Resistance to tomato yellow leaf curl virus in tomato induced by benzothiadiazole

The resistance to tomato yellow leaf curl virus(TYLCV) induced by benzothiadiazole was detected on resistant tomatoes 1479 and 2300,and the activities of several defense enzymes of tomato after benzothiadiazole spraying or TYLCV inoculation were determined as well.0.1-2.0 mmol/L benzothiadiazole showed an induction of TYLCV resistance,and 0.5 mmol/L benzothiadiazole displayed the best effect with induction efficiency of 42.7%.The defense enzymes in tomato seedlings such as superoxide dismutase(SOD),peroxidase(POD),polyphenol oxidase(PPO) and phenylalanine amonnialyase(PAL) all increased after benzothiadiazole spraying or TYLCV inoculation,and their activities in tomato treated by both spraying benzothiadiazole and TYLCV inoculation rose faster than those treated by benzothiadiazole spraying only.It indicated that spraying benzothiadiazole on tomato could enhance the activities of defense enzymes,and reduce the disease index significantly,resulting in increase of TYLCV resistance.