Effects Of Exogenous Hydrogen Sulfide On The Salt Tolerence Of Tea Plant

Tea plant?Camellia sinenisis?is a kind of plant that is oxyphilous and thermophilic but sensitive to cold and salt-alkali,hence easily affected by heat,chilling,drought,salinity and so on.The soil salinization as a global environmental problem,not only cut down the agricultural acreage,reduced crop yield and quality in some areas of China,but also had a serious impact on the development of tea industry and tea production and quality in saline alkali area of our country.Hydrogen sulfide as an important signaling molecule that plays an important role in enhancing plant response ablity to abiotic stress,many studies have found that hydrogen sulfide can improve plant salt tolerance through participating in the regulation of antioxidant system,redox homeostasis and ion balance.In this study,by the method of pot experiments with the mixture of river sind and turf substrate?1:1,V/V?,the biennial cutting seedlings of tea cultivar 'Pingyangtezao' were choosed as test materials,from which those seedlings with the same growth were selected and divided into two groups?each group of 12 pots?for further treatment.In the first group,seedlings were cultivated in the pots with 400 mL solution of 100 mmol·L-1NaCl;while in the second group,seedlings were treated with the same dosage of water as the control.After 10 days,the different concentrations of NaHS?0,0.05,0.1,0.5 mmol·L-1?were prepared for foliage-spray treatments.The seedlings in two groups were sprayed once every 3 days for 3 times.After 3 days of the last spraying,various physiological parameters were determined.By treatments with different concentrations of NaHS?0,0.05,0.1,0.5 mmol·L-1?which is a donor of H₂ S,leaf mass per area?LMA?,root activity,the activities of antioxidant enzymes,the level of antioxidants,reactive oxygen species?ROS?and lipid peroxidation of tea plant were determined to expand the application of exogenous hydrogen sulfide?H₂S?in the salt resistance of tea plant.The results are as follows:1.Under salt stress,chlorophyll content and LMA were significantly reduced,which would severely affect the photosynthesis of the tea plant,while the adverse impact was eased by exogenous H₂ S through increasing chlorophyll content and promoting the accumulation of dry matter;root activity was also significantly inhibited by salt stress,while exogenous H₂ S could alleviate the damage induced by salt stress and enhance root activity of tea plant.2.Exogenous H₂ S could regulate cell osmotic potential and maintain the stability of cells and the protein structure through increasing content of free proline?Pro?and soluble proteins.3.Salt stress led to the excess accumulation of hydrogen peroxide?H₂O2?,superoxide?O2-?and malondialdehyde?MDA?,and increaed electrolyte leakage of leaves which would seriously affect the structure and function of cell membrane;exogenous H₂ S could reduce the generation of reactive oxygen species?ROS?and the degree of membrane lipid peroxidation,maintain membrane stability and redox homeostasis of tea plant under salt stress by enhancing the activities of antioxidant enzymes,including superoxide dismutase?SOD?,catalase?CAT?,peroxidase?POD?,ascorbate peroxidase?APX?and glutathione reductase?GR?,and the content of non-enzymatic compounds such as ascorbate?AsA?and glutathione?GSH?,thus reducing NaCl-induced oxidative stress.4.Exogenous H₂ S could improve the adaptability of tea plant to salt stress.The optimum treatment concentration of NaHS was 0.1 mmol·L-1.