Enhancer of Shoot Regeneration 2(ESR2)regulates pollen maturation and vitality in watermelon(Citrullus lanatus)

Watermelon(Citrullus lanatus)holds global significance as a fruit with high economic and nutritional value.Exploring the regulatory network of watermelon male reproductive development is crucial for developing male sterile materials and facilitating cross-breeding.Despite its importance,there is a lack of research on the regulation mechanism of male reproductive development in watermelon.In this study,we identified that ClESR2,a VIIIb subclass member in the APETALA2/Ethylene Responsive Factor(AP2/ERF)superfamily,was a key factor in pollen development.RNA insitu hybridization confirmed significantClESR2 expression in the tapetum and pollen during the later stage of anther development.The pollens of transgenic plants showed major defects in morphology and vitality at the late development stage.The RNA-seq and protein interaction assay confirmed that ClESR2 regulates pollen morphology and fertility by interacting with key genes involved in pollen development at both transcriptional and protein levels.These suggest that Enhancer of Shoot Regeneration 2(ESR2)plays an important role in pollen maturation and vitality.This study helps understand the male reproductive development of watermelon,providing a theoretical foundation for developing male sterile materials.

Identification of potential key genes in resveratrol biosynthesis via transcriptional analyses of berry development in grapevine(Vitis spp.)genotypes varying in trans-resveratrol content

Resveratrol is an important secondary metabolite not only owing to its function as a phytoalexin,but also its potential benefits to human health.In this study,the content of trans-resveratrol was documented in seven accessions of grapevine,in the seed,pulp and skin of berries,and at three developmental stages.The highest amount(2.99μg g^(−1) FW)was found in the skin of berries at the ripe stage from V.amurensis‘Tonghua-3'.Resveratrol was not detected in several samples,including skin of berries at the green hard or véraison stage from V.davidii‘Tangwei'.We carried out transcriptional profiling of developing‘Tonghua-3'and‘Tangwei'berries to identify gene expression patterns that may be linked with the difference in resveratrol content between these accessions.The expression levels of several differentially expressed genes(DEGs)with presumed function in resveratrol biosynthesis,including STILBENE SYNTHASEs(STSs),CINNAMATE 4-HYDROXYLASEs(C4Hs)and 4-COUMARATE-COA LIGASEs(4CLs),were significantly higher in‘Tonghua-3',than in'Tangwei'during the véraison and ripe stages.Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses suggested that these DEGs were enriched for multiple biological processes at the three stages of fruit development.Additionally,we identified a total of 36 transcription factors,including MYBs,WRKYs,ERFs,bHLHs and bZIPs,that were coexpressed with 17 STSs via a weighted gene co-expression network analysis,suggesting roles as regulators of resveratrol biosynthesis.Overall,these findings provide insight into genotypic differences in resveratrol biosynthesis in grapevine,as well as the molecular genetics of its regulation.

GGE biplot analysis of yield stability and test location representativeness in proso millet (Panicum miliaceum L.) genotypes

The experiments were conducted for three consecutive years across 14 locations using 9 non-waxy proso millet genotypes and 16 locations using 7 waxy proso millet genotypes in China. The objectives of this study were to analyze yield stability and adaptability of proso millets and to evaluate the discrimination and representativeness of locations by analysis of vari- ance （ANOVA） and genotype and genotype by environment interaction （GGE） biplot methods. Grain yields of proso millet genotypes were significantly influenced by environment （E）, genotype （G） and their interaction （GxE） （P〈0.1%）. GxE inter- action effect was six times higher than G effect in non-waxy group and seven times in waxy group. N04-339 in non-waxy and Neimi 6 （NM6） in waxy showed higher grain yields and stability compared with other genotypes. Also, Neimi 9 （NM9, a non-waxy cultivar） and 90322-2-33 （a waxy cultivar） showed higher adaptability in 7 and in 11 locations, respectively. For non-waxy, Dalat, Inner Mongolia （E2） and Wuzhai, Shanxi （E5） were the best sites among all the locations for maximizing the variance among candidate cultivars, and Yanchi, Ningxia （El0） had the best representativeness. Wuzhai, Shanxi （e9） and Yanchi, Ningxia （e14） were the best representative locations, and Baicheng, Jilin （e2） was better discriminating location than others for waxy genotypes. Based on our results, El0 and e14 have enhanced efficiency and accuracy for non-waxy genotypes and waxy genotypes selection, respectively in national regional test of proso millet varieties.

