Control of fungal and bacterial diseases of hydroponically cultured tomato plants by 5-fluoroindole and genetic engineering for producing tomato plants resistant to 5-fluoroindole

摘要

Hydroponic culture is one of the recently developed cultivation systems for tomato production in Japan, for easier regulation of growth conditions and for achieving higher yield of high quality tomato fruits. However, this system has an inherent disadvantage that crops are seriously damaged once the medium was contaminated by bacterial or fungal pathogens. In our attempt to find chemicals for controlling soil-borne fungal and bacterial pathogens, we found that 5-fluoroindole (5-FI) was capable of effectively suppressing the growth of a broad range of plant pathogens. The growth of bacterial pathogen, Ralstonia solanacearum was suppressed due to the inhibition of anthranilate synthase (AS), an nitial enzyme in the tryptophan biosynthetic pathway. On the other hand, the fungal pathogens such as Fusarium oxysporum and Verticillium albo-strum were inhibited as the result of inhibition of both the cell wall synthesis and the AS activity. 5-FI is also toxic to tomato plants due to its inhibition of the AS activity. In the present study, therefore, we have cloned a AS gene modified to become resistant to 5-FI from 5-Fl-resistant mutant cells of yeast and used it for transformation of tomato plants.