盐胁迫下白刺蜡质沉积分子网络调控机制研究

Halophytes can deposit a lot of cuticular wax in saline environment, which is closely related to its adaptation to the saline environment. However, research on the mechanism of molecular network regulation for this adaptation is obscure yet, and the influence of wax deposition on salinity tolerance of halophytes to be determined. So in this project, first of all, to reveal the mechanism of molecular network regulation for wax deposition under salt stress, with Nitraria tangutorum, which is a halophyte of significant wax deposition as materials, the dynamic changing of transcriptome expression profile of Nitraria tangutorum during salt stress is analyzed, with correlation analysis of differentially expressed genes carried out in combination with the wax deposition data. Secondly, NtCER1, the key gene in the wax biosynthetic pathway, is cloned, with the gene kept silent via RNA interference, and the impact of wax deposition in salt stress on the salinity tolerance of Nitraria tangutorum is revealed in combination with physiological and biochemical analysis. These results will provide the theoretical basis for preliminarily revealing the molecular network regulation mechanism of wax deposition of halophytes in the saline environment or under salt stress, and the impact of wax deposition on the salt tolerance of halophytes. It is significant for resolving the salt tolerance mechanism of halophytes in the perspective of wax, as well as the genetic improvement of crops, trees and pasture in salinization areas.

盐生植物在盐生环境中能够沉积大量的表皮蜡质，这与其适应盐生环境有很大关系。然而，目前这一适应性分子网络调控机制的研究尚不清楚，且蜡质沉积对盐生植物耐盐性的影响未被确证。因此，本项目拟以在盐胁迫下蜡质沉积明显的盐生植物白刺为研究材料，首先，分析白刺在盐胁迫过程中的转录组表达谱动态变化规律，并结合蜡质沉积测定结果对差异表达基因进行关联性分析，以初步揭示白刺在盐胁迫下蜡质沉积的分子网络调控机制。其次，克隆蜡质合成途径中的关键基因NtCER1，利用RNAi干扰手段沉默该基因来抑制蜡质的合成，并结合生理生化分析揭示盐胁迫下蜡质沉积对白刺耐盐性的影响。研究结果将为解析盐生植物在盐生环境或盐胁迫下蜡质沉积的分子网络调控机制以及蜡质沉积对盐生植物耐盐性的影响提供理论依据。这对从蜡质角度解析盐生植物耐盐机制，以及对盐渍化地区农作物、林木及牧草的遗传改良具有重要意义。

盐生植物在盐生环境中能够沉积大量的表皮蜡质，这与其适应盐生环境有很大关系。然而，目前这一适应性分子网络调控机制的研究尚不清楚，且蜡质沉积对盐生植物耐盐性的影响未被确证。为解决上述问题，本项目开展了一系列研究并取得以下主要结果：（1）盐胁迫下白刺表皮堆结大量蜡质颗粒，蜡质总含量增加，其中C31烷类含量最高且高于对照组；（2）碱性盐胁迫下，白刺转录组中发现大量与蜡质相关的差异基因，9个比较组中的差异基因显著富集于“角质层、软木脂和蜡质生物合成”KEGG通路；（3）基于转录组数据推测出一个由4条通路组成的蜡质调控网络模型；（4）克隆获得白刺NtCER1基因CDS序列，全长1590bp；（5）亚细胞定位初步判定NtCER1蛋白主要定位于拟南芥细胞质和内质网中；（6）超表达NtCER1的拟南芥茎表皮中蜡质沉积表型明显；（7）拟南芥超表达株系茎中的酮类蜡质显著高于野生型植株，而醛类显著低于野生型植株；（8）盐胁迫下，转基因拟南芥的表型和生理指标均证明超表达NtCER1提高了拟南芥的耐盐性。