A point mutation resulting in a 13 bp deletion in the coding sequence of Cldf leads to a GA-deficient dwarf phenotype in watermelon

The dwarf architecture is an important and valuable agronomic trait in watermelon breeding and has the potential to increase fruit yield and reduce labor cost in crop cultivation.However,the molecular basis for dwarfism in watermelon remains largely unknown.In this study,a recessive dwarf allele(designated as Cldf(Citrullus lanatus dwarfism))was fine mapped in a 32.88 kb region on chromosome 09 using F2 segregation populations derived from reciprocal crossing of a normal line M08 and a dwarf line N21.Gene annotation of the corresponding region revealed that the Cla015407 gene encoding a gibberellin 3β-hydroxylase functions as the best possible candidate gene for Cldf.Sequence analysis showed that the fourth polymorphism site(a G to A point mutation)at the 3′AG splice receptor site of the intron leads to a 13 bp deletion in the coding sequence of Cldf in dwarf line N21 and thus results in a truncated protein lacking the conserved domain for binding 2-oxoglutarate.In addition,the dwarf phenotype of Cldf could be rescued by exogenous GA3 application.Phylogenetic analysis suggested that the small multigene family GA3ox(GA3 oxidase)in cucurbit species may originate from three ancient lineages in Cucurbitaceae.All these data support the conclusion that Cldf is a GA-deficient mutant,which together with the cosegregated marker can be used for breeding new dwarf cultivars.

Sugar metabolism and accumulation in the fruit of transgenic apple trees with decreased sorbitol synthesis

Both sorbitol and sucrose are synthesized in source leaves and transported to fruit for supporting fruit growth in tree fruit species of the Rosaceae family.In apple(Malus domestica),antisense suppression of aldose-6-phosphate reductase,the key enzyme for sorbitol synthesis,significantly decreased the sorbitol concentration but increased the sucrose concentration in leaves,leading to a lower sorbitol but a higher sucrose supply to fruit in these plants.In response to this altered carbon supply,the transgenic fruit had lower concentration of sorbitol and much higher concentration of glucose but similar levels of fructose,sucrose,and starch throughout fruit development relative to the untransformed control.Activities of sorbitol dehydrogenase,fructokinase,and sucrose phosphate synthase were lower,whereas activities of neutral invertase,sucrose synthase,and hexokinase were higher in the transgenic fruit during fruit development.Transcript levels of MdSOT1,MdSDHs,MdFK2,and MdSPS3/6 were downregulated,whereas transcript levels of MdSUC1/4,MdSUSY1-3,MdNIV1/3,MdHKs,and MdTMT1 were upregulated in the transgenic fruit.These findings suggest that the Sucrose cycle and the sugar transport system are very effective in maintaining the level of fructose and provide insights into the roles of sorbitol and sucrose in regulating sugar metabolism and accumulation in sorbitol-synthesizing species.

Effects of Exogenous Phthalic and Cinnamic Acids on Enzyme Activities and Microbial Community Structures in Rhizosphere Soil of Adzuki Bean

The aim of this study was to find out the effects of exogenous phenolic acids on soil microbes and enzymes in rhizosphere soil of adzuki bean. In the pot experiment of adzuki bean, phthalic and cinnamic acids were added at four concentrations, 0 （control）, 0.1, 1 and 10 mmol/L, to investigate the changes in the mi- croflora and enzyme activities in rhizosphere soil of adzuki bean as well as relations between them. The results showed that both phthalic and cinnamic acids could inhibit the activities of soil enzymes, including catalase, sucrase, phosphatase and urease. Higher concentrations （10 mmol/L） of phthalic and cinnamic acids showed more significant effects. In addition, the application of phthalic and cinnamic acids reduced the populations of bacteria and actinomycetes and significantly increased the population of fungi. Correlations analysis showed that phosphatase activity had an extremely significant positive correlation with bacterial population, a significant positive correlation with actinomycete population, and a significant negative correlation with fungal population. Phthalic and cinnamic acids could result in imbalanced microbe compositions, reduce enzyme activities and present evident allelopathy in rhizosphere soil.

