Screening Sunflower for Resistance to Sunflower chlorotic mottle virus and Mapping the Rcmo‐1 Resistance Gene

Sunflower chlorotic mottling is an emerging virus disease which has been detected in commercial hybrids and wild sunflowers in Argentina. Two hundred thirty‐two sunflower (Helianthus annuus L.) lines were screened for resistance to Sunflower chlorotic mottle virus (SuCMoV) using artificial inoculations under greenhouse conditions. Only three lines (L33, L74, and L52) showed a partial resistance, L33 being the most resistant. Virus replication was delayed (A405 in DAS‐ELISA) and morphological traits (plant height and leaf width) were less affected in this line and its various hybrid combinations than in susceptible controls. Segregation data from an artificially inoculated F2 population, under greenhouse and field conditions, indicated the presence of a single dominant resistance gene which was designated Rcmo‐1 This gene was mapped on Linkage Group 14 between markers MS0022 (5 cM) and ORS‐307 (4 cM). Linkage between the two markers and the Rcmo‐1 locus was confirmed in a field evaluation.