Identification, Mapping, and Economic Evaluation of QTLs Encoding Root Maggot Resistance inBrassica

Abstract

Commercial varieties of canola (Brassica napus L. and B rapa L.) are susceptible to infestations by the root maggots Delia radicum (L.) and Delia floralis (Fallén) (Diptera: Anthomyiidae) in western Canada. Although cultural strategies can ameliorate crop damage from root maggot infestations, these methods are not sufficiently effective to prevent substantial economic losses. In this paper we report the development of germplasm for resistance to root maggot infestations and the introgression of genes from a resistant relative (Sinapis alba L.) to susceptible B napus The effectiveness of the conferred resistance to root maggot damage was validated by comparing different genotypes for pest damage and yield loss with and without insecticide applications. Yield of B napus plants, susceptible to root maggot infestations, increased when insecticide was applied (by up to 24%), but no significant yield differences were observed among resistant intergeneric hybrids that were treated or not treated with insecticide. One hundred and thirty‐five restriction fragment length polymorphisms (RFLPs) were used to construct a B. napus genetic linkage map and to identify quantitative trait loci (QTLs) associated with resistance to root maggot damage. Two QTLs, RM‐G8 and RM‐G4, were found to be associated with resistance to root maggot damage. Together, these two QTLs explain 54.6% of the total variation observed.

Potential for oilseed rape resistance in pollen beetle control

“…This is not surprising, since S. alba has been shown to be resistant to several other insect pests of OSR: root flies Delia spp. (Dosdall et al 1994), for which introgression of resistance into elite varieties has also been achieved Kott and Dosdall 2004;Ekuere et al 2005), the flea beetle P. cruciferae (Bodnaryk and Lamb 1991;Gavloski et al 2000) and the bertha armyworm Mamestra configurata (Ulmer et al 2001).…”

Breeding of rutabaga (Brassica napus var. napobrassica L. Reichenb.) based on biomarker selection for root maggot resistance (Delia radicum L.)

“…They explain 54.6% of the phenotypic variation. The RM-G8 QTL was further found linked to the SD-G8 marker for basal stem diameter with a correlation of r = 0.74 which revealed dependence between the cabbage maggot preferences and stem size (Ekuere et al 2005).…”

“…Understanding of variation on the basis of QTLs can be extended to individual genes or through integrative studies to link the loci to the phenotypic variations at the protein or metabolite level (Kott and Dosdall 2004;Ekuere et al 2005). Currently two QTLs are described in B. napus, RM-G8 and RM-G4 from this S. alba 9 B. napus material.…”

Application of doubled haploid technology in breeding of Brassica napus

“…Q2, the check genotype. Subsequently developed DH lines were used to identify quantitative trait loci for resistance to root maggot damage (Ekuere et al, 2005). Two quantitative trait loci (QTL) on a molecular marker linkage map that explain 55% of the variance for this trait were identifi ed.…”