Resistance to Cucumber mosaic virus in Arabidopsis Conferred by RCY1

Extensive examination of 12 Arabidopsis ecotypes identified a CMV-Y-resistant ecotype, C24. The resistance response of C24 includes suppression of virus multiplication to a low level, the formation of necrotic lesions at the primary site of virus infection, and restriction of virus to the inoculated leaves. This resistance response in C24 is controlled by a single dominant RCY1 (resistance to cucumber mosaic virus strain Y) gene. The analysis of a series of chimeric viruses constructed from the avirulent isolate CMV-Y and the virulent isolate CMV-B2 revealed that the coat protein of CMV-Y serves as the avirulent determinant of resistance in C24. The RCY1 gene has been mapped in Arabidopsis within the MRC-5 region on chromosome 5, in which nine other defined resistance genes (RAC3, RPS4, HRT, TTR1, and five distinct RPP loci) are located. Fine mapping and sequence comparison of this region from C24 and a CMV-Y susceptible C24 mutant identified the RCY1 gene encoding 104-kDa CC-NBS-LRR type protein.

RCY1 is allelic to the resistance gene RPP8 against Peronospora parasitica in the ecotype Lansberg erecta and HRT against TCV in the ecotype Dijon-17. The RCY1-conferred resistance requires both salicylic acid and ethylene signaling but not jasmonic acid signaling. Table 4 shows some of the R gene and Avr factor pairs.