Title : Wounding induces tomato Ve1 R-gene expression
Abstract:
In tomato, Verticillium resistance is determined by the Ve-gene locus, which encodes two leucine-rich repeat-receptorlike proteins (Ve1, Ve2). The gene encoding Ve1 protein has two functional alleles; Ve1, encoding a resistance protein, and ve1, with a premature stop codon encoding a truncated product. In both resistant and susceptible plants, Ve1 is induced differentially while Ve2 is constitutively expressed throughout disease development. Contrary to their putative role in Verticillium resistance, these profiles have been observed even during compatible Verticillium interactions, colonization by some bacterial pathogens, and growth of transgenic tomato expressing the fungal Ave1 effector, suggesting broader roles in disease and/or stress. Here we have examined further Ve-gene expression in resistant and susceptible plants under abiotic stress, including drought, salinity and physical damage. Using qRT-PCR and label-free LC-MS methods, changes have been evaluated at both the mRNA and protein levels. The results indicate that Ve1-gene expression responds specifically to physical damage or plant wounding, resulting in a defense/stress cascade that resembles observations during Verticillium colonization. In addition, changes in Ve1 or Ve2 function also result in responses that occur with wilt pathogen and are consistent with an antagonistic relationship between the two genes. Mutational analyses also indicate the plant wounding hormone, systemin, is not required, while jasmonic acid appears to play a direct role in Ve1 induction.
