Study On Responses Of Physiological And Related Gene Expression To Drought Stress And Re-watering In 'Red Sun' Kiwifruit Seedlings

Fruit trees are often faced of drought stress in Southwest China during the process of growth and development, and the drought period is the time of Vigorous growth, weak of drought-resistant ability, large water requirement growth period kiwifruit. The southwest region in Southeast Sichuan and Chongqing is drought disaster prone and heavy disaster areas, with the characteristics of the high frequency, large area suffered. In recent years due to global warming, drought disaster is aggravating trend in summer.'Red sun' kiwifruit (Actininia chinensis cv.Red sun) varieties of seedlings were used as experimental materials in this experiment, and controlling water to drought stress and normal water supply as control, samples were taken to measure the changes in physiological and molecular mechanism during the period of drought stress and re-watering. Finally, the data analysis software was used to analyze the changes of physiological indexes and the changes of the expression levels of several genes related to drought stress in order to provide a theoretical basis for the cultivation and resistance evaluation of kiwi fruit in future.The main results obtained are as follows:1.Under drought stress, chlorophyll was degraded in 'Red sun' kiwifruit seedlings leaves, increased in relative conductivity, MDA content, soluble sugar, soluble protein proline and so on, penetration regulating substances accumulated in the body, accumulated to a certain period of time fallen, the activity of root and activity of antioxidant enzymes showed a trend toward that increased first and then decreased, indicating that the drought resistance have a certain threshold, when the dress reached a certain stage, plants tissues and cells would be severely damaged.2.Re-watering after stress had a certain effect on improving the growth of 'Red sun' kiwifruit seedlings, but the effect was determined by the period of re-watering, if the rehydration time was too late, it would cause irreversible damage, even after rehydration would not make it back the original states.3.Photosynthetic characteristics of 'Red sun' kiwifruit seedlings was damaged under drought stress:intercellular carbon dioxide concentration had been in a rising trend, while the transpiration rate of leaves falling, and net photosynthetic rate and stomatal conductance showed a trend that increasing at first and then fallen. The PS ? photochemical quantum yield began to decline from the ninth day of stress which showed a slight compensation effect under drought stress. while the stress follows caused that the photosynthetic capacity of plant leaves decreased continuously.4.The results of Relative Quantification Real-time PCR about drought resisting related genes, which showed that drought stress could induce the expression of genes drought stress related in 'Red sun' kiwifruit seedlings. But the levels of expression were different. The results showed that, as the key gene, P5CS, in the metabolic pathway of proline, its expression are higher than other genes.