Grapevine VlbZIP30 improves drought resistance by directly activating VvNAC17 and promoting lignin biosynthesis through the regulation of three peroxidase genes

Drought stress severely affects grapevine quality and yield,and recent reports have revealed that lignin plays an important role in protection from drought stress.Since little is known about lignin-mediated drought resistance in grapevine,we investigated its significance.Herein,we show that VlbZIP30 mediates drought resistance by activating the expression of lignin biosynthetic genes and increasing lignin deposition.Transgenic grapevine plants overexpressing VlbZIP30 exhibited lignin deposition(mainly G and S monomers)in the stem secondary xylem under control conditions,which resulted from the upregulated expression of VvPRX4 and VvPRX72.Overexpression of VlbZIP30 improves drought tolerance,characterized by a reduction in the water loss rate,maintenance of an effective photosynthesis rate,and increased lignin content(mainly G monomer)in leaves under drought conditions.Electrophoretic mobility shift assay,luciferase reporter assays,and chromatin immunoprecipitation-qPCR assays indicated that VlbZIP30 directly binds to the G-box cis-element in the promoters of lignin biosynthetic(VvPRX N1)and drought-responsive(VvNAC17)genes to regulate their expression.In summary,we report a novel VlbZIP30-mediated mechanism linking lignification and drought tolerance in grapevine.The results of this study may be of value for the development of molecular breeding strategies to produce drought-resistant fruit crops.

Boosting proso millet yield by altering canopy light distribution in proso millet/mung bean intercropping systems

To elucidate the mechanism by which intercropping proso millet(Panicum miliaceum L.)with mung bean(Vigna radiata L.)increases proso millet yield and to determine how this higher yield results from maximization of resources use efficiency,we designed and conducted four strip intercropping row arrangements,including two rows of proso millet alternating with two rows of mung bean(2P2M),four rows of proso millet alternating with two rows of mung bean(4P2M),four rows of proso millet alternating with four rows of mung bean(4P4M),two rows of proso millet alternating with four rows of mung bean(2P4M),sole proso millet(SP,control)and sole mung bean(SM,control)in Yulin,Shaanxi,China.Photosynthetically active radiation(PAR)in the canopy,radiation use efficiency(RUE),leaf photosynthetic characteristics,dry matter accumulation and allocation,and yield of proso millet were investigated.The results showed that the intercropping systems had higher PAR than the monoculture.Mean PAR intensities were increased by respectively 2.2%–23.4%,19.8%–59.7%,and 61.2%–133.3%in the proso millet upper,middle and lower canopies compared with SP.The increase in PAR directly increased RUE,a result attributed mainly to the increase in photosynthetic capacity,including net photosynthetic rate and chlorophyll content.These responses resulted in increased dry matter allocation to plant organs.Yield of intercropped proso millet was 6.8%–37.3%higher than that under monoculture and the land equivalent ratios for the different intercropping patterns were all greater than unity(>1).In general,yield followed a positive linear function of PAR in the intercropping system.The results indicated that intercropping can boost proso millet yield,evidently by altering light distribution within its canopy and consequently increasing RUE,thereby increasing leaf photosynthetic capacity,dry matter accumulation,and allocation to the grain.The optimum combination for improving the growth and yield of proso millet on the Loess Plateau of China was 2P4M.

