The Study On Resistance To Water Stress In Tea Plant (Camellia Sinensis)

Tea plant prefers growing under humid environment,but not waterlogging.Water stress becoming one of the important effectors caused huge losses of tea product.The changes of physiological and biochemical indexes,chlorophyll fluorescence parameters and related genes expression level under drought and waterlogging stress were investigated using 'Longjing changye' as material,which employingrapid chlorophyll fluorescence kinetics,quantitative PCR and other techniques.The results are as follow.(1)The changes of superoxide dismutase(SOD)activity,peroxidase(POD)activity,malondialdehyde(MDA),soluble sugar and free proline content were variation under drought stress.As the drought stress level rising,POD,MDA,soluble sugar and free proline were significantly increased,while SOD activity showed a trend of decline after increasing at the beginning.The results indicated that drought stress had significant effect on the growth of tea plant,and these physiological indexes could be employed evaluating the degree of drought stress suffering.(2)The chlorophyll fluorescence parameters of leaves were all affected under drought stress.As the drought stress level rising,?Po??O??Eo?PIABS were gradually reduced,while the ?Do was opposite.The results indicated that Chlorophyll fluorescence parameters,including ?Po??O??Do??Eo?PIABS,were related to the tea plant drought tolerance,which can be used as index of drought resistance in tea plant.(3)The expression levels of five drought-tolerant related genes were performed in the tea leaves under drought stress by quantitative PCR,including 9-cis-epoxy carotenoids dioxygenase(NCED1)phenylalanine ammonia enzyme(PA/L)superoxide dismutase(SOD),catalase(CAT)and delta 1-pyrrole Lin-5-carboxylic acid synthetase(P5CS).The results showed that these 5 genes were induced under drought stress,but the expression patterns were different.Except for NCED1 gene,the relative gene expressions were all increased at certain level.(4)The POD,MDA,soluble sugar and free proline were significantly increased under waterlogging stress,while SOD activity showed a trend of decline after rising at the beginning.The results indicated that waterlogging stress had significant effect on the growth of tea plant,and these physiological indexes could be employed evaluating the degree of waterlogging stress suffering.(5)The chlorophyll fluorescence parameters of leaves were all affected under waterlogging stress.As the treatment time of waterlogging stress increasing,?Po??O??Eo?PIABS were gradually reduced,while the ?Do was opposite.The results indicated that Chlorophyll fluorescence parameters,including ?Po??O??Do??Eo?PIABS,were related to the tea plant waterlogging tolerance,which can be used as index of waterlogging resistance in tea plant.(6)Five related genes in the tea plant were induced under waterlogging stress,but relative expression levels were diverse due to the difference treatment time.Except for PAL gene,the relative gene expressions were all increased at certain level.