QTL analysis for diamondback moth resistance in canola (Brassica napus L.)

Diamondback moth (DBM), Plutella xylostella L. is the most injurious defoliage insect pest of canola in Ardabil province of Iran. It occurs annually and causes damage in canola fields. This study was performed to identify QTLs controlling resistance to diamondback moth using SSR and RAPD markers. An F2:4 population of 180 families derived from crossing between cv. ‘SLMO46’ and cv. ‘Quantum’ were used. The number of DBM eggs (EPL) and larvae per leaf (LPL) were recorded in each F4 families on 10 randomly selected plants at rosette stage. The intensity of damage (ID) was scored as 0 to 4 according to the relative size of leaf eaten area. QTL analysis was performed using the previously constructed linkage map of SSR and RAPD markers. QTL mapping based on composite interval mapping (CIM) method identified seven QTLs for the studied traits. The explained phenotypic variance by the QTLs ranged from 13 to 35%. The QTLs showed positive and negative additive effects and inherited from both parents to the progenies. Three QTLs on linkage group three were common for LPL, EPL and ID indicating pleiotropic gene effect or linked genes for these traits. Two QTLs on linkage group 14 were also common between studied traits.