大豆根茎过渡区弯曲突变体M_(rstz)的鉴定与基因定位

Identification and gene mapping of soybean mutant M_(rstz) in root-stem transition zone

植物根茎过渡区(root-stem transition zone,RSTZ)将根和茎相互连接,其发育形态决定了大豆的地上部株型和抗倒伏潜力。本研究通过EMS诱变获得一个RSTZ弯曲或旋转的大豆突变体M_(rstz),其形态特征能够稳定遗传,是探究大豆茎秆发育规律的特异材料。将该突变体和栽培大豆中黄13杂交构建重组自交系群体,对群体中直立和弯曲型后代的RSTZ进行解剖结构比较,发现弯曲型株系比直立型株系的维管形成层较宽、次生木质部细胞层数较多、细胞形状不规则,表明维管组织分化可能是导致RSTZ形态发生差异的重要因素之一。进一步对化学组分测定发现,木质素和粗纤维含量越高越不易弯曲。选取RIL群体中弯曲型和直立型2种极端株系进行BSA-Seq,采用SNP-index和InDel-index关联分析方法鉴定到调控RSTZ形态的关联区域Chr19:43030943~45849854,该区间共含有319个基因。结合生物信息学分析、基因注释信息和表达丰度分析筛选到7个候选基因,分别为Glyma.19G170200、Glyma.19G201500、Glyma.19G187800、Glyma.19G178200、Glyma.19G197000、Glyma.19G179100、Glyma.19G196900。其中,Glyma.19G187800、Glyma.19G178200和Glyma.19G196900在大豆驯化中潜在影响RSTZ形态建成。本研究为解析大豆RSTZ组织形成及其遗传基础提供了材料基础,并为挖掘调控大豆茎秆发育基因提供新的见解。

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 M_(rstz),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 vascular 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 domestication.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.