Disruption of Energy Metabolism and Reactive Oxygen Species Homeostasis in Honglian Type-Cytoplasmic Male Sterility(HL-CMS)Rice Pollen

Honglian type-cytoplasmic male sterility(HL-CMS)is caused by the inter-communication between the nucleus and mitochondria.However,the mechanisms by which sterility genes regulate metabolic alterations and changes in mitochondrial morphology in the pollen of HL-CMS remain unclear.In this study,we compared the morphological differences between the pollen of the male sterile line YA and the near-isogenic line NIL-Rf6 using hematoxylin-eosin staining and 4ʹ,6-diamidino-2-phenylindole(DAPI)staining.HL-CMS is characterized by gametophytic sterility,where the aborted pollen grains are empty,and the tapetal layer remains intact.Transmission electron microscopy was employed to observe mitochondrial morphological changes at the microspore stage,revealing significant mitochondrial alterations,characterized by the formation of'large spherical mitochondria',occurred at the binucleate stage in the YA line.Additionally,metabolomics analysis revealed decreased levels of metabolites associated with the carbohydrate and flavonoid pathways.Notably,the decrease in flavonoids was found to contribute to an elevation in reactive oxygen species(ROS)levels.Therefore,we propose a model in which rice fertility is modulated by the levels of pollen carbohydrates and flavonoid metabolites,with impaired mitochondrial energy production and reduced flavonoid biosynthesis as the main causes of ROS accumulation and pollen abortion in rice.

Sterile supernatant of Bacillus subtilis TLD4 controls apple replant disease:Microbial community structure-mediated inhibition of Fusarium

Apple replant disease(ARD)is a common soil-borne disease,and has a negative impact on the growth and yield of apple trees(Jiang et al.,2023).Due to the prevalence of pathogenic Fusarium spp.,the resulting microbial community shift in the rhizosphere soil has been the primary cause of ARD in major apple-producing regions along the Bohai Gulf(Wang et al.,2018).Chemical fumigation is gradually eliminated because of its environmental pollution.Therefore,it is crucial to find sustainable,eco-friendly,and effective biological measures to alleviate ARD(Wang et al.,2022).Since the discovery of antagonistic and plant growthpromoting bacteria(such as Bacillus spp.),their solid microbial fertilizers have been demonstrated to have effective biocontrol properties(Shahid et al.,2021).In view of the variety of natural antifungal compounds of Bacillus spp.(Jasim et al.,2016;Ismaila et al.,2023),there were few reports on applying sterile supernatant of Bacillus spp.to prevent ARD.

The Relation between Anther's Nutrient Metabolism and Pollen Abortion of Male Sterile Lines in Lycium barbarum L.

[ Objective] This study deals with the relation between anther nutrient metabolism and pollen abortion of male sterile lines in Lycium barbarum L., and provides some theoretical references for the pollen abortion mechanism of male sterile lines in Lyciurn barbarurn L.. [Method] By using semi-thin section and cytochemistry technology, the accumulation and distribution of anther nutrient of male sterile and fertile lines in Lycium barbarum L. were observed and compared. [ Result] The result showed that after meiosis, starch grains in the connective parenchyma of anther decreased sharply, and starch grains in epidermis and endothecium were also greatly decreased, while nearly no lipid accumulated in tapetal cells in male sterile lines compared with the fertile lines. The tapetal cells and tetraspore had vacuoles appear successively, and then entered the degenerate process. During the degeneration stage of tapetal cells and tetraspore, starch grains in epidermis and endothecium were still in a smell number and in the connective parenchyme as well. [ Conclusion] The decrease of polysaccharide supplying in anther vascular leads to the disorder of mechanism of glycelipid transforming in tapetal ceils, which triggers the tapetal cells degenerating ahead of time, and the latter gives rise to callus wall failing to degenerate in time. Therefore, the tetrads disintegrate and disappear ultimately due to lack of nutrition.