Insecticide resistance of the field populations of oriental armyworm,Mythimna separata(Walker) in Shaanxi and Shanxi provinces of China

Resistance of five field populations of Mythimna separata（Walker） collected from Shaanxi and Shanxi provinces of China to six different insecticides was evaluated by leaf dip method in the laboratory. The results showed that all populations were relatively sensitive to emamectin benzoate with a resistance ratio（RR） of 0.583–1.583 folds. All populations showed susceptible or low level resistance to chlorantraniliprole and beta-cypermethrin. Compared with a relatively susceptible strain of M. separata, the resistance level of the whole populations ranged from susceptible to moderate to chlorpyrifos and lambda-cyhalothrin, moderate to high to phoxim（RR=19.367–70.100） except for population from Sanyuan County（RR=2.567）. Pair-wise correlation analysis among different insecticides indicated that chlorpyrifos has a significantly positive and significant correlation with emamectin benzoate. Chlorantraniliprole didn＇t have significant correlation with emamectin benzoate, chlorpyrifos and phoxim. Therefore, emamectin benzoate, chlorantraniliprole and beta-cypermethrin are recommended to control oriental armyworm. Meanwhile, to postpone the occurrence and development of insecticide resistance in Shaanxi and Shanxi provinces, alternative and rotational application of insecticides between chlorantraniliprole and emamectin benzoate or chlorpyrifos is necessary.

Effects of constant and stage-specific-alternating temperature on the survival, development and reproduction of the oriental armyworm, Mythimna separata(Walker)(Lepidoptera: Noctuidae)

Migratory insects make diverse adaptive strategies in response to changes in external environment. Temperature has an impact on the survival, development, reproduction, and migration initiation of insects. Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention. Three constant temperature treatments（20, 25 and 30℃） and three pupal-alternating temperature treatments（20–25, 25–20 and 25–30℃） were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops. The 25℃ treatment was considered optimal with 20 and 30℃ as low suitable temperature and high temperatures, respectively. The survival rate was relatively low before third instar larvae at 20℃（63.0%） and 20–25℃（70.1%）, and extreme low after pupal stage at 30℃（20.6%）. Developmental duration of each stage was negatively correlated with temperature. The adult preoviposition period, when most migratory insects initiate migration, was the shortest at 25℃（2.69d） but was lengthened at both low suitable（7.48d for 20℃, 6.91d for 25–20℃ and 4.57d for 20–25℃） and high temperatures（3.74d for 25–30℃ and 5.00d for 30℃）. Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature. The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.

Advancements in plant regeneration and genetic transformation of grapevine(Vitis spp.)

Grapevine(Vitis spp.)is one of the most economically important fruit crops worldwide,and there is considerable interest in improving its major agronomic and enological traits in response to ever-changing agricultural environments and consumer demands.Molecular genetic techniques in particular,associated with rapid technological advancements,provide an attractive alternative to conventional breeding approaches for developing new grapevine varieties with enhanced yield performance,quality,stress tolerance and disease resistance.To date,several grapevine varieties have been transformed with genes associated with diverse functions through biolistic bombardment and/or Agrobacterium-mediated transformation,and transgenic grape lines have been obtained using established regeneration systems.Nevertheless,a wide range of factors,including genotype,explant source and culture medium,have been shown to affect the efficiency of plant regeneration.Moreover,the selection and use of acceptor materials,bacterial strain and cell density,selectable markers and selection methods also influence transformation efficiency.This paper provides an overview of recent advances in grapevine regeneration and genetic transformation and in-depth discussion of the major limiting factors,and discusses promising future strategies to develop robust plant regeneration and genetic transformation in grapevine.

