长时间高光胁迫下光敏型茶树突变体叶绿体适应性分子机制

TTo chlorina or albino tea plant cultivar sensitive to high-light stress, and achieve the target of characteristic tea industry in Guangdong, a number of chlorina or albino tea plant cultivars with excellent quality had breed and been planted in a small scale. Investigation of field adaptation showed that sunburn or sunburn spots on the leaves appeared of chlorina or albino tea plant cultivars under long-term high-light stress, while new bred shoots manifested the strong ability to endure strong light. This phenomenon may be related with chloroplast adaptability in response to long-term high light stress. .The project will aim to reveal photoprotection mechanism within the chloroplast in response to long-term high-light stress, of photo-sensitive tea plants (YHong91 and YHong92) and normal type YHong9 as the experimental materials. The photoprotection mechanism will involve in non photochemical quenching mechanism, the changes of xanthophyll cycle and catechins including related gene expression. The alteration in the organization of the photosystem will be explored due to the changes of thylakoid membrane protein and subcomponents, even its related gene expression. The collaborative relationships between photoprotective mechanisms and photosystem components or subcomponents will be discussed for the chloroplast in response to long-term high-light stress. This project has solid foundation and unique experimental materials. The study will lead to a practical significance to the selection and promotion of chlorina or albino tea plant cultivars.

针对新梢为白色或黄色的珍稀茶树品种（系）不耐强光的缺点，以及广东建设特色茶产业的目标，申请人多年来筛选出一些加工品质优异、新梢叶色表现稳定的白色或黄色的茶树新品系并有少量应用。田间适应性调查表明，在长时、高光下未成熟叶常常出现晒斑、日灼斑等问题，但其萌发新梢表现出极强的耐强光能力，该现象可能与叶绿体对长时间高光胁迫的适应性有关。.本项目拟以光敏型突变体YHong91（新梢为白色）、YHong92（新梢为黄色）和正常型YHong9为实验材料，揭示其叶绿体内的光保护响应机制（非光化学淬灭机制、叶黄素循环和儿茶素组分及其相关基因表达）和光系统蛋白响应特点（类囊体膜蛋白组成和亚组分及相关基因表达），并探讨长时间高光胁迫下叶绿体内光保护响应机制与光系统蛋白组成或亚组分间的协作关系。本项目前期研究基础扎实，实验材料独特，对新梢白色或黄色茶树品种（系）选育和应用具有实际意义。

新梢为白色或黄色的珍稀茶树品种在长时、高光下未成熟叶会出现晒斑、日灼斑等问题，但其萌发的新梢确表现出极强的耐强光能力，该现象可能与叶绿体对高光胁迫新梢为白色或黄色的珍稀茶树品种在长时、高光下未成熟叶会出现晒斑、日灼斑等问题，但其萌发的新梢确表现出极强的耐强光能力，该现象可能与叶绿体对高光胁迫的适应性有关。针对这一问题开展以下研究，主要结果为：（1）高光胁迫下，突变体YHong 91、YHong 92和正常型YHong 9光合响应不同，YHong 92和YHong 9光合响应接近，更多研究结果还在进一步分析中。（2）高光胁迫下， YHong 91中酯型儿茶素组分和黄酮类含量显著增加，非酯型儿茶素组分降低，黄酮和黄酮醇合成途径基因表达下调。YHong 92和YHong 9中儿茶素组分含量差异不显著，花青素和黄酮醇类代谢物含量显著增加，与黄酮醇类代谢途径相关基因表达上调。高光胁迫下，YHong 91、YHong 92和YHong 9中叶绿素a和b含量降低。YHong 91中玉米黄素含量显著增加。YHong 92和YHong 9中类胡萝卜素含量增加。（3）高光胁迫下叶绿体光系统Ⅱ蛋白、光系统Ⅰ蛋白、叶绿素 a-b 结合蛋白、c细胞色素 b6和细胞色素 f等光合膜蛋白含量均降低，其编码基因PsbC、PsbA、PsaC、Lhca3、PetB和PetA等表达水平有所差异。本项目初步揭示了茶树YHong 91、YHong 92和YHong 9在高光胁迫下的光保护响应机制和叶绿体光系统蛋白响应差异，对进一步明晰茶树次生代谢产物黄酮类、花青素和儿茶素组分光保护响应机制，系统探明叶绿素与光系统蛋白响应光胁迫机制具有启发性意义。