Abstract

Foliar spray of validamycin A (VMA) controls tomato wilt caused by Fusarium oxysporum f. sp. lycopersici, and induces salicylic acid (SA)-mediated systemic acquired resistance (SAR) in tomato.1) NahG-tomato (Z617; Sainsbury Laboratory, UK) is a transformant of cv. Moneymaker expressing bacterial salicylate hydroxylase gene (nahG). 2) Accumulation of SA and establishment of SAR are prevented in NahG-tomato. 2) We found that foliar spray of VMA (50 μg/ml) generated severe chemical injuries, such as necrosis on petioles, in NahG-tomato which were not observed in cv. Monaymaker. This may be due to the excess accumulation of catechol catalyzed from SA by NahG in NahG-tomato tissues. Possibility of screening SAR-inducers using chemical injury on NahG-tomato as an indicator was revealed. Moreover, foliar spray of VMA (10 μg/ml) on NahG-tomato controlled wilt as well as on cv. Moneymaker depending on the conditions, suggesting that the mode of action of VMA against Fusarium wilt was not only SAR.
1) Ishikawa et al, Phytopathology 95, 1209 (2005); 2) Brading et al, Plant J. 23, 305 (2000).

*Sumitomo Chemical Co.
**RIKEN