Benzothiadiazole (BTH)-induced resistance against Botrytis cinerea is inversely correlated with vegetative and generative growth in bean and cucumber, but not in tomato.

摘要

Greenhouse-cultivated tomato, bean and cucumber suffer great economic losses due to grey mould, caused by Botrytis cinerea. Benzothiadiazole (BTH) is a chemical analogue of salicylic acid that induces resistance in a variety of plants by activating the systemic acquired resistance (SAR) pathway. Here, we investigated the effects of foliar applications of different concentrations of BTH on resistance to B. cinerea in these plants and on plant vegetative and generative growth. Leaf treatments with 1 up to 50 mg/l BTH resulted in increased protection of tomato against B. cinerea. However, on bean and cucumber, only concentrations of 250 mg/l and higher, strongly reduced susceptibility against B. cinerea. Moreover, BTH concentrations above 100 mg/l had a significant negative effect on plant height, flower and fruit numbers in bean and cucumber plants under pathogen-free conditions, whereas in tomato only the highest BTH dose (1000 mg/l) resulted in a significant negative effect on vegetative and generative growth. We hypothesize that the protective effects observed on bean and cucumber plants treated with higher levels of BTH are due to a general stress response, which is distinctly different from the BTH-induced resistance observed in tomato at lower concentrations of the compound without negative effects on plant growth.