acid)to GA12 conversion during GA biosynthesis in maize.ZmGAD5 is localized to the endoplasmic reticulum and is present in multiple maize organs.In gad5-1,the expression of ZmGAD5 is severely reduced,and the levels of the direct substrate of KAO,KA,is increased,leading to a reduction in GA content.The abnormal phenotype of gad5-1 was restored by exogenous application of GA3.The biomass,plant height,and levels of GA12 and GA3 in transgenic Arabidopsis overexpressing ZmGAD5 were increased in comparison with the corresponding controls Col-0.These findings deepen our understanding of genes involved in GA biosynthesis,and could lead to the development of maize lines with improved architecture and higher planting-density tolerance.

How plants sense and respond to osmotic stress

Drought is one of the most serious abiotic stresses to land plants.Plants sense and respond to drought stress to survive under water deficiency.Scientists have studied how plants sense drought stress,or osmotic stress caused by drought,ever since Charles Darwin,and gradually obtained clues about osmotic stress sensing and signaling in plants.Osmotic stress is a physical stimulus that triggers many physiological changes at the cellular level,including changes in turgor,cell wall stiffness and integrity,membrane tension,and cell fluid volume,and plants may sense some of these stimuli and trigger downstream responses.In this review,we emphasized water potential and movements in organisms,compared putative signal inputs in cell wall-containing and cell wall-free organisms,prospected how plants sense changes in turgor,membrane tension,and cell fluid volume under osmotic stress according to advances in plants,animals,yeasts,and bacteria,summarized multilevel biochemical and physiological signal outputs,such as plasma membrane nanodomain formation,membrane water permeability,root hydrotropism,root halotropism,Casparian strip and suberin lamellae,and finally proposed a hypothesis that osmotic stress responses are likely to be a cocktail of signaling mediated by multiple osmosensors.We also discussed the core scientific questions,provided perspective about the future directions in this field,and highlighted the importance of robust and smart root systems and efficient source-sink allocations for generating future high-yield stress-resistant crops and plants.

Global characterization of OsPIP aquaporins reveals that the H_(2)O_(2)transporter OsPIP2;6 increases resistance to rice blast

Plasma membrane intrinsic proteins(PIPs)are conserved plant aquaporins that transport small molecules across the plasma membrane to trigger instant stress responses and maintain cellular homeostasis under biotic and abiotic stress.To elucidate their roles in plant immunity to pathogen attack,we characterized the expression patterns,subcellular localizations,and H_(2)O_(2)-transport ability of 11 OsPIPs in rice(Oryza sativa),and identified OsPIP2;6 as necessary for rice disease resistance.OsPIP2;6 resides on the plasma membrane and facilitates cytoplasmic import of the immune signaling molecule H_(2)O_(2).Knockout of OsPIP2;6 increases rice susceptibility to Magnaporthe oryzae,indicating a positive function in plant immunity.OsPIP2;6 interacts with OsPIP2;2,which has been reported to increase rice resistance to pathogens via H_(2)O_(2)transport.Our findings suggest that OsPIP2;6 cooperates with OsPIP2;2 as a defense signal transporter complex during plant–pathogen interaction.

Spatial distribution of bolls affects yield formation in different genotypes of Bt cotton varieties

To optimize the spatial distribution of cotton bolls and to increase the yield,the relationship between yield components and boll spatial distribution was investigated among different Bt(Bacillus thuringensis)cotton varieties.A five-year field experiment was conducted to reveal the reasons for the differences in lint yield and fiber quality across three Bt cotton varieties with different yield formations from 2013 to 2017.The lint yield of Jiman 169(the average yield from 2013-2017 was 42.2 g/plant)was the highest,i.e.,16.3 and 36.9%higher than Lumianyan 21(L21)and Daizimian 99B(99B),respectively.And the differences in boll weight among the three cultivars were similar to the lint yield,while the others yield components were not.So the increase in lint yield was mainly attributed to the enlargement in boll weight.However,the change in fiber quality was inconsistent with the lint yield,and the quality of L21 was significantly better than that of Jimian 169(J169)and 99B,which was caused by the diversity of boll spatial distribution.Compared with 99B,the loose-type J169 had the highest number of large bolls in inner positions;the tight-type L21 had a few large bolls and the highest number of lower and middle bolls.And approximately 80.72%of the lint yield was concentrated on the inner nodes in Jiman 169,compared with 77.44%of L21 and 66.73%of 99B during the five-year experiment.Although lint yield was significantly affected by the interannual changes,the lint yield of J169 was the highest and the most stable,as well as its yield components.These observations demonstrated the increase in lint yield was due to the increase in boll weight,and the large bolls and high fiber quality were attributed to the optimal distribution of bolls within the canopies.