Transcriptome of Erysiphe necator-infected Vitispseudoreticulata leaves provides insight into grapevineresistance to powdery mildew

Powdery mildew(PM),which is caused by the pathogen Erysiphe necator(Schw.)Burr.,is the single most damaging disease of cultivated grapes(Vitis vinifera)worldwide.However,little is known about the transcriptional response of grapes to infection with PM.RNA-seq analysis was used for deep sequencing of the leaf transcriptome to study PM resistance in Chinese wild grapes(V.pseudoreticulata Baihe 35-1)to better understand the interaction between host and pathogen.Greater than 100 million(M)90-nt cDNA reads were sequenced from a cDNA library derived from PM-infected leaves.Among the sequences obtained,6541 genes were differentially expressed(DEG)and were annotated with Gene Ontology terms and by pathway enrichment.The significant categories that were identified included the following:defense,salicylic acid(SA)and jasmonic acid(JA)responses;systemic acquired resistance(SAR);hypersensitive response;plant–pathogen interaction;flavonoid biosynthesis;and plant hormone signal transduction.Various putative secretory proteins were identified,indicating potential defense responses to PMinfection.In all,318 putative R-genes and 183 putative secreted proteins were identified,including the defense-related R-genes BAK1,MRH1 and MLO3 and the defense-related secreted proteins GLP and PR5.The expression patterns of 16 genes were further illuminated by RT-qPCR.The present study identified several candidate genes and pathways that may contribute to PM resistance in grapes and illustrated that RNA-seq is a powerful tool for studying gene expression.The RT-qPCR results reveal that effective resistance responses of grapes to PM include enhancement of JA and SAR responses and accumulation of phytoalexins.

Whole-genome sequencing reveals rare off-target mutations in CRISPR/Cas9-edited grapevine

The CRISPR(clustered regularly interspaced short palindromic repeats)-associated protein 9(Cas9)system is a powerful tool for targeted genome editing,with applications that include plant biotechnology and functional genomics research.However,the specificity of Cas9 targeting is poorly investigated in many plant species,including fruit trees.To assess the off-target mutation rate in grapevine(Vitis vinifera),we performed whole-genome sequencing(WGS)of seven Cas9-edited grapevine plants in which one of two genes was targeted by CRISPR/Cas9 and three wild-type(WT)plants.In total,we identified between 202,008 and 272,397 single nucleotide polymorphisms(SNPs)and between 26,391 and 55,414 insertions/deletions(indels)in the seven Cas9-edited grapevine plants compared with the three WT plants.Subsequently,3272 potential off-target sites were selected for further analysis.Only one off-target indel mutation was identified from the WGS data and validated by Sanger sequencing.In addition,we found 243 newly generated off-target sites caused by genetic variants between the Thompson Seedless cultivar and the grape reference genome(PN40024)but no true off-target mutations.In conclusion,we observed high specificity of CRISPR/Cas9 for genome editing of grapevine.

Mapping of Quantitative Trait Loci for Adult Plant Resistance to Stripe Rust in German Wheat Cultivar Ibis

The German wheat cultivar Ibis has excellent adult plant resistance（APR） to stripe rust in Gansu,a hotspot for stripe rust in China.To elucidate the genetic basis of APR to stripe rust in Ibis,237 F3 lines derived from the cross Ibis/Huixianhong were evaluated at Tianshui,Gansu,in the 2008-2009 and 2009-2010 cropping seasons,and at Chengdu,Sichuan Province,China,in the 2009-2010 cropping season.Inoculations were conducted with a mixture of several prevalent Pst races in both locations.Maximum disease severity（MDS） data showed a continuous distribution of response,indicating quantitative nature of resistance to stripe rust in Ibis.The broad-sense heritability of MDS was 0.75 based on the mean values averaged across three environments.A total of 723 simple sequence repeat（SSR） markers were used to map the QTL for APR by inclusive composite interval mapping（ICIM）.QTLs mapping to chromosomes 2BS and 6BS,designated as QYr.caas-2BS.1 and QYr.caas-6BS.1,respectively,explained 4.1-40.7% of the phenotypic variance in MDS across environments.The major effect QTL QYr.caas-2BS.1,flanked by Xgwm148 and Xwmc360,was consistently detected at all three sites as well as the averaged data over three environments,accounting for 40.7,24.2,5.2 and 29.9% of phenotypic variance,respectively.The molecular markers closely linked to this QTL have potential for use in marker-assisted selection and gene pyramiding to improve the durability of stripe rust resistance in wheat breeding.

