红树植物白骨壤碳同化途径对高盐环境的响应

Mangrove is a vegetative group which distributed along tropical and subtropical coastal tidal zone. The carbon assimilation pathway of mangrove plants was considered as C3 type under natural habitat salinity. However, under high salinity, some phenotypic characteristics are much similar with CAM plants at several aspects. It is not clear yet whether the transition of carbon assimilation pathway from C3 to C4, CAM or their intermidates happened or not. In this program, we will comprehensively analyze the effects of high salinity on carbon assimilation pathway transition at ecological, morphological and anatomical, physiological, biochemical and molecular levels by employing Avicennia marina, a typical mangrove plant as experimental material. The study mainly includes the effects of high salinity on: (1) leaf carbon stable isotopic value (δ13C), (2) leaf succulence, Kranz structure and ultramicroscopic features of chloroplast, (3) gas exchange characteristics and photosynthetic parameters, (4) transcript and protein abundance of photosynthesis-related enzymes and its activities, particularly the ratio of PEPCase/RuBPCase, (5) day and night variations of organic acid contents, (6) changes of differentially expressed proteins and genes and the regulation networks related to photosynthesis. The objective of this program is to elucidate the possibility and mechanism of transition of carbon assimilation pathway from C3 to C4, CAM or their intermidates type in mangrove plant A. marina under high salinity condition. The results and conclusions will be important and have high scientific significance to understand the salt tolerance mechanism of mangrove plant, and have application values in ecological restoration of mangrove forest.

红树林是一类生长于热带亚热带潮间带的盐生植物类群，在正常生境盐度下其碳同化途径被认为是C3途径，在高盐下，其表型与CAM植物有许多类似的特点，但其碳同化途径是否向C4特别是CAM或中间类型转变仍不清楚。本课题以典型红树植物白骨壤为实验材料，从生态、形态解剖、生理、生化和分子水平综合分析高盐对叶片碳同化途径转变的影响。主要内容包括研究高盐对白骨壤叶片：(1)碳稳定同位素值（δ13C）；(2)叶片肉质化程度、花环结构、叶绿体超显微结构特征；(3)气体交换特征与光合参数；(4)光合酶基因、蛋白表达水平、活性及PEPCase/RuBPCase比值；(5)有机酸含量昼夜变化；(6)差异表达蛋白和基因谱变化及与光合相关调控网络的影响。阐明高盐对红树植物白骨壤叶片碳同化由C3向C4、CAM或中间类型转变的可能性及机制。结果对深入理解红树植物的耐盐机理具有重要的科学意义，对红树林生态恢复也有应用价值。

红树林是一类生长于热带亚热带潮间带的盐生植物类群，在正常生境下其碳代谢途径被认为是C3途径，在高盐下，其碳代谢途径是否向C4特别是CAM或中间类型转变仍不清楚。本课题以典型红树植物白骨壤为实验材料，从生态、形态解剖、生理、生化和分子水平综合分析高盐对叶片碳代谢途径转变的影响。主要内容包括研究高盐对白骨壤叶片：(1)碳稳定同位素比值（δ13C）；(2)花环结构、叶绿体超显微结构特征；(3)气体交换特征与光合参数；(4)光合酶基因、蛋白表达水平、活性及PEPCase/RuBPCase比值；(5)有机酸含量昼夜变化；(6)与光合相关蛋白和基因表达的影响。阐明了高盐对红树植物白骨壤叶片碳代谢由C3向C4转变的可能机制。结果对深入理解红树植物的耐盐机制具有重要的科学意义，对红树林生态恢复也有应用价值。