Genome editing for horticultural crop improvement

Horticultural crops provide humans with many valuable products.The improvement of the yield and quality of horticultural crops has been receiving increasing research attention.Given the development and advantages of genome-editing technologies,research that uses genome editing to improve horticultural crops has substantially increased in recent years.Here,we briefly review the different genome-editing systems used in horticultural research with a focus on clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated 9(Cas9)-mediated genome editing.We also summarize recent progress in the application of genome editing for horticultural crop improvement.The combination of rapidly advancing genome-editing technology with breeding will greatly increase horticultural crop production and quality.

Increasing grain weight and yield stability by increasing pre-heading non-structural carbohydrate reserves per spikelet in short-growth duration rice

Rice yield stability is a breeding goal,particularly for short-growth duration rice,but its underlying mechanisms remain unclear.In an attempt to identify the relationship between yield stability and source–sink characteristics in short-growth duration rice,a field experiment was conducted at three sites(Yueyang,Liuyang,and Hengyang)in 2021 and 2022.This study compared yield,yield components,source–sink characteristics,and their stability between two stable-yielding short-growth duration rice cultivars,Zhongzao 39(Z-39)and Lingliangyou 268(L-268),and two unstable-yielding short-growth duration rice cultivars,Zhongjiazao 17(Z-17)and Zhuliangyou 819(Z-819).The stability of agronomic parameters was represented by the coefficient of variation(CV).The respective CVs of yield in Z-17,Z-819,Z-39,and L-268 were 10.2%,10.1%,4.5%,and 5.7%in 2021 and 19.7%,15.0%,5.4%,and 6.5%in 2022.The respective CVs of grain weight were 6.3%,5.7%,3.4%,and 4.5%in Z-17,Z-819,Z-39,and L-268 in 2021,and 8.1%,6.3%,1.5%,and 0.8%in 2022.The mean source capacity per spikelet and pre-heading non-structural carbohydrate reserves per spikelet(NSC_(pre))were 7%–43%and7%–72%lower in Z-819 and Z-17than in L-268 and Z-39 in 2021 and 2022.The mean quantum yield of photosystem II photochemistry of leaf,leaf area index,and specific leaf weight of L-268 and Z-39 were higher than those of Z-819 and Z-17 at the heading stage.This study suggests that high NSC_(pre),caused by great leaf traits before heading,increases source capacity per spikelet and its stability,thereby increasing the stability of grain weight and yield.Increasing NSC_(pre)is critical for achieving grain weight and yield stability in short-growth duration rice.

DNA cytosine methylation dynamics and functional roles in horticultural crops

Methylation of cytosine is a conserved epigenetic modification that maintains the dynamic balance of methylation in plants under the regulation of methyltransferases and demethylases.In recent years,the study of DNA methylation in regulating the growth and development of plants and animals has become a key area of research.This review describes the regulatory mechanisms of DNA cytosine methylation in plants.It summarizes studies on epigenetic modifications of DNA methylation in fruit ripening,development,senescence,plant height,organ size,and under biotic and abiotic stresses in horticultural crops.The review provides a theoretical basis for understanding the mechanisms of DNA methylation and their relevance to breeding,genetic improvement,research,innovation,and exploitation of new cultivars of horticultural crops.

Natural variation in SlSOS2 promoter hinders salt resistance during tomato domestication

Increasing soil salinization seriously impairs plant growth and development,resulting in crop loss.The Salt-Overly-Sensitive(SOS)pathway is indispensable to the mitigation of Na+toxicity in plants under high salinity.However,whether natural variations of SOS2 contribute to salt tolerance has not been reported.Here a natural variation in the SlSOS2 promoter region was identified to be associated with root Na+/K+ratio and the loss of salt resistance during tomato domestication.This natural variation contains an ABI4-binding cis-element and plays an important role in the repression of SlSOS2 expression.Genetic evidence revealed that SlSOS2 mutations increase root Na+/K+ratio under salt stress conditions and thus attenuate salt resistance in tomato.Together,our findings uncovered a critical but previously unknown natural variation of SOS2 in salt resistance,which provides valuable natural resources for genetic breeding for salt resistance in cultivated tomatoes and other crops.

