Reactions and Virus Titres of Differential Sorghum Inbred Lines Mechanically Inoculated with an Indian Isolate of Sorghum Red Stripe Potyvirus (SRSV-Ind)

摘要

A potyvirus naturally infecting sorghum grown near sugarcane in Maharashtra, India, was identified as belonging to a sugarcane mosaic virus (SCMV) subgroup and designated SRSV-Ind. It was characterized by systemic necrotic red stripe symptoms in a number of sorghum genotypes. In a test of 18 sorghum differentials, SRSV-Ind (isolated from sugarcane cv. Co740 and maintained on immune sorghum line Tx2786) induced systemic necrotic red stripe reactions (disease severity reaction (DSR) = 4) in differentials Redlan, Hegari, QL3/India and SCO175-14E, mild mosaic (DSR = 2) in differentials RTx 09, Martin, Caprock and RTx7078, and severe mosaic (DSR = 3) in differentials NM31, BTx623, QL11, PI35038, BTx3048, Rio, Tx2786, Atlas, SA394 and Cargill 40. Positive correlations between infectivity levels (IL), disease severity reactions (DSR) and virus titres (VT) were found in only 2 differentials (Cargill 40 and SCO175-14E) infected mechanically. SRSV-Ind was distinct from maize dwarf mosaic virus-B (MDMV-B; SCMV-MDB) in infecting 9 differentials known to be resistant to MDMV-B, from SrMV in infecting 3 differentials (Tx2786, QL3 and QL11) known to be resistant to well characterized SCMV strains, and from MDMV-A in infecting QL11 known to be resistant to MDMV-A.