Regulation Of Exogenous NO And Sucrose To Tomato Physiological Characteristics And Resistance Genes Under Salt Stress

Mainly by using pot culture methodology and started with the systematic analysis of plant biology and physiological responses on salt stress, studies on regulation of different concentrations of exogenous nitric oxide and sucrose to tomato seedlings resistance genes and physiological characteristics were carried out in present thesis, including mechanism of plant salt resistance under salt stress, regulation effects of exogenous nitric oxide and sucrose induced expressing their preexistent genetic information for tolerance under salt stress in seedlings. The major results are presented as follows:1. Under 100 mmol/L NaCl stress condition, the different concentrations at 0.1, 0.5 and 1.0 mmol/L SNP could alleviation of NaCl stress damage and increase activities of antioxidant enzymes (including SOD, CAT, POD and APX) in leaves, the best effect was observed in the treatment of 0.1 mmol/L SNP. The same dosage effect of sucrose existed on the alleviation of NaCl stress in tomato seedlings were observed, 3.0 mmol/L increase activities of antioxidant enzymes at 24 h significantly, with the tolerance time, the activities of antioxidant enzymes were decreased.2. Germination of tomato seed is reduced at relatively low NaCl concentrations and lengthening the time needed to complete germination. During the germination process in tomato, Applying the 0.1 mmol/L SNP, 1.0 mmol/Lsucrose and the mix-solution of SNP and sucrose increased the seed germination rate,germination potential,germination index and activity index of tomato, the mix solution of SNP and sucrose could largely promote germination rate, which was 81.67%, the germination rate was 56.67% under single salt stress.3. The results indicated that there were protective function to tomato seedling leaves from NaCl oxidative damage when applications of SNP, sucrose and their mix solutions. However, their mix solutions showed a much better protective impact than the treatments of SNP and sucrose as it could significantly increase activities of antioxidant enzymes and content of proline,while largely decrease MDA content in tomato seedling leaves under salt stress. Moreover, the effect of salt stress on the peroxidase enzyme expression in tomato leaves was further analyzed by using polyacrylamide concentration gradient gel electrophoresis technique. The results showed that salt stress could inhibit the expression of small molecule POD isoenzymes. The mix of SNP and sucrose could largely promote POD isoenzyme activity and protective them from hydrolyzation than single application of either SNP or sucrose solutions. Irrespective of solution, the POD isoenzymes expression was higher at 24 h than 48 h salt stress. The mix solution of SNP and sucrose could have a big potential for reduction of oxidative damage to tomato seedling leaves under salt stress. 4. The resistance gene NP24 and PR-5 expression were assayed by QRT-PCR at mRNA level in tomato plants treated with SNP, sucrose and the mix solution of SNP under salt stress. They could induce NP24 gene expression at 12 h. compared to single stress, NP24 gene relative expression level increased respectively 38.44﹪,24.48﹪and 74.51﹪.There has the maximum expression of PR-5 under single salt stress at 12 h, the expression level decreased along with the time extending. Compared to single salt stress, PR-5 gene relative expression level increased respectively 46.53﹪, 43.20﹪and 65.02﹪. It was suggested that the mix solution of SNP and sucrose treatment induced the strong expression of NP24 and PR-5.