党参应对干旱胁迫的生理机制与水分利用策略研究

Water is the key ecological factors in the process of plant growth and development. Plants usually deal with bad environment through the responses and adaptive mechanism in the morphological, physiological and molecular level. Growth and metabolic process of medicinal plant will no doubt be affected by the changes of water, further the yield and quality will be affected. The drought has become the first threat to production of Codonopsis pilosula(Franch.)Nannf. and Codonopsis tangshen Oliv. with the geo-authentic habitats are migrated to the west. So, how does C.pilosula(Franch.)Nannf. and C.tangshen Oliv. answer to influence of drought in individual level and what changes has take place in water use strategy in the face of changes of abiotic factors-water. The research will be carried out with the mode of the box planting to control water and artificial simulated drought stress in the field. The changes of growth cycle, apparent character, physiological and biochemical characteristics, rule of material accumulation and main secondary metabolites of C.pilosula(Franch.)Nannf. and C.tangshen Oliv. in the drought stress will be researched. And the related genes response to drought stress and the expression of important key enzyme genes in the biosynthetic pathway of main secondary metabolites of C.pilosula(Franch.)Nannf. and C.tangshen Oliv.in the drought stress will be analyzed by the suppression subtractive hybridization and transcriptome sequencing.Thus clarifying adaptive mechanism response to drought stress and water use strategy of C.pilosula(Franch.)Nannf. and C.tangshen Oliv., to lay the theory foundation for exploring law of water demand, improving the yield and quality by water controlling, cultivating drought-tolerant varieties of C.pilosula(Franch.)Nannf. and C.tangshen Oliv..

水分是植物生长发育的关键生态因子，干旱条件下，植物一般通过形态、生理和分子水平的应答和适应机制来应对不良环境。水分变化无疑会影响药用植物生长发育和代谢过程，进而影响其产量和质量。伴随着党参道地产区西移，干旱已成为威胁党参生产的第一要素，那么党参在生长发育过程中面对非生物因子水分的变化，从个体水平上如何应对干旱造成的影响，其在水分利用策略方面又发生了哪些变化？本课题在农业生产的基础上采用箱栽控水和大田人工模拟干旱胁迫方式研究干旱胁迫条件下党参的生育周期、表观性状、生理生化特征、物质积累规律以及主要次生代谢产物的变化；并进一步利用抑制消减杂交技术和转录组测序技术，分析党参响应干旱胁迫相关基因以及党参主要次生代谢产物生物合成途径中重要关键酶基因的表达情况。以期阐明党参应对干旱胁迫的适应机制和水分利用策略，为探索党参生产需水规律、利用水分调节提高党参产、质量和培育党参耐旱品种奠定理论基础。

本课题主要通过研究干旱胁迫下党参的农艺性状变化特征、生物量（产量）与次生代谢产物（质量）的积累和分配规律，为道地产区整体西移后的优质党参高效生产奠定了基础。进一步分析了干旱胁迫下党参渗透调节物质、活性氧化酶和内源激素变化规律，并通过转录组学研究挖掘党参抗旱相关机制，为开展党参耐旱研究、生产和新品种培育提供理论依据。研究结果表明，党参的表观形态和干旱胁迫有显著相关性，随土壤水分的降低党参植株整体呈变矮趋势，其中地上部分比地下部分变化更为显著。在干旱胁迫过程中，党参调节地上部分和地下部分生长趋势，降低植株内自由水分的含量以应对干旱环境；并通过升高渗透调节物质含量、调节抗氧化酶类活性和改变激素的比例来应对干旱带来的损伤，调节自身生长，保障生命延续。代表有效组分和多糖的积累均在轻度胁迫条件下最大，中、重、极度干旱条件下各组分的积累趋于减少甚至出现抑制作用，仅丁香苷在极度胁迫时积累量最大。转录组学研究结果显示和党参响应干旱相关的差异表达基因共有1,359个，其中上调904个，下调455个。党参响应干旱胁迫的差异基因主要集中苯丙烷类生物合成（map00940）和淀粉/蔗糖代谢（map00500）等通路上，其中WRKY53和ACS1等8个基因可能是党参应对干旱的关键酶基因。在生产方面发现间歇性干旱后进行非充分补充灌溉可有效提高党参的产量和品质。通过高垄覆盖育苗技术、地表径流汇聚与收集系统的建立、秋季栽种技术与季节性补充灌溉技术和大田保墒技术等一系列技术的实施可很好的解决干旱地区党参生产受限以及季节性极端干旱等问题。