A putative bHLH transcription factor is a candidate gene for male sterile 32,a locus affecting pollen and tapetum development in tomato

The tomato(Solanum lycopersicum)male sterile 32(ms32)mutant has been used in hybrid seed breeding programs largely because it produces no pollen and has exserted stigmas.In this study,histological examination of anthers revealed dysfunctional pollen and tapetum development in the ms32 mutant.The ms32 locus was fine mapped to a 28.5 kb interval that encoded four putative genes.Solyc01g081100,a homolog of Arabidopsis bHLH10/89/90 and rice EAT1,was proposed to be the candidate gene of MS32 because it contained a single nucleotide polymorphism(SNP)that led to the formation of a premature stop codon.A codominant derived cleaved amplified polymorphic sequence(dCAPS)marker,MS32D,was developed based on the SNP.Real-time quantitative reverse-transcription PCR showed that most of the genes,which were proposed to be involved in pollen and tapetum development in tomato,were downregulated in the ms32 mutant.These findings may aid in marker-assisted selection of ms32 in hybrid breeding programs and facilitate studies on the regulatory mechanisms of pollen and tapetum development in tomato.

Cytomorphology and Cytochemical Localization of K-type and T-type Cytoplasmic Male Sterile Pollens in Wheat

By using the technology of microscopy, electron microscopy and enzyme cytochemical localization , comparison was made of the cytomorphology, ATPase and cytochrome oxidase activity in pollens during microspore formation and pollen development, for K-type cytoplasmic male sterile(CMS)lines,T-type CMS lines and their maintainer lines on wheat. The results indicated that pollen abortion of the T-type CMS lines mainly occurred at the later mononucleate pollen stage, and cytomorphological changes of the abortive pollen began with a vacuolar membrane, and pollen aborting was related to a lack of ATPase activity in the nucleus and nucleolus during the mononucleate pollen stage. Pollen abortion of the K-type CMS lines took place mainly during the later binucleate and trinucleate stages, and cytomorphological changes of the abortion first began with mitochondria. The abortion was related to intine disruption.

Study on the Pollen Thermo-Sensitive and Stigma Exsertion Male Sterile Line Tomato (Lycopersicon esculentum Mill.) cv. Da107

To accelerate the breeding process, male sterile line is used to leave out the troublesome procedures of the artificial emasculation in tomato breeding. However, the fertility of the pollen thermo-sensitivity male sterile line (PTMSL) and the stigma exsertion male sterile line (SEMSL) are affected easily by the environments when used alone. The trial materials were Da107 and the control was First. This study was conducted to create a new male sterile line of tomato characterized by pollen thermo-sensitivity and long style by genic recombination through the hybridizing of the PTMSL and SEMSL. Research on the statistics of the pollen germination rate, the contamination rate in F1 and the flower organics indicated that Da107 was an ideal TS and SE male sterile line with the sterility of 95%, as well as it also could be used as fertile line at low temperature. Meanwhile, the results showed that hybrid-seed contamination risk with selfed seeds from residual fertility in Da107 was low.

GAMYB transcription factor LoMYB65 from lily plays a vital role in pollen development

Lily(Lilium spp.)is an important horticultural crop,but its use is limited due to serious pollen contamination problems.There are many studies on pollen development in model plants,but few on flower crops such as lilies.Gibberellin(GA)is a large class of hormones and plays an important role in plant vegetative growth and reproductive development.GAMYB is a group of the R2R3-MYB family upregulated by gibberellin,and plays an important role in anther development.Here,we isolated a novel GAMYB,named LoMYB65,from lily,which was closely related to the AtMYB65 and AtMYB33 in Arabidopsis.Fluorescence quantitative PCR results showed that LoMYB65 was mainly expressed in lily anthers.LoMYB65 could be activated by 288μmol·L^(-1)GA3treatment and the LoMYB65 protein was located in the nucleus and cytoplasm,and had transactivation in yeast and tobacco leaf cells.The conserved motif within 226 amino acids of the C-terminal of LoMYB65 contributed to its transactivation.Overexpression of LoMYB65 caused dwarf phenotype,unnormal tapetum development,less seeds of siliques in transgenic Arabidopsis plants,the transgenic plants showed partly male sterile.Simultaneously,silencing of LoMYB65 with VIGS(Virus Induced Gene Silencing)in lily anthers caused unnormal pollen development and reduced the pollen amount.Overexpression of LoMYB65 in Arabidopsis and silencing of LoMYB65 in lily resulted in decreased pollen counts,so we speculate that LoMYB65 may be dose-dependent.Overall,these findings suggest that LoMYB65 may play an important role in anther development and pollen formation in lily.LoMYB65 may provide a useful candidate gene for pollenless breeding of lily.