Reduction in cadmium accumulation in japonica rice grains by CRISPR/Cas9-mediated editing of OsNRAMP5

Cadmium(Cd) intake is harmful to human health and Cd contamination in rice grains represents a severe threat to those consuming rice as a staple food. Knockout of Cd transporters is a promising strategy to reduce Cd accumulation in rice grains. OsNRAMP5 is the major transporter for Cd and manganese(Mn) uptake in rice. Nevertheless, it is uncertain whether knockout of OsNRAMP5 is applicable to produce low Cd rice without affecting plant growth and grain yield. In this study, we adopted CRISPR/Cas9-based gene editing technology to knock out OsNRAMP5 in two japonica varieties. We generated three independent transgene-free osnramp5 mutants and investigated the effect of osnramp5 mutations on Cd accumulation and plant growth. Hydroponic experiments showed that plant growth and chlorophyll content were significantly reduced in osnramp5 mutants at low Mn conditions, and this defective growth in the mutants could be fully rescued by supply of high levels of Mn. Cd and Mn accumulation in both roots and shoots was markedly reduced in the mutants compared to that in wild-type plants. In paddy field experiments, although Cd in flag leaves and grains was greatly reduced in osnramp5 mutants, some agronomic traits including plant height, seed setting rate, and grain number per panicle were affected in the mutants, which ultimately caused a mild reduction in grain yield. The reduced plant growth in the mutants can be attributed to a marked decrease in Mn accumulation. Our results reveal that the manipulation of OsNRAMP5 should be treated with caution: When assessing the applicability of osnramp5 mutants, soil pH and soil water content in paddy fields need to be taken into consideration, since they might affect the levels of available Mn in the soil and consequently determine the effect of the mutation on grain yield.

Plant abiotic stress response and nutrient use efficiency

Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth,productivity and quality.Plants have evolved mechanisms to perceive these environmental challenges,transmit the stress signals within cells as well as between cells and tissues,and make appropriate adjustments in their growth and development in order to survive and reproduce.In recent years,significant progress has been made on many fronts of the stress signaling research,particularly in understanding the downstream signaling events that culminate at the activation of stress-and nutrient limitation-responsive genes,cellular ion homeostasis,and growth adjustment.However,the revelation of the early events of stress signaling,particularly the identification of primary stress sensors,still lags behind.In this review,we summarize recent work on the genetic and molecular mechanisms of plant abiotic stress and nutrient limitation sensing and signaling and discuss new directions for future studies.

Reactive oxygen species signaling and stomatal movement in plant responses to drought stress and pathogen attack

Stomata, the pores formed by a pair of guard cells, are the main gateways for water transpiration and photosynthetic CO_2 exchange, as well as pathogen invasion in land plants. Guard cell movement is regulated by a combination of environmental factors, including water status, light, CO_2 levels and pathogen attack, as well as endogenous signals, such as abscisic acid and apoplastic reactive oxygen species(ROS). Under abiotic and bioticstress conditions, extracellular ROS are mainly produced by plasma membrane-localized NADPH oxidases, whereas intracellular ROS are produced in multiple organelles. These ROS form a sophisticated cellular signaling network, with the accumulation of apoplastic ROS an early hallmark of stomatal movement. Here, we review recent progress in understanding the molecular mechanisms of the ROS signaling network,primarily during drought stress and pathogen attack. We summarize the roles of apoplastic ROS in regulating stomatal movement, ABA and CO_2 signaling, and immunity responses.Finally, we discuss ROS accumulation and communication between organelles and cells. This information provides a conceptual framework for understanding how ROS signaling is integrated with various signaling pathways during plant responses to abiotic and biotic stress stimuli.

Epigenetic regulation in plant abiotic stress responses

In eukaryotic cells,gene expression is greatly influenced by the dynamic chromatin environment.Epigenetic mechanisms,including covalent modifications to DNA and histone tails and the accessibility of chromatin,create various chromatin states for stress-responsive gene expression that is important for adaptation to harsh environmental conditions.Recent studies have revealed that many epigenetic factors participate in abiotic stress responses,and various chromatin modifications are changed when plants are exposed to stressful environments.In this review,we summarize recent progress on the cross-talk between abiotic stress response pathways and epigenetic regulatory pathways in plants.Our review focuses on epigenetic regulation of plant responses to extreme temperatures,drought,salinity,the stress hormone abscisic acid,nutrient limitations and ultraviolet stress,and on epigenetic mechanisms of stress memory.

