Interactions Between Race 2 of Fusarium oxysporum f. sp. Lycopersici and Near‐Isogenic Resistant and Susceptible Lines of Intact Plants or Callus of Tomato 58731 F71 137

Abstract

Abstract The interaction between Fusarium oxysporum f. sp. lycopersici race 2 and near‐isogenic resistant and susceptible tomato lines of the cultivar Moneymaker and callus cultures derived from these lines was studied. Resistance was expressed in callus tissue for a short period, during 4 days after inoculation. This was shown by a delay in fungal growth on callus tissue derived from resistant plants. Accumulation of the phytoalexin rishitin was similar in callus tissue and whole plants. Tomato plants resistant to race 2 did not accumulate more rishitin than susceptible plants during the first 4 days after inoculation, in contrast to plants resistant to race 1 and inoculated with race 1. The different response of tomato plants and calli towards race 1 and 2 of F. oxysporum f. sp. lycopersici suggests that the mechanism of resistance controlled by the 1–1 and the 1–2 gene is different. Callus tissue might be useful to study these differences in resistance.