Effect of different drying methods on the amino acids,α-dicarbonyls and volatile compounds of rape bee pollen

The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed vacuum drying(PVD),freeze drying(FD),infrared drying(IRD),hot-air drying(HAD)and sun drying(SD)on free amino acids(FAAs),α-dicarbonyl compounds(α-DCs)and volatile compounds(VOCs)in rape bee pollen(RBP)were determined.The results showed that FD significantly released the essential amino acids(EAAs)compared with fresh samples while SD caused the highest loss.Glucosone was the dominantα-DCs in RBP and the highest loss was observed after PVD.Aldehydes were the dominant volatiles of RBP and SD samples contained more new volatile substances(especially aldehydes)than the other four drying methods.Comprehensively,FD and PVD would be potential methods to effectively reduce the quality deterioration of RBP in the drying process.

Effect of wall-disruption on nutrient composition and in vitro digestion of camellia and lotus bee pollens

The nutrient digestion,absorption and biological activity of bee pollen may be limited due to the complex pollen wall.Here,the effect of superfine grinding technology on the release of nutrients from bee pollen were investigated,and their antioxidant activities and in vitro digestion were explored in this study.Results showed that the content of nutrients in bee pollen increased after wall disruption.Among them,fat content increased by 22.55%-8.31%,protein content increased by 0.54%-4.91%,starch content increased by 36.31%-48.64%,soluble sugar content increased by 20.57%-29.67%,total phenolic acid content increased by 11.73%-86.98%and total flavonoids content increased by 14.29%-24.79%.At the same time,the antioxidant activity increased by 14.84%-46.00%.Furthermore,the active components such as phenolic compounds in the wall-disruption bee pollen were more readily to be released during the in vitro digestion,and easier to be absorbed because of their higher bioaccessibility.Antioxidant activities during in vitro digestion were also improved in walldisruption bee pollen.These findings provide evidence that bee pollen wall disruption was suggested,thus,it is more conducive to exerting the value of bee pollen in functional foods.

Morphological and cytological assessments reveal pollen degradation causes pollen abortion in cotton cytoplasmic male sterility lines

Background Understanding the mechanism of male sterility is crucial for producing hybrid seeds and developing sterile germplasm resources.However,only a few cytoplasmic male sterility(CMS)lines of cotton have been produced due to several challenges,like inadequate variation of agronomic traits,incomplete sterility,weak resilience of restorer lines,and difficulty in combining strong dominance.Therefore,the morphological and cytological identification of CMS in cotton will facilitate hybrid breeding.Results Two F_(2) segregating populations of cotton were constructed from cytoplasmic male sterile lines(HaA and 01A,maternal)and restorer lines(HaR and 26R,paternal).Genetic analysis of these populations revealed a segregation ratio of 3:1 for fertile to sterile plants.Phenotypic analysis indicated no significant differences in traits of flower bud development between sterile and fertile plants.However,sterile plants exhibited smaller floral organs,shortened filament lengths,and anther atrophy on the flowering day in comparison with the fertile plants.When performed scanning electron microscopy(SEM),the two F_(2) populations revealed morphological variations in the anther epidermis.Cellular analysis showed no significant differences in pollen development before pollen maturation.Interestingly,between the pollen maturation and flowering stages,the tapetum layer of sterile plants degenerated prematurely,resulting in abnormal pollen grains and gradual pollen degradation.Conclusion The results of this study suggest that fertility-restoring genes are controlled by a single dominant gene.Sterile plants exhibit distinctive floral morphology,which is characterized by stamen atrophy and abnormal anthers.Pollen abortion occurs between pollen maturity and flowering,indicating that premature tapetum degradation may be the primary cause of pollen abortion.Overall,our study provides a theoretical basis for utilizing CMS in hybrid breeding and in-depth investigation of the dominant configuration of cotton hybrid combinations,mechanisms of sterility,and the role of sterile and restorer genes.

