A major quantitative trait allele for resistance to the Sugarcane yellow leaf virus (Luteoviridae)

With 1 figure and 1 table Abstract The yellow leaf disease of sugarcane is distributed worldwide and causes important yield losses. This disease is caused by a member of the Luteoviridae family, the Sugarcane yellow leaf virus (SCYLV). The objective of this study was to characterize genetic factors for resistance to yellow leaf disease in a sugarcane clone resistant to infection by SCYLV. We analysed a progeny of 196 clones obtained from a cross between the susceptible cultivar R570 and the resistant cultivar MQ76-53. This progeny was assessed for virus incidence using tissue-blot immunoassay after 10 years of cultivation under natural infection conditions. The progeny was genotyped with various types of molecular markers resulting in 2822 polymorphic markers. Marker/trait association analysis revealed that SCYLV resistance in MQ76-53 is controlled by Ryl1, a major quantitative trait allele (QTA) accounting for 32% of the phenotypic variance. Ryl1 is the first major QTA described to control a viral disease in sugarcane, and MQ76-53 can already be used to introgress SCYLV resistance derived from Ryl1 in elite germplasm.