Cf Gene-Dependent Induction of a ß-1,3-Glucanase Promoter in Tomato Plants Infected with Cladosporium fulvum . Tom Ashfleld. Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich, NR4 7UH U.K. Kim E. Hammond-Kosack, Kate Harrison and Jonathan D.G. Jones. Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich, NR4 7UH U.K. MPMI 7:645-656. Accepted 6 June 1994. Copyright 1994 The American Phytopathological Society.

Tomato Cf genes confer resistance to specific races of the leaf mold pathogen Cladosporium fulvum. The Cf gene-dependent induction of a Nicotiana plumbaginifolia ß-1,3-glucanase (gnl) promoter -GUS reporter gene fusion was monitored following either inoculation with race 0 C. fulvum or leaf injections with race-specific elicitors. In incompatible interactions, intense foci of GUS activity appeared at infection sites 1-4 days after hyphae entered the leaf through stomata. The time of appearance of these foci and their relative final size was different on Cf-2, Cf-4, Cf-5, or Cf-9-containing near-isogenic lines (NILs) of the cultivar Moneymaker. In the compatible interaction, gnl:GUS induction was later and occurred just prior to sporulation. Co-localization of GUS activity and fungal hypliae revealed that the spatial patterns of induction in relation to fungal hyphae differed between the various incompatible interactions studied. Following race-specific elicitor injection, increased GUS activity was only detected in Cfgene-containing NILs. Induction was detected in the Cf-9 containing NIL within 12 hr and in those carrying Cf-2 or Cf-5 within 24 hr. RNA gel blot analysis showed that the induction kinetics of the gnl promoter resembled that of an endogenous acidic ß-l,3-glucanase gene.