玉米幼胚胚性愈伤组织诱导能力全基因组遗传解析

The induce process of embryonic callus from maize embryo is the core technology in GMO industry. But due to the lack of core inbred lines with high induction efficiency for embryonic callus, the development of maize transgenic breeding was inhibited seriously. In this study, we will combine the high genetic resolution map in IBM population and genome-wide association mapping study, identify and verify the candidate genes with highly significant SNPs and QTLs which related to the trait of high induction efficiency of maize embryonic callus. First of all, we will generate a high density genetics map with 6618 bin markers in a 280 lines IBM Syn10 DH population, with mixed different environment and locations phenotype data to fine mapping the major QTLs. Meanwhile, we are going to use high-resolution SNP microarray for further association study in a 300 hundreds inbred lines population, for the goal of identifying significant SNPs and important candidate genes with the collaboration with DuPont Pioneer. By the method of comparative genomics and bioinformatics, we aim to identify excellent alleles. We also plan to clone these genes from the maize inbred lines with high induction rate of embryonic callus.Then, the functions of the above cloned genes will be validated by both transgenic and TALEN technologies. Combined with previous researches on microRNA regulation and gene expression of embryonic callus induction process, the project will be intended to construct genetic and regulatory networks of induction ability for maize embryonic callus on the whole-genome level.

玉米胚性愈伤组织诱导是转基因技术的关键环节，我国高胚性愈伤诱导率骨干自交系匮乏，严重阻碍了转基因育种的快速发展。本项目拟采用高覆盖率重测序构建的玉米IBM连锁图谱及全基因关联分析，深入挖掘与玉米高胚性愈伤诱导率显著相关的SNP标记和QTL位点，验证候选基因功能。首先以包含280份DH系的IBM Syn10群体及其构建的6618个bin marker基因型数据为基础，结合多年多点表型鉴定精细定位高胚性愈伤诱导率QTL区间，发掘控制玉米高胚性愈伤诱导率的关键候选基因。再利用先锋公司开发的高密度SNP芯片对300份玉米自交系进行全基因组关联分析，鉴定与高胚性愈伤诱导率显著相关的SNP位点和关键基因。并利用比较基因组、生物信息学手段，确定并克隆优良等位基因，进而通过转基因和TALEN定点突变验证候选基因功能。结合前期对胚性愈伤诱导过程基因表达调控研究，对玉米胚性愈伤诱导能力进行遗传和调控网络解析。

鉴定控制玉米胚性愈伤组织诱导关键基因，阐明愈伤组织形成的分子机理，为培育更多高胚性愈伤组织诱导率骨干自交系提供理论支持, 为加快转基因玉米育种进程奠定基础，另一方面也能促进整个基因功能研究领域的快速发展。本项目以玉米胚性愈伤组织诱导率为直接目标性状，一方面利用双亲在胚性愈伤组织诱导性状上存在显著差异的高重组率 IBM Syn10 DH群体，在多环境下对控制玉米胚性愈伤组织诱导率进行了QTL 定位。另一方面，利用 361 份自交系进行了多环境下胚性愈伤诱导率的全基因组关联分析，鉴定与目标性状显著相关的 SNP 位点。结合QTL定位和GWAS分析结果在全基因组水平上解析了控制玉米胚性愈伤组织诱导率的遗传基础，挖掘了控制目标性状的候选基因。并对生长激素信号传导通路的ZmSAUR基因进行候选基因的关联分析，鉴定了候选基因的优异单倍型。通过转基因过表达、突变体以及CRISPR/Cas9双向验证了ZmSAUR对玉米胚性愈伤组织诱导的调控功能。利用基因共表达技术鉴定并验证了ZmSAUR 基因的互作基因及调控网络。项目成果为培育高胚性愈伤诱导率骨干系,提高玉米遗传转化效率，加快转基因玉米育种进程，促进玉米基因功能解析做出了重要贡献。