Genome editing for plant research and crop improvement

The advent of clustered regularly interspaced short palindromic repeat(CRISPR) has had a profound impact on plant biology, and crop improvement. In this review, we summarize the state-of-the-art development of CRISPR technologies and their applications in plants, from the initial introduction of random small indel(insertion or deletion) mutations at target genomic loci to precision editing such as base editing, prime editing and gene targeting. We describe advances in the use of class 2, types II, V, and VI systems for gene disruption as well as for precise sequence alterations, gene transcription, and epigenome control.

Construction of an anchoring SSR marker genetic linkage map and detection of a sex-linked region in two dioecious populations of red bayberry

Red bayberry(Morella rubra)is an evergreen fruit tree found in southern China whose whole-genome sequence has recently been published.We updated the linkage map of the species by adding 118 SSR markers and the femalespecific marker MrFT2_BD-SEX.The integrated map included eight linkage groups and spanned 491 cM.Eleven sexassociated markers were identified,six of which were located in linkage group 8,in agreement with the previously reported location of the sex-determining region.The MrFT2_BD-SEX marker was genotyped in 203 cultivated accessions.Among the females of the accessions,we found two female-specific alleles,designated W-b(151 bp)and W-d(129 bp).We previously found that‘Dongkui’,a female cultivar,could produce viable pollen(we refer to such plants‘Dongkui-male’)and serve as the paternal parent in crosses.The genotypes of the MrFT2_BD-SEX marker were W-b/Z in‘Biqi’and W-d/Z in‘Dongkui-male’.The progeny of a cross between these parents produced a 3:1 female(W-)to male(ZZ)ratio and the expected 1:1:1:1 ratio of W-b/W-d:W-b/Z:W-d/Z:Z/Z.In addition,the flowering and fruiting phenotypes of all the F1 progeny fit their genotypes.Our results confirm the existence of ZW sex determination and show that the female phenotype is controlled by a single dominant locus(W)in a small genomic region(59 kb and less than 3.3 cM).Furthermore,we have produced a homozygous“super female”(WW)that should produce all-female offspring in the F2 generation,providing a foundation for commercial use and presenting great potential for use in modern breeding programs.

Trimming of N-Glycans by the Golgi-Localized α-1,2-Mannosidases, MNS1 and MNS2, Is Crucial for Maintaining RSW2 Protein Abundance during Salt Stress in Arabidopsis

天门冬素(Asn/N ) 连接了 glycans 为蛋白质合拢， trafficking，和 endoplasmic 是重要的在优核质的联系蜂窝胃的降级。glycoproteins 的成熟包含在 Golgi 由另外的糖分子的 mannosidases 和三分支的 N-glycans 的增加整修 mannosyl 残余。然而，调停 Golgi 的甘露糖整修的生物重要性充分没被理解。这里，我们显示出二机能上地冗余的 mannosidases， MNS1 和 MNS2 的那废除，为在 A 和工厂 N-glycans 的 C 分支上整修的 -1,2-mannose 负责在 Arabidopsis 在盐压力条件下面导致严重的根生长抑制。相反，有在 oligosaccharide 先锋的生合成的缺点的异种当甘露糖整修不在时显示了提高的盐忍耐。然而，在 EBS3 的变化，为分叉的 N-glycan 先锋的形成被要求，压制了 mns1 mns2 的盐敏感的显型两倍异种。有趣地，我们观察了那 ? 纤维素生合成在高咸度下面在 mns1 mns2 根被损害。一致地， ? 许多膜抛锚了 endo -- 在纤维素生合成起一个关键作用的 1,4-endoglucanase (RSW2/KOR ) 和它的变异的变体 rsw2-1 ? 被调制由 ? 在盐应力下面整修的 -1,2-mannose。RSW2 的 Overexpression 能部分救 mns1 mns2 的盐敏感的显型。一起拿，这些结果建议 N-glycans 整修的那 MNS1/2-mediated 甘露糖在 modulating glycoprotein 丰富是关键的在植物承受盐应力。

Epigenetic regulation of plant immunity:from chromatin codes to plant disease resistance

