外源高钙调控喜钙植物短叶黄杉抗干旱胁迫的生理及分子机制

Drought and high calcium in Karst soil are important limiting factors of rocky desertification revegetation in southwest China. However, there is a close relationship between high calcium concentrations in Karst soil and drought resistance of calcicole. However, the internal mechanism underling it still need a further study. In this project, we use Pseudotsuga brevifolia Karst calcicole as the research material. After treated with different concentrations of calcium and drought stress, the photosynthetic characteristics and osmoregulation substance content, protective enzyme activity will be measured to clear the effects of exogenous calcium on the physiological mechanism of drought resistance in Pseudotsuga brevifolia. At the same time, the transcriptomic and proteomic analysis of Pseudotsuga brevifolia under different treatments will also be undertook by using ITRAQ, LC - MS/MS and RNA-seq technologies and calcium regulatory genes or proteins related to drought resistance will be excavated. Moreover, the expression patterns of these genes and proteins will be detected at mRNA or protein levels with the help of qRT - PCR and Western Blot technologies. The relationship between characters of physiological responses and expression features of drought resistant related genes or proteins will be analyzed. Then, the way by which calcicole can utilize the exogenous high calcium to induce or regulate the expression of genes or proteins involved in drought resistance and effect plant drought tolerance at physiological level. Thus, the molecular mechanism of calcicole drought resistance regulated by karst high calcium will be clarified. In conclusions, the result of this research will provide a significant reference for stress resistance breeding and cultivation measure modification in the process of revegetation of karst rocky desertification.

西南喀斯特土壤的干旱及高钙特征是石漠化植被恢复的重要限制因素。然而喀斯特土壤高钙与喜钙植物的抗旱性又存在紧密联系，其内在机制尚待深入。本项目以喀斯特喜钙植物短叶黄杉为对象，检测幼苗叶片在不同浓度钙及干旱处理后的光合特征、渗透调节物含量、保护酶活性等指标，明确外源钙影响短叶黄杉抗旱性的生理机制，同时利用ITRAQ、LC-MS/MS及RNA-seq技术，研究短叶黄杉叶片在不同处理下的转录组及蛋白组响应特征，挖掘与抗旱相关的钙调控基因蛋白，借助qRT-PCR及Western Blot技术从mRNA转录和蛋白质水平检测这些差异基因蛋白的表达特征，综合分析生理响应特征与抗旱相关基因蛋白表达特征之间的关系，探讨外源高钙如何调控喜钙植物抗旱相关基因蛋白的表达水平，进而从生理水平影响其抗旱性，最终揭示喀斯特高钙生境调控喜钙植物抗旱的分子机制。这将为石漠化植被恢复过程中的抗逆育种及栽培措施改良提供重要参考。

喀斯特地区的高钙环境与钙生植物的抗旱性存在着紧密关系，其内在机制尚待深入。项目以喀斯特喜钙植物为材料，开展其在干旱（PEG-6000）及钙处理下的生理生化、转录组及蛋白组学响应特征，结果发现外源钙能够通过改善水分状况、提升渗透调节物质含量、活性氧清除能力及光合效率来提升喜钙植物的抗旱能力；通过开展转录组学分析发现，大量涉及渗透调节（GLOS, FDA,LTP,CAD等），抗氧化胁迫（GLP，POD）及钙离子感受（CAM、CML3、CML43）相关基因在外源钙处理后均显著上调表达，而在钙离子螯合剂（EGTA）及钙通道阻滞剂（Lacl3）处理下均不同程度下调表达；结合iTRAQ同位素标记技术开展蛋白质组学分析发现，大量涉及渗透调节（PEPC4，NADP-ME，FDA，SPP2，SUS1，PPC），抗氧化防御（Prx, MSRB1, ICDH, CBSX3, DFR, TP53I3）以及光合作用（OMT1, PEPC4, NADP-ME, FTRC）相关的蛋白在外源钙及EGTA处理后分别呈现不同程度的上调及下调表达，上述结果表明外源钙能够通过调控植物渗透调节、活性氧清除、光合作用及其他抗旱相关蛋白基因的表达进而提升喜钙植物的抗旱能力，研究结果有助于阐明喜钙植物在喀斯特高钙、干旱生境下的适应性机制，为喀斯特石漠化植被恢复过程的抗逆育种和栽培措施改良提供重要参考。