| The Chinese Cymbidium is a rare plant with ornamental and scientific research values.Cymbidium tongibracteatum is the variant of Cymbidium goeringii and it widely distributed in Chinese.Also it cultivation has a long history and widely loved by people. It is one of the Cymbidium goeringii five golden flowers and iongchangsu’has big flowers, smell good, beautiful attitude, look elegant,plain color and pure feeling. It has won many awards both at home and abroad with great economic value.The leaf color mutant exist extensively in plants.The type of it is very rich also with high frequency,wide source, formation mechanism is also different. The leaf color mutant, which is an ideal material, has been used on the study of photosynthesis, chloroplast development, hormone, chlorophyll metabolism and some physiological metabolic processes. It also plays a key role in the research of the genetic and breeding.This experiment mainly used Chinese orchid cymbidium longchangsu in the leaf color mutant and wild type as the contrast material. study on the two material in the physiological and biochemical, photosynthetic characteristics and molecular level differences.The key results include:1. The photosynthetic pigment comment of the mutant is lower than the wild type control, The chlorophyll a and chlorophyll b content of mutant decreased to 16.71% and 15.88% respectively. The total chlorophyll content was 20.71% of the control, indicating a serious lack of Xantha mutant of chlorophyll.2. Light parameters indicate that Xantha has higher stomatal conductance, net photosynthetic rate, transpiration rate, and intercellular CO2 concentration was lower than that of the control; The chlorophyll fluorescence kinetics analysis showed that the mutant apparent quantumefficiency and carboxylation efficiency is higher,with stronger PS Ⅱ activity, light harvesting efficiency, conversion efficiency and the actual photochemical quantum yield are higher; CO2 saturation point and compensation point was lower; light response curve shows that the mutants in the case of lack of intensity,photosynthetic rate is lower, but both CK and mutant have good tolerance to strong light. Indicate.3. Chloroplast ultrastructure show that there is a big difference about the chloroplast shape between two material.The wild type nucleus is located in the corner of cell, clearly visible, the chloroplast of mutant is roughly oval, number, shape and clear, Mutant chloroplasts has irregular shape, no developed thylakoid,both can be observed in mitochondria, starch grains and other organelles in the cytoplasm. Chloroplast and starch grains were squeezed into the cell edge, is along the oval shaped cells distributed uniformly.4. During its growth process, the wild type and the mutant rate of the relative conductivity and MDA content are increased.Both of the growth rate of the relative conductivity are the same. Mutant MDA growth is bigger than the wild type control,the soluble sugar content of mutant was lower than that of the control. Free radicals and reactive oxygen species can not be cleared by increase of SOD and POD activity of protective enzyme.And the plant cell membrance of leaf color mutant get hurt more.5. SRAP molecular markers showed that:the DNA of wild type and mutant was amplified using different primers, significant differences with rich polymorphism, clear bands, and 8 pairs of primer samplified 272 bands, the each pair of primers amplified 17 bands in average; about 8 primer combinations of wild type and mutant, the number of amplified bands are not consistent, can be amplified 24 bands.Initially speculated that the leaf color mutant DNA changed. |
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