DIA-based proteome profiling with PRM verification reveals the involvement of ER-associated protein processing in pollen abortion in Ogura CMS cabbage

Ogura cytoplasmic male sterility(Ogura CMS)is extensively applied in hybrid seed production in cruciferous crops.However,the posttranscriptional molecular basis of Ogura CMS in cruciferous crops remains elusive.Here,a data-independent acquisition-based proteomic approach coupled with a parallel reaction monitoring-based targeted proteomic assay was used to analyze the proteome dynamics of Ogura CMS cabbage line RM and its maintainer line RF during floral bud development to obtain insights into the mechanism underlying Ogura CMS in cruciferous crops.A total of 9162 proteins corresponding to 61464 peptides were identified in RM and RF floral buds.The proteomic fluctuation of RM was weaker than that of RF.Differences in protein expression between RM and RF gradually enlarged with floral bud development.Fifteen continually up-regulated and eight continually down-regulated proteins were found in RM relative to RF throughout floral bud development.Differentially expressed proteins between RM and RF during floral bud development were implicated in the endoplasmic reticulum(ER)-associated protein processing pathway,in which most of them exhibited down-regulated expression in RM.These data suggest that ER-associated protein processing may be involved in pollen abortion in Ogura CMS cabbage by inhibiting the expression of critical factors.Our findings not only deepen the understanding of the molecular mechanisms of Ogura CMS in cruciferous crops but also provide better guidance for applying Ogura CMS in the hybrid breeding of cruciferous crops.

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.

Human impact gradients via anthropogenic pollen indicators:insights gleaned from a case study in the Rif Mountains(Northern Morocco)

Understanding the relationship between modern pollen and vegetation is crucial for interpreting fossil pollen records and assessing human impact on the environment,both of which are essential for effective environmental management strategies.Despite numerous studies on fossil pollen records in the Rif landscape,research specifically focusing on modern pollen and its implications for understanding human impact on the natural landscape is notably lacking.This paper presents novel anthropogenic pollen indicators for the Rif Mountains and seeks to evaluate the gradients of human impact on the southern Mediterranean landscape.We employed a combination of modern pollen analysis,vegetation survey,and ordination techniques,incorporating various environmental and land-use variables.Canonical correspondence analysis(CCA)allowed us to evaluate the relationships between pollen types and environmental variables,helping us identify key anthropogenic pollen indicators associated with land use and human activities:Poaceae,Cannabist,Olea-t,and Asteraceae for cultivation;Brassicaceae,Genista-t,Poaceae,Asteraceae and Plantago-t,for grazing;Apiaceae,Urtica-t and Genista-t for slashing and burning.Additionally,an anthropogenic index score(AIS)was calculated for each sampled location.Correspondence analysis(CA)was then used to correlate each specific pollen type with levels of human impact as follows(a)low(e.g.,Cedrus atlantica-t,Quercus canariensis-t),(b)moderate(e.g.,Erica-t,Arbutus unedo-t,Eucalyptus-t),and(c)high(e.g.,Cannabis-t,Brassicaceae,Olea-t,Nicotiana-t).This paper enhances our comprehension of land-use dynamics and impact levels,providing essential insights for evaluating anthropogenic impact trends and human-induced changes in the Rif Mountains landscape.

High temperature treatment induced production of unreduced 2n pollen in Camellia oleifera

Unreduced gametes through chromosome doubling play a major role in the process of plant polyploidization.Our previous work confirmed that Camellia oleifera can produce natural 2n pollen,and it is possible to induce the 2n pollen formation by high temperature treatment.This study focused on the optimization of the 2n pollen induction technique and the mechanisms of high temperature-induced2n pollen formation in C.oleifera.We found that the optimal protocol for inducing 2n pollen via high temperature was to perform 45℃with4 h at the prophaseⅠstage of the pollen mother cells(PMCs).Meanwhile,high temperature significantly decreased the yield and fertility of2n pollen.Through the observation of meiosis,abnormal chromosome and cytological behaviour was discovered under high-temperature treatment,and we confirmed that the formation of 2n pollen is caused by abnormal cell plate.Based on weighted gene co-expression network analysis,fifteen hub genes related to cell cycle control were identified.After male flower buds were exposed to heat shock,polygalacturonase gene(CoPGX3)was significantly upregulated.We inferred that high temperature causes the CoPGX3 gene to be overexpressed and that CoPGX3 is redistributed into the cytosol where it degrades cytoplasmic pectin,which leads to an abnormal cell plate.Furthermore,abnormal cytokinesis resulted in the formation of dyads and triads,and PMCs divided to produce 2n pollen.Our findings provide new insights into the mechanism of 2n pollen induced by high temperature in a woody plant and lay a foundation for further ploidy breeding of C.oleifera.

