Epistatic influence in tomato Ve1-mediated resistance   
C. CASTROVERDE (1), R. Nazar (1), J. Robb (1) (1) Molecular and Cellular Biology, University of Guelph, Canada

Verticillium wilt resistance has been associated with the Ve gene family comprising two genes, Ve1 and Ve2, encoding putative receptor-like proteins. There is current debate about the individual roles of Ve1 and Ve2 in tomato and other host plants. As an initial step to in planta mutagenic analyses of Ve function, the Craigella Resistant (CR) tomato Ve1 and Ve2 alleles were separately overexpressed in Craigella Susceptible (CS) plants. Stable transgenics were evaluated in terms of plant architecture, Ve expression levels, transgene copy number and resistance to Verticillium dahliae race 1 (Vd1). 35S:Ve1 plants divided into two distinct classes; about half exhibited CR-like fungal levels and symptoms and half resembled CS tomatoes. Expression analysis revealed that Ve1 transcript levels were higher than in non-transformed plants, showing successful and stable Ve1 overexpression. Ve2 transcript levels were similar between 35S:Ve1 and non-transformed plants, demonstrating that the Ve1 transgene does not significantly affect endogenous Ve2 expression. These observations were consistent in several biological experiments and in all transgenic lines tested. On the other hand, 35S:Ve2 plants had comparable fungal levels and symptoms to CS tomatoes. Since CS plants possess the full-length Ve2 protein, this indicates that additional Ve2 copies do not have any noticeable effects on the resistance response. The Ve2 transgene also did not influence Ve1 mRNA levels. Altogether, these results confirm the role of Ve1 in Vd1 resistance but suggest the influence of a yet undefined factor.

Abstract Number: P17-503
Session Type: Poster