Effects of BTH on TYLCV resistance,photosynthetic characteristics and related defense enzymes of tomato seedlings

In this study,the effect of benzothiadiazole(BTH)on induced resistance to Tomato yellow leaf curl virus(TYLCV)in tomato was investigated.TYLCV resistance,photosynthetic characteristics and the activities of several defense enzymes were measured in tomato leaves after being treated with BTH.The results showed that 0.10-2.00 mmol·L-1 BTH had different effects on induced resistance,and 0.50 mmol·L-1 BTH had the best effects on tomato seedlings so that the induced efficiency of resistance reached 42.7%.Net photosynthetic rates(Pn)and stomata conductance(Gs)increased significantly after treatment with BTH,and BTH could slow down the decreasing of Pn and Gs after being inoculated with TYLCV.The defense enzymes of tomato seedlings such as peroxidase(POD),polyphenol oxidase(PPO)and phenylalanine amonnialyase(PAL)increased after BTH inducement or TYLCV inoculation.These enzymes treated with both BTH inducement and TYLCV inoculation increased more rapidly than those only treated with BTH inducement.In conclusion,the results indicated that BTH can alleviate the damage on photosynthesis by TYLCV,enhance the activities of defense enzymes,and decrease disease index significantly so as to increase tomato resistance to TYLCV.