Silique length influences seed yield in oilseed rape.It shows extensive variation in germplasm resources,and identifying the underlying genes and regulatory mechanisms would advance breeding for the trait.In the present study,a genome-wide association study(GWAS)using 331 core accessions planted in 10 environments revealed 13 loci associated with silique length on chromosomes A01,A04,A07,A09,and C03,explaining 6.2％-19.2％of phenotypic variance.Physiological analysis showed that silique length variation was attributable to differences in silique growth rate and/or duration before four weeks after flowering,with levels of endogenous phytohormones(auxin,ethylene,and GA24,GA12,and GA44)play-ing an important role.Cytological analysis showed that silique length variation was due mainly to differ-ences in cell number followed by cell size.Transcriptomic analysis of two pools of silique walls with opposite length extremes revealed 3248 differentially expressed genes(DEGs).These DEGs were enriched in several pathways(such as cell wall,cell division,and hormone metabolism)associated with cell pro-liferation and expansion and silique development.Integrating GWAS,RNA-seq,and functional annotation results revealed 15 candidate genes for the major associated locus qSL.A09-3.Of these,BnaA9.ARF18 and BnaA9.CYP78A9 were validated by haplotype analysis followed by candidate gene association.Sequence variation in the coding region of BnaA9.ARF18 and expression of BnaA9.CYP78A9 in silique walls were strongly associated with silique length.Our results provide an explanation for the natural variation of sili-que length in oilseed rape germplasm and offer useful information for its improvement.

Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences,Key Laboratory of Biology and Genetic Improvement of Oil Crops,Ministry of Agriculture and Rural Affairs,Wuhan 430062,Hubei,China

[1]Quaid Hussain;Jiepeng Zhan;Huabing Liang;Xinfa Wang;Guihua Liu;Jiaqin Shi;Hanzhong Wang-.Key genes and mechanisms underlying natural variation of silique length in oilseed rape(Brassica napus L.)germplasm)[J].作物学报（英文版）,2022(03):617-626

Silique,GA24,GA12,GA44,qSL,BnaA9,ARF18,CYP78A9,sili

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