Association of host plant growth and weed occurrence with armyworm(Mythimna separata) damage in corn fields

To clarify association between armyworm（Mythimna separata） damage level and the corn growth and weed occurrence, we investigated corn plant height, stem diameter and vigor as well as weed coverage and biomass. The investigations were conducted at three locations of Shaanxi Province, China which were suffered seriously from armyworm. Significant correlations were found between the parameters analyzed. At stunted corn growth and presence of plenty of weeds, the armyworm damage tended to be heavy; oppositely, when corn grew well and weed density were low, armyworm harm was the minimal. Therefore, corn growing status and weed density can significantly affect armyworm damage level. Our results imply that promoting corn growth and timely removal of weeds are conducive to reducing armyworm occurrence.

VlbZIP30 of grapevine functions in dehydration tolerance via the abscisic acid core signaling pathway

Drought stress limits the growth and development of grapevines,thereby reducing productivity,but the mechanisms by which grapevines respond to drought stress remain largely uncharacterized.Here,we characterized a group A bZIP gene from“Kyoho”grapevine,VlbZIP30,which was shown to be induced by abscisic acid(ABA)and dehydration stress.Overexpression of VlbZIP30 in transgenic Arabidopsis thaliana enhanced dehydration tolerance.Transcriptome analysis revealed that a major proportion of ABA-responsive and/or drought-responsive genes are transcriptionally regulated by VlbZIP30 during ABA or mannitol treatment at the cotyledon greening stage.We identified an A.thaliana G-box motif(CACGTG)and a potential grapevine G-box motif(MCACGTGK)in the promoters of the 39 selected A.thaliana genes upregulated in the transgenic plants and in the 35 grapevine homologs,respectively.Subsequently,using two grapevine-related databases,we found that 74%(23/31)and 84%(21/25)of the detected grapevine genes were significantly upregulated by ABA and drought stress,respectively,suggesting that these genes are involved in ABA or dehydration stress and may be regulated by VlbZIP30 in grapevine.We propose that VlbZIP30 functions as a positive regulator of dehydration-responsive signaling in the ABA core signaling pathway.

Alternatively spliced BobCAL transcripts alter curd morphotypes in a collection of Chinese cauliflower accessions

The curd of cauliflower(Brassica oleracea L.var.botrytis)is a modified inflorescence that is consumed as a vegetable.Curd formation is proposed to be due to a mutation in the BobCAULIFLOWER(BobCAL)gene,but the genetic relationship between BobCAL variation and curd morphotypes remains obscure.To address this question,we collected and classified a collection of 78 cauliflower accessions into four subpopulations according to curd surface features:smooth,coarse,granular,and hairy curd morphotypes.Through the cDNA sequencing of BobCAL alleles,we showed that smooth and coarse accessions characterized by inflorescence meristem arrest presented a strong association with the 451T SNP(BobCAL_T),whereas granular and hairy accessions marked with floral organ arrest presented an association with 451G(BobCAL_G).Interestingly,all BobCAL alleles were alternatively spliced,resulting in a total of four alternative splice(AS)variants due to the retention of the fourth and/or seventh introns.Among accessions with BobCAL_G alleles,the total expression of all these AS variants in granular plants was almost equal to that in hairy plants;however,the expression of the individual AS variants encoding intact proteins relative to those encoding truncated proteins differed.Hairy accessions showed relatively high expression of the individual variants encoding intact proteins,whereas granular accessions displayed relatively low expression.In smooth cauliflower,the overexpression of the BobCAL_Ga variant caused an alteration in the curd morphotype from smooth to hairy,concurrent with an increase in the expression levels of downstream floral identity genes.These results reveal that alternative splicing of BobCAL transcripts is involved in the determination of cauliflower curd morphotypes.

