Identification of a candidate QTG for seed number per silique by integrating QTL mapping and RNA-seq in Brassica napus L.

Seed number per silique(SNPS)is one of seed yield components in rapeseed,but its genetic mechanism remains elusive.Here a double haploid(DH)population derived from a hybrid between female 6Q006with 35–40 SNPS and male 6W26 with 10–15 SNPS was investigated for SNPS in the year 2017,2018,2019 and 2021,and genotyped with Brassica 60K Illumina Infinium SNP array.An overlapping major QTL(qSNPS.C09)explaining 51.50%of phenotypic variance on average was narrowed to a 0.90 Mb region from 44.87 Mb to 45.77 Mb on chromosome C09 by BSA-seq.Subsequently,two DEGs in this interval were detected between extreme individuals in DH and F_2populations by transcriptome sequencing at7 and 14 days after pollination siliques.Of which,BnaC09g45400D encoded an adenine phosphoribosyltransferase 5(APT5)has a 48-bp InDel variation in the promoter of two parents.Candidate gene association analysis showed that this InDel variation was associated with SNPS in a nature population of rapeseed,where 54 accessions carrying the same haplotype as parent 6Q006 had higher SNPS than103 accessions carrying the same haplotype as parent 6W26.Collectively,the findings are helpful for rapeseed molecular breeding of SNPS,and provide new insight into the genetic and molecular mechanism of SNPS in rapeseed.

Effects of Plant Spacing,Row Spacing and Seedling Number Allocation on the Growth Dynamics of Different Populations of Two Types of Rice Varieties

[Objectives]This study was conducted to construct high-yielding,high-quality,and high-light-efficiency population structures of different types of rice varieties.[Methods]The effects of plant spacing,row spacing and seedling number allocation on stems and tillers,leaf area and dynamic traits of high-yielding rice populations(more than 9750 kg/hm^(2))and low-yielding populations(less than 9750 kg/hm^(2))were studied by two kinds of representative rice varieties with different tiller ability and panicle sizes in cold regions.[Results]Decreasing the plant and row spacing and increasing the number of planted seedlings per hole advanced the heading date and made the number of stems and tillers in the population increase.The impact on the super rice variety with fewer tillers and heavier panicles was greater than that of conventional variety with more tillers and lighter panicles.The stems and tillers of the high-yielding high-quality populations grew steadily in the early stage of development,until an appropriate number of panicles was reached at the critical leaf age for productive tillers(June 25),and the peak seedlings should appear in the jointing stage(July 9)with a small number(that value of Longjing 21,the super rice variety with fewer tillers and heavier panicles,was about 1.2 times the expected panicle number,and that of the conventional variety with more tillers and lighter panicles,Kongyu 131,was about 1.1 times the expected panicle number).The populations gradually declined since then,until reaching an appropriate number of panicles at the heading stage.The high-yielding high-quality populations had a higher leaf area index at the heading stage.The value of Longjing 21,the super rice variety with fewer tiller and heavier panicles,reached about 6.0,and that of Kongyu 131,the conventional variety with more tillers and lighter panicles,reached about 4.5.The values decreased thereafter.At the maturation stage,the leaf area index of Longjing 21 remained above 2.5,and that of Kongyu 131 remained above 2.0.[Conclusions]This study has an important guiding role and significance for their high-yielding and high-quality supporting cultivation in cold regions.

Effects of grazing intensity on seed production of Caragana stenophylla along a climatic aridity gradient in the Inner Mongolia Steppe,China

As the increases of climatic aridity and grazing intensity, shrubs play an increasingly important role in grassland ecosystem in arid and semi-arid regions, and its abundance also generally increases. However, the effects of climatic aridity and grazing intensity on sexual reproduction of shrubs in grassland remain largely unclear. In order to understand the effects of grazing intensity and climatic drought stress, and their interaction on seed production of shrub species, we examined the seed number, seed weight and seed yield of Caragana stenophylla under three grazing intensities （fenced, mild grazing and severe grazing） across a climatic aridity gradient （semi-arid, arid, very arid and intensively arid zones） in the Inner Mongolia Steppe, northern China during 2012-2013. The seed number, seed weight and seed yield gradually increased from the semi-arid to the very arid zones, but decreased from the very arid to the intensively arid zones in fenced plots. The seed number and seed yield decreased from the semi-arid to the intensively arid zones in mild and severe grazing treatment plots, therefore, grazing enhanced the suppression effect of climatic aridity on seed production of C. stenophylla. The seed number and seed yield gradually decreased as grazing intensity increased. The seed weight was highest in severe grazing plots, followed by the mild grazing plots and then the fenced plots. Precipitation varied interannually during the study period. We observed that the seed number seed weight and seed yield were lower in the low precipitation year （2013） than in the high precipitation year （2012）. As climatic drought stress increased, the negative effects of grazing on seed production of C. stenophylla also gradually increased. Our results indicated that climatic drought stress may contribute to the encroachment of C. stenophylla shrub in arid zones by promoting its seed production. However, grazing had negative effects on sexual reproduction of C. stenophylla, and the combined effects of drought stress and grazing seriously suppressed sexual reproduction of C. stenophylla in the intensively arid zone.

