复苏植物牛耳草耐脱水性获得与维持过程的代谢调控网络分析

The Gesneriaceae resurrection plant species Boea hygrometrica is able to survive moderate water loss up to 95% relative water content and acquired desiccation tolerance to rapid dehydration after drought acclimation, thus serves as a model system to investigate the response mechanism to severe dehydration as well as the study of the drought-resistance genes. Recent studies have revealed large-scale reprogramming of the B. hygrometrica transcriptome associated with multiple primary and secondary metabolism in response to desiccation and rehydration, yet, the mechanism for metabolic regulation remains practically unknown. This project will apply a comprehensive metabolome study during the acquisition and maintenance of desiccation tolerance in B. hygrometrica leaves, DNA methylome and transcriptome-based regulatory network analysis of metabolism, as well as in vivo functional verification of desiccation tolerance-related genes and corresponding metabolites. Systematic methods and techniques such as multi-omic data integration, plant transgenic, physiological and biochemical analyses will be used to illustrate the metabolic regulation networks during the process of plant adaptation to drought stress. Consequently, the results of this project tends to unravel the comprehensive mechanism of drought resistance in plants and will provide a theoretical foundation in breeding of drought-resistant crops.

苦苣苔科复苏植物牛耳草具有极强的干旱抗性，脱水95%以上仍能存活，且经历土壤慢速干旱锻炼后能够获得并维持耐快速脱水能力，是研究植物抗旱机制和挖掘抗旱基因的理想材料。前期研究发现，牛耳草在脱水和复水过程中，大量初生以及次生代谢途径相关基因的表达发生显著变化，但其代谢产物积累及调控机理尚不明确。本项目拟在前期工作的基础上，以干旱锻炼诱导的牛耳草耐脱水性获得及维持体系为实验对象，着重开展以下三方面的研究：(1)检测牛耳草干旱锻炼过程的代谢组变化，筛选关键代谢物质；(2)结合基因组DNA甲基化和转录组数据，分析牛耳草耐脱水性获得及维持过程的代谢调控网络并筛选关键调控基因；(3)通过体外处理及转基因手段验证关键基因及其相应代谢物质的抗旱功能。以上研究拟采用多组学联合分析、转基因以及生理生化检测等方法，系统阐明植物干旱逆境适应的代谢调控网络，为进一步揭示植物抗旱分子机制以及作物抗逆育种提供理论依据。

苦苣苔科复苏植物牛耳草具有极强的干旱抗性，脱水95%以上仍能存活，且经历土壤慢速干旱锻炼后能够获得耐快速脱水能力，是研究植物抗旱机制和挖掘抗旱基因的理想材料。为了阐明干旱锻炼诱导的牛耳草耐快速脱水能力获得的分子基础，我们分析了牛耳草种子苗在土壤慢速干旱、复水以及干旱锻炼和未锻炼植株空气快速干旱过程的转录组变化。差异表达基因生物途径分析表明，干旱锻炼响应基因显著富集于植物激素信号转导以及初生代谢和次生代谢途径，表明牛耳草干旱锻炼过程涉及激素调控的代谢重组。基于基因表达谱分析结果，我们对牛耳草干旱锻炼和快速脱水胁迫过程的激素变化进行定量分析，并利用UPLC-MS/MS技术对植物材料进行广泛靶向代谢组分析。结果表明，顺式玉米素和反式玉米素两种类型细胞分裂素的含量在干旱锻炼和未锻炼植株空气快速干旱响应过程均升高，但变化程度在干旱锻炼植株中更显著；寡糖、类黄酮、香豆素、吲哚-3-甲醛、L-酪胺和鸟苷等22种代谢物质在干旱锻炼植株中的积累显著高于未锻炼植株，因此可作为耐快速脱水性相关生物标记。体外处理实验证明，外施蔗糖、海藻糖、异麦芽酮糖和乳糖等寡糖类物质均能显著提高牛耳草种子苗耐脱水能力，而吲哚-3-甲醛对牛耳草抗旱性无作用。此外，我们通过加权基因共表达网络分析筛选获得两个生物标记相关基因模块的核心基因，分别编码vacuolar protein sorting-associated protein 41和eukaryotic translation initiation factor 2D。本研究证明了干旱锻炼诱导的细胞分裂素和寡糖积累对牛耳草耐脱水性的重要影响，以上结果为揭示干旱锻炼诱导的植物抗旱性分子机理提供新证据，为作物抗旱栽培管理和分子育种技术提供新思路。

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