Modern pollen-vegetation relationships along altitudinal vegetation belts in the Leigong Mountain of southwestern China

Understanding the distribution,dispersal,and correlation of modern pollen with vegetation in mountainous regions is essential for establishing accurate modern analogs for fossil pollen records.This study,conducted in Leigong Mountain on the YunnanGuizhou Plateau of southwestern China,involved the collection of 35 surface soil samples from diverse vegetation communities along an elevational gradient ranging from 1210 to 1875 meters.The results reveal a close correspondence between modern pollen assemblages and vegetation zones.Principal Component Analysis(PCA)results indicate that pollen assemblages can effectively distinguish between subtropical montane evergreen broad-leaved forest(SEBF)and subtropical montane deciduous broadleaved forest(SDBF).However,both SEBF and SDBF show significant overlap with subtropical montane evergreen-deciduous broad-leaved mixed forest(SEMF).Detrended Correspondence Analysis(DCA)results clearly distinguish the three vegetation zones,and the first axis of DCA shows a significant positive correlation with elevation(p<0.01,R=0.48).Discriminant Analysis(DA)successfully assigns 94.4%of the modern pollen samples to their respective vegetation zones.Pollen taxa such as Impatiens,Astertype,and Rosaceae exhibit significant indicative capabilities for the SEBF zone,effectively distinguishing this vegetation zone from others.Pinus and Alnus display overrepresentation in the Leigong Mountain region,while Quercus(D,deciduous-type)and Poaceae exhibit high representation in the SEBF zone.In the SEBF zone,both pollen diversity and richness are the lowest.Our study reveals the complex relationship between the richness and diversity of pollen and vegetation.The diversity and richness of tree and shrub pollen are found to be lower than those of the corresponding plants.The pollen-vegetation relationship elucidated in this study serves as a critical reference for reconstructing ancient environments from fossil pollen retrieved in this region.

Oriented Generation of Novel Thermo-Sensitive Genic Male Sterile Lines with Improved Grain Shape and Outcrossing Rate in Early-Season Rice

Two-line hybrid rice with excellent quality is preferred in the Chinese market.However,there is a trade-off between reducing costs for hybrid seed production and lowering the outcrossing rate of the sterile line,which is largely determined by the stigma exsertion rate(SER).In this study,we constructed mutants of male sterility lines with improved grain length(GL)and SER in three elite early-season indica rice varieties through targeted manipulation of the TMS5 and GS3 genes using CRISPR/Cas9-mediated multiplex systems.We obtained a series of marker-free gs3 single mutants and gs3tms5 double mutants with significantly higher SER,longer grains,and increased 1000-grain weight compared with the wild type(WT).Importantly,the typically thermo-sensitive genic male sterile(TGMS)trait with a higher SER was observed in gs3tms5 mutants,and their F1 hybrids exhibited remarkable improvements in grain shape and yield-related traits.Our findings provided an efficient method to generate new valuable TGMS germplasm with improved SER through the mutagenesis of GS3 and TMS5 synergistically,and demonstrated that GS3 had pleiotropic effects on grain size,SER,and grain quality in early-season indica rice.

