基于GWAS和RNA-seq解析中国芒耐重金属铬分子机制

In recent years, the increasing soil heavy metal pollution, including hexavalent chromium, has become a serious threat to agricultural production. The use of plants for heavy metal contaminated soil repair is cost effective and ecological benefits. Miscanthus sinensis is one of the most potential plants for heavy metal contaminated soil repair, with strong tolerance to heavy metal hexavalent chromium and abundant biomass. However, the molecular mechanisms of tolerance to heavy metals hexavalent chromium are not entirely clear. Based on the collection and evaluation for a large number of M. sinensis germplasm resources, the project is designed to: 1) conduct the phenotypic and genetic evaluation of M. sinensis to heavy metal chromium stress and identify differentially expressed genes based on RNA-seq, discovery the molecular mechanisms of tolerance to heavy metal hexavalent chromium stress in resistance /sensitive genotypes; 2) construct the population for association analysis, genotyping by GBS-SNP and LD analysis; 3)determine and clone the major gene associated with heavy metal hexavalent chromium stress by combining genome-wide association (GWAS) analysis and RNA-seq. The results of the project will provide valuable basis materials and technical support for future evaluation and utilization of M. sinensis resource contributing to molecular breeding.

近年来土壤重金属铬污染严重威胁农业生产，利用植物进行重金属污染土壤修复成本相对较低，且具有良好的生态效益。中国芒(Miscanthus sinensis)具有较强的耐重金属铬特性，是修复污染土壤最有潜力的多年生作物之一，然而其耐重金属分子机制尚未完全明确。本项目拟在前期收集、评价大量中国芒资源的基础上，1）系统分析重金属铬胁迫对中国芒地上及地下部分的影响，筛选对重金属铬耐/敏感材料，利用高通量转录组深度测序技术(RNA-Seq)挖掘差异表达基因，进行网络共表达分析；2）构建关联作图群体，对关联群体进行全基因组GBS-SNP、SSR基因型鉴定及全基因组关联分析(GWAS)；3）联合RNA-Seq与GWAS挖掘调控主效基因，揭示中国芒耐重金属铬分子机制。研究结果可为今后中国芒耐重金属铬胁迫分子育种提供重要的材料及理论支撑。

中国芒极耐重金属铬，被认为是矿山废弃地生态治理和污染土壤修复的最主要植物之一。本项目立足于西南区丰富的中国芒资源，进行了核心种质资源收集及耐重金属铬评价，结果表明，200 mg/L Cr6+处理后，中国芒植株根系为Cr6+积累的主要器官，主要集中在细胞壁和可溶性部位，而茎叶中Cr6+主要集中在可溶性部位，推测中国芒主要通过根组织细胞壁区隔及螯合作用降低铬离子毒害。此外，利用高通量转录组测序（RNA-seq）和 miRNA 测序对芒在铬胁迫后不同时间点的基因表达调控进行研究，挖掘相关重要候选基因，揭示芒耐重金属铬的分子调控机制，其中谷胱甘肽代谢和ABC转运蛋白通路在中国芒耐Cr6+中起重要作用。同时硫酸盐转运蛋白ST在参与Cr6+吸收、转运机制也中具有重要作用。miRNA 测序表明miR156a、miR164、miR396d和novel_miR155参与植物Cr的生理生化代谢和解毒。研究结果为候选基因的验证和耐重金属铬中国芒品种的选育提供了分子和遗传基础。依托本项目相关研究结果共发表SCI收录论文4篇，CSCD收录论文2篇，授权发明专利1项，实用新型专利1项，培养毕业硕士研究生2名。