Facing a deteriorating natural environment and an increasing serious food crisis,bioengineering-based breeding is increasing in importance.To defend against pathogen infection,plants have evolved multiple defense mechanisms,including pathogen-associated molecular pattern(PAMP)-triggered immunity(PTI)and effector-triggered immunity(ETI).A complex regulatory network acts downstream of these PTI and ETI pathways,including hormone signal transduction and transcriptional reprogramming.In recent years,increasing lines of evidence show that epigenetic factors act,as key regulators involved in the transcriptional reprogramming,to modulate plant immune responses.Here,we summarize current progress on the regulatory mechanism of DNA methylation and histone modifications in plant defense responses.In addition,we also discuss the application of epigenetic mechanism-based resistance strategies in plant disease breeding.

Plant phosphate nutrition:sensing the stress

Phosphorus(P)is obtained by plants as phosphate(Pi)from the soil and low Pi levels affects plant growth and development.Adaptation to low Pi condition entails sensing internal and external Pi levels and translating those signals to molecular and morphophysiological changes in the plant.In this review,we present findings related to local and systemin Pi sensing with focus the molecular mechanisms behind root system architectural changes and the impact of hormones and epigenetic mechanisms affecting those changes.We also present some of the recent advances in the Pi sensing and signaling mechanisms focusing on inositol pyrophosphate InsP8 and its interaction with SPX domain proteins to regulate the activity of the central regulator of the Pi starvation response,PHR.

A novel mitochondrial protein is required for cell wall integrity,auxin accumulation and root elongation in Arabidopsis under salt stress

Maintenance of root elongation is beneficial for the growth and survival of plants under salt stress,but currently the cellular components involved in the regulation of root growth under high salinity are not fully understood.In this study,we identified an Arabidopsis mutant,rres1,which exhibited reduced root elongation under treatment of a variety of salts,including NaCl,NaNO3,KCl,and KNO3.RRES1 encodes a novel mitochondrial protein and its molecular function is still unknown.Under salt stress,the root meristem length was shorter in the rres1 mutant compared to the wild type,which was correlated with a reduced auxin accumulation in the mutant.Reactive oxygen species(ROS),as important signals that regulate root elongation,were accumulated to higher levels in the rres1 mutant than the wild type after salt treatment.Measurement of monosaccharides in the cell wall showed that arabinose and xylose contents were decreased in the rres1 mutant under salt stress,and application of boric acid,which is required for the crosslinking of pectic polysaccharide rhamnogalacturonan-II(RG-II),largely rescued the root growth arrest of the rres1 mutant,suggesting that RRES1 participates in the maintenance of cell wall integrity under salt stress.GUS staining assay indicated that the RRES1 gene was expressed in leaves and weakly in root tip under normal conditions,but its expression was dramatically increased in leaves and roots after salt treatment.Together,our study reveals a novel mitochondrial protein that regulates root elongation under salt stress via the modulation of cell wall integrity,auxin accumulation,and ROS homeostasis.

Fast genetic mapping in barley:case studies of cuticle mutants using RNA-sequencing

Barley(Hordeum vulgare L.)is one of the earliest domesticated crop species and ranked as the fourth largest cereal production worldwide.Forward genetic studies in barley have greatly advanced plant genetics during the last century;however,most genes are identified by the conventional mapping method.Array genotyping and exome-capture sequencing have also been successfully used to target the causal mutation in barley populations,but these techniques are not widely adopted because of associated costs and partly due to the huge genome size of barley.This review summarizes three mapping cases of barley cuticle mutants in our laboratory with the help of RNA-sequencing.The causal mutations have been successfully identified for two of them and the target genes are located in the pericentromeric regions.Detailed information on the mapping-by-sequencing,mapping-and-sequencing,and RNA-sequencing assisted linkage mapping are presented and some limitations and challenges on the mapping assisted by RNA sequencing are also discussed.The alternative and elegant methods presented in this review may greatly accelerate forward genetics of barley mapping,especially for laboratories without large funding.

Publisher Correction:A novel mitochondrial protein is required for cell wall integrity,auxin accumulation and root elongation in Arabidopsis under salt stress

Correction:Stress Biol 2,13(2022)https://doi.org/10.1007/s44154-022-00036-3 Following publication of this article(Yu et al.2022),it is noticed that the section‘Materials and methods’was placed in a wrong place in the main text of this article due to a typesetting error.The original article(Yu et al.2022)was updated.