棉纤维初始发育应答镉胁迫的分子调控机理研究

Cadmium (Cd) is one of the most toxic heavy metals being contaminating our soils. It is therefore necessary to reduce soil Cd level to ensure the safety of agricultural products and ensure the sustainable and efficient use of the Cd contaminated soil. Cotton (Gossypium hirsutum L.) is one of the important fiber crops in the world, which is widely used for fiber production. It has higher potential for absorbing and removing Cd from moderately contaminated soils because of its large biomass. And the fiber has the lowest part in Cd accumulation than other organs. Thus it’s of great significance for efficient utilization and remediation of Cd contaminated soil by breeding and planting cotton cultivars. In this study, the Cd-tolerant and Cd-sensitive cotton cultivar namely SGK3 and TM-1 are utilized, which selected from the Cd polluted fields. We will explore the effects Cd stress on the expression level of endogenous hormone and fiber cell differentiation and protuberance in ovule, and aim to extensively analyze the transcriptomic and proteomic profile of cotton fiber initiation development, identify some regulatory genes related to Cd-tolerance by bioinformatics methods. We will further analyze the functions of the regulatory genes by cloning and transformation mediated by agrobacterium tumefaciens. The result of this research may provide valuable information for revealing the molecular mechanisms and regulation network of endogenous hormone, gene and protein expression responses to Cd stress in cotton fiber initiation development. It will lay foundation for breeding new cotton germplasm which have high-yield fiber and resistance to Cd stress, and then improve economic feasibility of remedying Cd contaminated soil.

镉是农田受污染最普遍的重金属之一。土壤镉修复已成为保证农产品质量安全和持续高效的利用土地资源的一项重要科学任务。棉花是重要的非食用性经济作物，其生物量大，对镉有较好的富集能力，而主产品棉纤维累积镉很少，培育和种植棉花品种对高效利用和治理镉污染土壤具有重要意义。本项目以前期筛选出耐镉性棉花品种SGK3以及对镉敏感的陆地棉标准系TM-1为材料，研究镉胁迫与胚珠内源激素表达以及纤维细胞分化和突起之间的关系，通过转录组分析和蛋白质差异表达分析，运用生物信息学技术筛选棉纤维初始发育应答镉胁迫的差异表达基因，克隆并验证其功能，明确棉纤维初始发育应答镉胁迫的分子调控机制，解析镉胁迫诱导激素、基因和蛋白质等在棉纤维初始发育过程中的调控网络，以期为培育纤维高产、植株耐镉的棉花新品种提供理论依据，进而提高修复镉污染土壤的经济可行性。

镉是农田受污染最普遍的重金属之一。棉花是较耐受非生物胁迫的作物且生物量大，主产品棉纤维具有非食用性，在兼顾生产和重金属污染治理方面具有独特优势。本研究以前期筛选出耐镉性棉花品种SGK3以及对镉敏感的陆地棉标准系TM-1为材料，分析了在开花-3、-1、0、1、2DPA时胚珠的激素变化规律，镉处理后激素GA、IAA和CTK含量呈缓慢上升趋势，ABA含量先下降之后缓慢上升，棉花胚珠激素含量与镉含量呈负相关，但不显著；细胞超微结构观察发现，镉胁迫引起纤维皱缩，日生长轮变得不明显，日生长轮和中腔窄缝颜色加深；全基因组甲基化分析表明，镉胁迫诱导棉花基因组DNA整体甲基化水平提高，CG、CHG和CHH类型甲基化的DMR显著富集的代谢通路有植物激素信号转导、半胱氨酸和甲硫氨酸代谢通路；构建了棉花胚珠响应镉胁迫的转录组表达谱，解析了棉花胚珠响应镉胁迫过程中差异基因表达变化，鉴定了陆地棉的植物络合素合酶GhPCS基因，分析了GhPCS基因在镉胁迫下的表达特性，GhPCS1、GhPCS2和GhPCS3在叶和根中下调表达，在根中表达下调量高于叶中。本研究结果在生理和分子水平上基本明确了棉纤维初始发育应答镉胁迫的时间表达和基因表达特点，为进一步深入开展棉花对镉胁迫的应答机制积累了较好的研究基础，为培育纤维高产、植株耐镉棉花新品种提供理论依据。