Résumé
The spotted stem borer (SSB) Chilo sacchariphagus is a major pest of sugarcane, causing substantial losses in cane weight and in sucrose yield. SSB resistance is an important trait to be taken into account for sugarcane breeding programs. In order to analyse the genetic basis of the resistance to SSB, we undertook a quantitative trait allele (QTA) mapping study based on a population of 147 progenies derived from the selfing of the resistant modern cultivar R570. The experimental population was evaluated in a replicated trial for borer damage under natural infestation in two successive crop cycles. A single-factor analysis using 1,405 polymorphic markers was performed to detect marker-trait associations. Statistical thresholds based on permutation tests designed to control type I errors at a low level allowed the detection of nine QTAs whose individual size ranged between 6 and 10% of the total variation. These nine QTAs are distributed over five of the eight homeology groups of the polyploid R570 genome. Two QTAs were found to co-localize with two typical resistance gene analog clusters. Overall, eight QTAs explain altogether 42% of the total phenotypic variance.