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.

BR Signal Influences Arabidopsis Ovule and Seed Number through Regulating Related Genes Expression by BZR1

Ovule and seed developments are crucial processes during plant growth, which are affected by different signaling pathways. In this paper, we demonstrate that the brassinosteroid （BR） signal is involved in ovule initiation and development. Ovule and seed numbers are significantly different when comparing BR-related mutants to wild-type con-trols. Detailed observation indicates that BR regulates the expression level of genes related to ovule development, includ-ing HLL, ANT, and AP2, either directly by targeting the promoter sequences or indirectly via regulation by BR-induced transcription factor BZR1. Also, Western blot demonstrates that the dephosphorylation level of BZR1 is consistent with ovule and seed number. The intragenic bzrl-lD suppressors bzs247 and bzs248 have much fewer ovules and seeds than bzrl-lD, which are similar to wild-type, suggesting that the phenotype can be rescued. The molecular and genetic experi-ments confirm that BZR1 and AP2 probably affect Arabidopsis ovule number determination antagonistically.

Interaction of brassinosteroid and cytokinin promotes ovule initiation and increases seed number per silique in Arabidopsis

Ovule initiation is a key step that strongly influences ovule number and seed yield.Notably,mutants with enhanced brassinosteroid(BR)and cytokinin(CK)signaling produce more ovules and have a higher seed number per silique(SNS)than wild-type plants.Here,we crossed BR-and CKrelated mutants to test whether these phytohormones function together in ovule initiation.We determined that simultaneously enhancing BR and CK contents led to higher ovule and seed numbers than enhancing BR or CK separately,and BR and CK enhanced each other.Further,the BR-response transcription factor BZR1 directly interacted with the CK-response transcription factor ARABIDOPSIS RESPONSE REGULATOR1(ARR1).Treatments with BR or BR plus CK strengthened this interaction and subsequent ARR1 targeting and induction of downstream genes to promote ovule initiation.Enhanced CK signaling partially rescued the reduced SNS phenotype of BR-deficient/insensitive mutants whereas enhanced BR signaling failed to rescue the low SNS of CK-deficient mutants,suggesting that BR regulates ovule initiation and SNS through CK-mediated and-independent pathways.Our study thus reveals that interaction between BR and CK promotes ovule initiation and increases seed number,providing important clues for increasing the seed yield of dicot crops.

Ovule initiation:the essential step controlling offspring number in Arabidopsis

Seed is the offspring of angiosperms.Plants produce large numbers of seeds to ensure effective reproduction and survival in varying environments.Ovule is a fundamentally important organ and is the precursor of the seed.In Arabidopsis and other plants characterized by multi-ovulate ovaries,ovule initiation determines the maximal ovule number,thus greatly affecting seed number per fruit and seed yield.Investigating the regulatory mechanism of ovule initiation has both scientific and economic significance.However,the genetic and molecular basis underlying ovule initiation remains unclear due to technological limitations.Very recently,rules governing the multiple ovules initiation from one placenta have been identified,the individual functions and crosstalk of phytohormones in regulating ovule initiation have been further characterized,and new regulators of ovule boundary are reported,therefore expanding the understanding of this field.In this review,we present an overview of current knowledge in ovule initiation and summarize the significance of ovule initiation in regulating the number of plant offspring,as well as raise insights for the future study in this field that provide potential routes for the improvement of crop yield.

Seed size-and density-related hidden treatments in common biodiversity experiments

Aims With a few exceptions,most well-known field biodiversity experiments on ecosystem functioning have been conducted in plant communities(especially grasslands)in which different numbers of species are planted as treatments.In these experiments,investigators have either kept the total seed weight or seed number constant across treatment plots.However,although in some cases attempts have been made to randomly choose species for planting from a designated species pool,the issue of possible‘hidden treatments’remains unsolved.Particularly,the total and relative abundance among species and across treatments could still affect the results.This study aims to determine whether treatments related to planted seed abundance and seed size may contribute to observed productivity.Methods We re-analyzed data from four biodiversity experiments based on a common seeding design(i.e.diversity treatments).Important Findings We show that diversity(richness)treatments usually involve a hidden treatment related to the planted seeds(i.e.weight,number and seed size)that ultimately affect plant density.Thus,the un-intended hidden treatment of seeding more seeds on more diverse plots contributes to the productivity to some degree.Such derivative but often neglected hidden treatments are important for further improvement of experimental design and have significant implications in ecological restoration.