The Chlorophyll Biosynthesi Of Chlorophytum Capense Var. Medio-pictum And Its Responses To High Light Stress

Chlorophyll is a kind of tetrapyrrole molecules in plants, and it can act as a kind of photosynthesis pigment in the photosynthesis, which can transfer electron to the photosynthetic reaction center by capturing light energy. In photosynthetic organism, chlorophyll metabolism is a highly coordinate process that consists of a series of catalytic reactions. Chlorophytum capense var. Medio-pictum is a horticultural cultivar variety of Chlorphytu. Capense (L.) Kuntze, which belongs to Liliceae. It is a kind of perennial plant. The center zone of leaf is yellow and the edge is green, which form a green-yellow-green stripe. In this paper, Chlorophytum capense var. Medio-pictum was applied to analyze the flow of chlorophyll metabolism. Simultaneously, we also studied the level of D1 and D2 protein in PS II and the structure of leaf epidermis. In addition, physiological responses to high light stress in the centre and edge parts of Chlorophytum capense var. medio-pictum were investigated. The main research results are as follows:1. Using the methods of the fluorescence spectrophotometer and ultraviolet visible light spectrophotometer, the flow of chlorophyll metabolism were analyzed, the results showed that there were three inhibited sites in the flow of chlorophyll metabolism in the center of Chlorophytum capense var. medio-pictum:ALA, Proto IX and Pchlide. The first intermediate in tetrapyrrole biosynthesis, ALA, in the center of Chlorophytum capense var. medio-pictum was obviously lower than that in the other parts. Therefore, the forming of yellow stripes in Chlorophytum capense var. medio-pictum might be due to that the biosynthesis of ALA was inhibited.2. Using the method of SDS-PAGE and Western blot, we analyzed the total protein content, the content of chloroplast protein and the level of core protein D1 and D2 in the center and the edge of Chlorophytum capense var. Medio-pictum. The results showed that the contents of the total protein and chloroplast protein in the central part were significantly lower than other parts, and there was only trace amounts of D1 protein in the golden zone of the leaf.3. Using the method of phytotomy and phytochemistry to analyze the epidermal cells and stoma in the central part of Chlorophytum apense var. medio-pictum were obviously larger than that in the other parts; but cell density and stomatal density were significantly lower.Compared with Chlorophytum capense, the shape of root tuber was more slender in Chlorophytum apense var. medio-pictum, and the number of fibrous roots increased. Simultaneously, the content of total polyphenol in the root tuber was significantly lower than that in Chlorophytum capense.4. Under the condition of normal light, PSII activity of yellow stripe was lower than that of green stripe and green leaf of Chlorophytum capense. However, reactive oxygen species was on the high level, and photosynthetic parameters of yellow stripe was on low level; In 6 hours of high light stress, the level of reactive oxygen and activity of antioxidant enzymes varied relatively smoothly in yellow stripe; under a few minutes high light stress, non-photochemical quenching increased in all tissues, but the non-photochemical quenching of the yellow stripe increased less than the others. These results demonstrated that excess light energy in the yellow-stripe tissue was not dissipated in the form of heat; furthermore, the level of non-photochemical quenching in the yellow stripe could restore in a few minutes in low light.