非特异脂质转运蛋白IlLTP1调控马蔺镉耐性和积累的作用机制

The phytoremediation of heavy metal contaminated soil is of great significance to the ecological environment construction. Iris lactea var. chinensis is a Cd-accumulating plant that can be applied to the phytoremediation of Cd-contaminated soil. It is of great value to study the mechanism of Cd tolerance and accumulation in I. lactea. In the previous study, we screened a Cd-induced non-specific lipid transfer protein IlLTP1 in I. lactea based on proteomics techniques. The study found that IlLTP1 is a cysteine-rich protein, and the expression of IlLTP1 gene was significantly increased by Cd exposure. The heterologous expression of IlLTP1 obviously enhanced Cd tolerance and accumulation in yeast. It is speculated that IlLTP1 may regulate Cd tolerance and accumulation in I. lactea, however, the role of LTP in plant heavy metal tolerance and accumulation is still unclear. In order to clarify the biological function of IlLTP1, the project will focus on the study of the direct (Cd binding and ROS scavenging) and indirect (regulation of GSH synthesis and other pathways) effects of IlLTP1 in regulating Cd tolerance and accumulation in I. lactea. In addition, the effect of IlLTP1 expression level on phytoremediation efficiency of Cd-contaminated soil will be studied. The results will not only enrich the understanding of regulation mechanism of LTP in plant adaptation to Cd stress, but also lay a theoretical foundation for the innovative breeding of new germplasms with the ability to efficiently remediate Cd-contaminated soil.

重金属污染土壤修复对生态环境建设具有重要意义。马蔺是一种Cd积累植物，可应用于Cd污染土壤植物修复，对其Cd耐性和积累机制的研究具有重要价值。申请者前期基于蛋白质组学技术筛选到1个Cd诱导的马蔺非特异脂质转运蛋白IlLTP1。研究发现，IlLTP1为富含半胱氨酸蛋白，Cd能显著促进IlLTP1基因表达，在酵母中表达IlLTP1显著提高其Cd耐性和积累量，推测IlLTP1可能调控马蔺Cd耐性和积累，但LTP在植物重金属耐性和积累中的作用机制尚不清楚。为明确IlLTP1生物学功能，本项目将主要从直接作用（Cd结合和ROS清除）和间接作用（调控GSH合成等途径）两个角度解析IlLTP1调控马蔺Cd耐性和积累的机制，并通过实地修复试验研究IlLTP1表达水平对Cd污染土壤植物修复效率的影响。研究结果不仅可以丰富LTP在植物适应Cd胁迫中的作用机制，也为Cd污染土壤高效修复型植物的培育奠定重要基础。

土壤重金属污染已经成为世界性的环境问题，我国土壤中重金属镉（Cd）污染较为严重，Cd污染土壤的修复和安全利用越来越受到广泛的关注。马蔺是一种鸢尾属多年生观赏植物，具有较强的Cd耐受和积累能力，可应用于Cd污染土壤植物修复，对其Cd耐性和积累机制的研究具有重要价值。本项目首先研究了马蔺幼苗对Cd胁迫的生长和生理响应机制，重点对Cd诱导的马蔺非特异脂质转运蛋白IlLTP1在Cd耐性和积累中的生物学功能进行了全面深入的研究。本项目通过对马蔺IlLTP1蛋白质特征与结构及系统进化分析、Cd处理下马蔺IlLTP1基因表达模式与上游启动子顺式作用元件分析以及转马蔺IlLTP1基因拟南芥在Cd胁迫下的生长表型与生理特性及Cd积累量等相关指标分析，基本阐明了马蔺IlLTP1蛋白在Cd耐性和积累中的作用机制。研究结果表明，马蔺IlLTP1作为一种小分子可溶性蛋白可能主要通过提高植物细胞叶绿素和可溶性蛋白含量、降低细胞膜脂过氧化程度来增强转基因植株Cd耐性，并参与调控Cd在转基因植株不同组织中的积累和分布。本项目研究结果不仅对深入理解非特异脂质转运蛋白在植物适应Cd胁迫中的作用机制具有重要的科学意义，也对Cd污染土壤的治理和农产品的安全生产具有重要的实践意义。