细胞壁在茶树耐氟中的作用及细胞学机理研究

Tea is a typical polyvinyl fluoride plant, tea leaves contain large amounts of fluoride without poisoning symptoms, so it’s deduced that an important fluoride-resistant mechanism exists in tea, It’s popular in the current study to research fluoride-resistant and fluorine-detoxification mechanisms in tea, previous studies mainly focused on fluoride-aluminum complex detoxification, relationship between root secretion of organic acids and fluoride, accumulation characteristics and physiological feature of fluoride to investigate the mechanism of fluoride-resistant, while the real reasons haven’t been found out. The applicant found that 60 percent of fluorine located in the tea leaves cell wall and pectin, one of the cell wall components, responded to fluorine, aluminum, calcium, and their interactive processing in their previous studies. Therefore, cell wall plays an important role in fluorine resistance in tea. This paper intended to study the relationship of fluoride and the cell walls, mainly investigated polysaccharide of cell wall, cell wall structure in the role of tea fluoride-resistant, and fluoride distribution and chemical existence in the cell wall components, aimed to clarify the role of cell walls in the tea fluoride-resistant and cytological mechanisms, to provide theoretical and experimental evidence of tea fluoride-resistant mechanism, also had an important theoretical significance of cultivar selection of low fluoride tea.

茶树是一种典型的聚氟植物，茶园茶树叶片中含有大量的氟但却未出现中毒症状，因此茶树中存在着重要的耐氟机制，目前茶树中耐氟及氟解毒机制研究已成为茶树氟研究的热点，前人的研究多集中在氟铝络合解毒、根系有机酸分泌与氟的关系、氟的累积特性、生理等方面探讨耐氟的机理，但仍没有找到耐氟的真正原因，申请人在前期的研究中发现，60%的氟定位在茶树叶片中细胞壁上，并且细胞壁组分之一果胶对氟、铝、钙及交互处理做出了响应，因此，细胞壁在茶树耐氟中起着重要作用，本课题拟从氟与细胞壁的关系入手，研究细胞壁多糖组分、细胞壁结构在茶树耐氟中的作用及氟在细胞壁组分中的分布及赋存形态，来阐明细胞壁在茶树耐氟中的作用及细胞学机理，为探明茶树耐氟机制提供理论与实验依据，对茶树低氟品种的选育也具有重要的理论意义。

茶树是一种聚氟植物，体内聚集着大量的氟，但未见茶树出现中毒症状，说明茶树体内存着耐氟机制，经过前期研究发现，细胞壁在茶树耐氟方面起着关键性作用。本项目以高氟品种和低氟品种两个茶树基因型为材料，重点围绕氟与细胞壁多糖组分的关系、氟在细胞壁组分中的分布、氟在细胞壁的结合位点及氟、细胞壁、金属元素之间的关系进行了研究。结果表明：（1）不管是氟铝单独还是氟铝交互处理，增施钙后对细胞结构破坏程度明显减轻，且增施钙后改变了细胞壁的组分（果胶含量）及结构，抑制了茶树对氟的吸收；（2）经细胞壁多糖组分分离测氟发现，不管是高氟品种还是低氟品种，氟主要聚集在细胞壁果胶中；并随着水培中氟浓度的增加，细胞壁多糖组分中的糖醛酸和总糖含量均显著升高；（4）通过改性研究及改性前后细胞壁对氟的吸附研究发现，氟主要结合在细胞壁中的羧基、氨基和果胶质，并与Al、Mg、Mn、Cu、Fe 、K等金属元素关系密切；（5）通过细胞壁、氟及金属元素络合研究发现，在高氟品种氟与Ca、Mg、K、Mn关系密切，在低氟品种中，氟与Al、Mg关系较为密切；（6）茶树体内抗氧化系统和抗坏血酸-谷胱甘肽循环系统在茶树耐氟方面也起着重要作用，抗氧化系统和抗坏血酸-谷胱甘肽循环系统中的保护性酶及抗氧化物质在一定范围内能及时清除ROS，保护茶树免受氟伤害。