QTL-seq analysis of the seed size trait in grape provides new molecular insights on seedlessness

Seedlessness in grape(Vitis vinifera)is an important commercial trait for both the fresh and drying markets.However,despite numerous studies,the mechanisms and key genes regulating grape seedlessness are mostly unknown.In this study,we sequenced the genomes of the V.vinifera seeded cultivar‘Red Globe’,the seedless cultivar‘Centennial Seedless’,and the derived hybrids.Nonsynonymous single nucleotide polymorphisms(SNPs)were identified by genome sequencing and analyzed using published transcriptome data.Nonsynonymous SNPs occurred in genes related to seed development,which were identified as protein kinases,transcription factors,and cytochrome P450 s and showed differential expression during ovule development in both seeded and seedless grapes.These nonsynonymous SNP-associated genes were mainly involved in biological processes such as hormone balance,seed coat and endosperm development,reproductive organ development,oxidation and reduction,senescence and cell death.A potential quantitative trait locus(QTL)region associated with seed size was characterized based on the SNP-index,and expression analysis of candidate genes in the QTL region during ovule development in multiple seeded and seedless grape cultivars were conducted.Three SNPs were further subjected to SNa Pshot analysis and one SNP in G8 showed 67.5%efficiency in the grape progeny validation.Overall,the data obtained in this study shed light on the differences in seed development between seeded and seedless progeny at the genomic level,which provides valuable resources for future functional studies and grape breeding.

Characterization of wavy root 1,an agravitropism allele,reveals the functions of OsPIN2 in fine regulation of auxin transport and distribution and in ABA biosynthesis and response in rice(Oryza sativa L.)

Root system architecture is influenced by gravity.How the root senses gravity and directs its orientation,so-called gravitropism,is not only a fundamental question in plant biology but also theoretically important for genetic improvement of crop root architecture.However,the mechanism has not been elucidated in most crops.We characterized a rice agravitropism allele,wavy root 1(war1),a loss-of-function allele in OsPIN2,which encodes an auxin efflux transporter.With loss of OsPIN2 function,war1 leads to altered root system architecture including wavy root,larger root distribution angle,and shallower root system due to the loss of gravitropic perception in root tips.In the war1 mutant,polar auxin transport was disrupted in the root tip,leading to abnormal auxin levels and disturbed auxin transport and distribution in columella cells.Amyloplast sedimentation,an important process in gravitropic sensing,was also decreased in root tip columella cells.The results indicated that OsPIN2 controls gravitropism by finely regulating auxin transport,distribution and levels,and amyloplast sedimentation in root tips.We identified a novel role of OsPIN2 in regulating ABA biosynthesis and response pathways.Loss of OsPIN2 function in the war1 resulted in increased sensitivity to ABA in seed germination,increased ABA level,changes in ABA-associated genes in roots,and decreased drought tolerance in the seedlings.These results suggest that the auxin transporter OsPIN2 not only modulates auxin transport to control root gravitropism,but also functions in ABA signaling to affect seed germination and root development,probably by mediating crosstalk between auxin and ABA pathways.

Ectopic expression of VvFUS3,B3-domain transcription factor,in tomato influences seed development via affecting endoreduplication and hormones

FUSCA3(FUS3)is a member of B3-domain transcription factor family and master regulator of seed development.It has potential roles in hormone biosynthesis and signaling pathways and therefore plays diverse roles in plant life cycle,especially in seed germination,dormancy,embryo formation,seed and fruit development,and maturation.However,there is limited information about its functions in seed and fruit development of grapevine.In this study,we expressed VvFUS3 in tomato for its functional characterization.Overexpression of VvFUS3 in tomato led to a reduction in seed number and seed weight without affecting the fruit size.Histological analysis found that both cell expansion and cell division in transgenic seed and fruit pericarp have been affected.However,there were no obvious differences in pollen size,shape,and viability,suggesting that VvFUS3 affects seed development but not the pollen grains.Moreover,the expression of several genes with presumed roles in seed development and hormone signaling pathways was also influenced by VvFUS3.These results suggest that VvFUS3 is involved in hormonal signaling pathways that regulate seed number and size.In conclusion,our study provides novel preliminary information about the pivotal roles of VvFUS3 in seed and fruit development and these findings can potentially serve as a reference for molecular breeding of seedless grapes.