Increased sugar content impairs pollen fertility and reduces seed-setting in high-photosynthetic-efficiency rice

Crop yield depends on biomass,which is primarily associated with photosynthesis.We previously demonstrated that two photorespiratory bypasses,i.e.,GOC(glycolate oxidase+oxalate oxidase+catalase)and GCGT(glycolate oxidase+catalase+glyoxylate carboligase+tartronic semialdehyde reductase),significantly increased photosynthesis,biomass,and grain yield,but decreased seed-setting rates in rice.This study explored the underlying mechanism of how elevated photosynthetic efficiency impacted the seed-setting.First,pollen germination assessed in vivo and in vitro,revealed a reduced germination rate in GCGT rice.Subsequent analysis found that photosynthates highly accumulated in the leaves and stems;sucrose and soluble sugar levels were increased but the starch level was reduced in the anthers.Uridine diphosphate glucose(UDP-Glc)was increased but uridine diphosphate galactose(UDP-Gal)was unaltered,thus causing an imbalance in the UDP-Glc/UDP-Gal ratio in GCGT anthers.Most anthers in GCGT plants had two locules in contrast to four in the wild-type(WT).Pollen tapetum was developmentally abnormal,and genes related to sucrose synthesis,transport,and tapetal programmed cell death(PCD)were upregulated,whereas those involved in starch synthesis and conversion were downregulated in GCGT anthers.Taken together,our results demonstrated that an increase in sugar content was the primary factor causing reduced seed-setting rates in high photosynthetic efficiency rice,during which metabolic disorder of sugars and UDP sugar imbalance in anthers lead to impaired pollen fertility.

Comparative Study on Floral Organs and Pollen Characteristics of Different Varieties of Sorrel

The floral organ morphology,pollen morphology,quantity,and viability of Rumex,Rumex hanus F1,Rumex hanus 1,and Rumex hanus 2 were compared and analyzed.The results showed that the longitudinal diameter of petals was not significantly different among different varieties of sorrel,and the transverse diameter and corolla diameter showed differences to varying degrees.They all had six stamens and three stigmas.The pollen shape of the four varieties was prolate,and the polar view was trilobated and round.They all had three germinal furrows,and the outer wall of the pollen was decorated with small cavities and spiny patterns,with warty protrusions.The equatorial axis length of pollen of different varieties of sorrel was significantly different(P<0.05).There were no significant differences in pollen amount among different varieties.There were six anthers in a single flower,featuring anther dehiscence.The pollen viability of Rumex hanus 1 was significantly lower than that of the other three varieties(P<0.05).Therefore,through the analysis of the floral organs and morphological characteristics of anthers of sorrel,the varieties of sorrel can be effectively distinguished and identified.

Treatments of Pollen with Different Solvents Affect the Seed Setting Rate of Rice(Oryza sativa L.)

This study aimed to investigate the effects of treatments of rice pollen with different solvents on the seed setting rate.Rice pollen was treated with ultrapure water,0.5%dimethyl sulfoxide,ethanol(1%,5%,and 8%),and 0.5%dimethyl sulfoxide+8%ethanol,and the pollen without treatment was taken as the control.Then,crossing was conducted with the treated rice plants as the male parents and plants subjected to emasculation by warm water as the female parents.The seed setting rates of the male and female parents were then recorded.The results showed that the treatments with different solvents significantly decreased the seed setting rates of both male and female parents.The treatment with 1%ethanol resulted in the highest seed setting rates for both male and female parents,while the treatment with 0.5%dimethyl sulfoxide resulted in the lowest seed setting rates for both parents.Although these solvents affected the seed setting rate of rice,they served as intermediate solvents to dissolve chemicals used in the induction of rice haploids.This study layed a technical foundation for subsequent chemical induction of rice haploids.

Rice AGL1 determines grain size and sterile lemma identity

The grass spikelet is a unique inflorescence structure that determines grain size.Although many genetic factors have been well characterized for grain size and glume development,the underlying molecular mechanisms in rice are far from established.Here,we isolated rice gene,AGL1 that controlled grain size and determines the fate of the sterile lemma.Loss of function of AGL1 produced larger grains and reduced the size of the sterile lemma.Larger grains in the agl1 mutant were caused by a larger number of cells that were longer and wider than in the wild type.The sterile lemma in the mutant spikelet was converted to a rudimentary glume-like organ.Our findings showed that the AGL1(also named LAX1)protein positively regulated G1 expression,and negatively regulated NSG1 expression,thereby affecting the fate of the sterile lemma.Taken together,our results revealed that AGL1 played a key role in negative regulation of grain size by controlling cell proliferation and expansion,and supported the opinion that rudimentary glume and sterile lemma in rice are homologous organs.