Mapping the virus and host genes involved in the resistance response in cucumber mosaic virus-infected Arabidopsis thaliana

A yellow strain of cucumber mosaic virus (CMV) [CMV(Y)] induces a resistanc e response characterized by inhibition of virus systemic movement with deve lopment of necrotic local lesions in the virus-inoculated leaves of Arabido psis thaliana ecotype C24, In this report, the avirulence determinant in th e virus genome was defined and the resistance gene (RCY1) of C24 was geneti cally mapped. The response of C24 to CMV containing the chimeric RNA3 betwe en CMV(Y) and a virulent strain of CMV indicated that the coat protein gene of CMV(Y) determined the localization of the virus in the inoculated leave s of C24, The RCY1 locus was mapped between two CAPS markers, DFR and T4396 8, which were located in the region containing genetically defined disease resistance genes and their homologues, These results indicate that the resi stance response to CMV(Y) in C24 is determined by the combination of the co at protein gene and RCY1 on chromosome 5.