Physiological Mechanism Of Tomato Resistence To Tylcv Induced By Riboflavin

In order to investigate the induced resistance effect and mechanism of riboflavin to tomato yellow leaf curl virus (TYLCV), tomato cultivar’1479’were treated with2.0mmol-L-1riboflavin and TYLCV inoculation, the defense enzymes varieties, antioxidant system and secondary metabolites were studied. The main purpose of this test is to provide theoretical basis and practical experience for tomato yellow leaf curl virus disease control. The results are as follows:1. Riboflavin can significantly lower disease index of tomato yellow leaf curl virus, and the induced resistant effect of2.0mmol-L"1riboflavin was the best, reached41.91%. After TYLCV inoculation, plant height, stem diameter, the dry and fresh weight of leaves decreased markedly, when compared to the control. Growths of tomato plants to be restored and biomass increased significantly after spraying2.0mmol-L-1riboflavin. Meanwhile, soluble protein and chlorophyll contents massive accumulated.2. The activities of PPO, PAL, CHT and GLU were increased significantly in tomato leaves within96h after spraying2.0mmol-L"1riboflavin. After inoculating TYLCV, the activities of defense enzymes in tomato leaves were further significantly increased after inducing by the riboflavin. The activities of PPO, PAL, CHT and GLU in plants inoculated with TYLCV were higher than those of un-inoculated plants. The above results indicated that the systematically-enhanced activities of the defense enzymes by riboflavin were closely correlated to the induced resistance of tomato to TYLCV, which may belong to the metabolism of systemic acquired resistance.3. The histochemical localization of H2O2showed that2.0mmol-L-1riboflavin and TYLCV inoculation treatment have contributed to the accumulation of H2O2content. The activities of SOD, POD, CAT and APX were increased significantly in tomato leaves within96h after spraying riboflavin.The MDA content, the O2·-production rate and the H2O2content increased. The POD, CAT and APX activities increased while the SOD activities decreased. Riboflavin significantly decreased MDA and H2O2contents and O2·-production rate and increased SOD, POD, CAT, APX activities of tomato leaves under TYLCV inoculation.This indicated that riboflavin could reduce reactive oxygen species production and raise the activities of antioxidative enzymes, decrease the membrane lipid peroxidation in tomato seedlings after inoculating TYLCV, alleviate the damage of TYLCV to the plants.4. The content of total phenols and flavonoid were increased significantly in tomato leaves within96h after spraying2.0mmol·L-1riboflavin. After inoculation, the content of total phenols and flavonoid in tomato seeding leaves increased rior to decrease, leading to peak at15d. While, the lignin contents increased all the time. Riboflavin increased significantly the contents of three secondary metabolites in tomato leaves after inoculating TYLCV. This indicated that riboflavin could improve secondary metabolites production, which is closely correlated to the induced resistance of tomato to TYLCV.