Benzothiadiazole Induced Systemic Acquired Resistance In Zuccini To Viruses

Zuccini yellow mosaic virus(ZYMV),Watermelon mosaic virus(WMV)and Cucumber mosaic virus(CMV)are the most important pathogens infecting cucurbitaceous crops. The potential effect of benzothiodiazole to trigger systemic acquired resistance (SAR) in plants against ZYMV, WMV, CMV was investigated by treatment of plants with BTH;With the aid of Semi-quantityitive RT-PCR with the plant's 18SrRNA as internal control, we studied the resistance mechanism too. The results obtained in this study were illustrated as followings:1. Average fresh weigh decreased after treatment of plants with BTH; The better concentration of pre-treatment with BTH to watermelon, melon is 25μg/ml; the better concentration of pre-treatment with BTH to zucchini is 50μg/ml .2. The resistance was evident as a reduced disease severity in BTH-treated plants. Average relative control effect 28 days after treatments reached 55.6%, 56.8% for ZYMV, WMV respectively when pre-treatment of watermelon with 25μg/ml BTH 3 days before virus inoculations; Average relative control effect 28 days after treatments reached 78.2% for CMV when pre-treatment of melon with 25μg/ml BTH 3 days before virus inoculations. The further research indicated that the time between treatment of BTH and the inoculation also affected disease indices; The potential effect of BTH is better than that of Moroxydine hydrochloride copper acetate, K virusicide, Ningnanmycin, Brassinolide.3. Average relative control effect 28 days after treatments reached 39.3%, 45.4%, 87.5% for ZYMV, WMV, CMV respectively when pre-treatment of zucchini with 50μg/ml BTH 3 days before virus inoculations; Average relative control effect 28 days after first treatments also reached 40.6%, 38.7%, 54.8% for ZYMV, WMV, CMV respectively when BTH applied ,1day and 8 days after virus inoculation;Average relative control effect 28 days after treatments reached 38.2%, 42.0%, 54.4% for ZYMV, WMV, CMV respectively when pre-treatment of zucchini with 50μg/ml BTH 3 days before virus inoculations, outdoor cultivation with insect screen 3 days after inoculation.4. The virus concentration of newly developed leaves of plants 28 days after 50μg/ml BTH treatments 3 days before inoculation was analyzed by semi-quantitive RT-PCR with the plant's 18S rRNA as internal control. The results were indicated that 50μg/ml BTH treatment 3 days before inoculation affected WMV, CMV replication but did not affect ZYMV replication.