大豆根茎过渡区弯曲突变体Mrstz的鉴定与基因定位OA北大核心CSTPCD

Root-stem transition zone(RSTZ)connects roots and stems,and its morphology modifies the structure of aerial part and lodging resistance potential in soybean.In this study,a soybean mutant Mrstz,appearing with curved or rotated RSTZ,was obtained by EMS mutagenesis.Its morphological characteristics were stably inherited and could provide specific sources for exploring the development patterns of soybean stems.Therefore,this mutant was crossed with Zhonghuang 13 to construct a recombinant inbred line population.By comparing the anatomical structure of vertical RSTZ and curved RSTZ,the wider vascular cambium,more secondary xylem cell layers and irregular cell shape were identified in curved lines,indicating that vas-cular cambium differentiation may be one of the important factors leading to the difference of RSTZ morphology.Subsequently,the chemical compositions of lines with vertical RSTZ or curved RSTZ were determined,respectively.It was found that the higher lignin and crude fiber content in the RSTZ,the more difficult to bend.The RSTZ with curved or vertical lines were further selected for BSA-seq.SNP-index and InDel-index methods were employed to mine a significant association region,Chr.19:43,030,943-45,849,854 containing 319 genes,which may regulate RSTZ morphology.Combined bioinformatics analysis,gene annotation information and expression abundance analysis,seven candidate genes(Glyma.19G170200,Glyma.19G201500,Glyma.19G187800,Glyma.19G178200,Glyma.19G197000,Glyma.19G179100,Glyma.19G196900)were screened.Among them,Glyma.19G187800,Glyma.19G178200,and Glyma.19G196900 potentially affected RSTZ morphogenesis in soybean domestica-tion.This study not only provides germplasm resources for the understanding of soybean RSTZ tissue formation and its genetic basis,but also provides new insights for further exploration of genes regulating soybean stalk development.