RFLP linkage analysis and mapping genes controlling the fatty acid profile of Brassica juncea using reciprocal DH populations

Abstract

An RFLP linkage map, comprising 300 linked and 16 unlinked loci, was constructed using reciprocal DH populations of Brassica juncea. The linked loci were organized into 18 linkage groups and seven unlinked segments, covering a total map distance of 1,564 cM. The A and B genomes were identified. The chi(2) test showed that 96.1% of the common intervals in the two populations differed non-significantly for recombination fractions, thus strongly suggesting the absence of sex-based differences for recombination fractions in B. juncea. Two QTLs, E(1a) and E(1b), significantly affected erucic acid content, and individually explained 53.7% and 32.1%, respectively, and collectively 85.8% of the phenotypic variation in the population. The QTLs E(1a) and E(1b) showed epistasis, and the full model including epistasis explained nearly all of the phenotypic variation in the population. The QTLs E(1a) and E(1b) were also associated with contents of oleic, linoleic and linolenic acids. Three additional QTLs (LN(2), LN(3) and LN(4)) significantly influenced linolenic acid content. The QTL LN(2) accounted for 35.4% of the phenotypic variation in the population. Epistatic interactions were observed between the QTLs E1a and LN(2). The stability of the detected QTLs across years and locations, and breeding strategies for improving the fatty acid profile of B. juncea, are discussed.

Genetic analysis of agronomic and quality traits in mustard (Brassica juncea)

“…Mukherjee et al (2001) identified two RAPD markers linked to the Albugo candida resistance locus which could be used in marker-assisted selection. Cheung et al (1998), Lionneton et al (2002) and Mahmood et al (2003a) mapped QTLs associated with the fatty acid profile in B. juncea. QTLs controlling aliphatic GSLs in mustard were mapped by Cheung et al (1998) and more recently by Mahmood et al (2003b).…”

The genetic dissection of quantitative traits in crops

“…NILs are particularly effective genetic stocks for studying phenotypic effects attributable to a QTL since the genetic background, including morphological and phenological characters that commonly influence phenotypic assessments of quantitative traits, is uniform. Double haploid (DH) populations have also been used for QTL mapping in several species (e.g., Bao et al 2002;Mahmood et al 2003;Behn et al 2005;Semagn et al 2006d;Semagn et al 2007;Xu and Crouch, 2008). The DH production methodology improves breeding efficiency by generating inbred lines with 100% purity and genetic uniformity in just two generations.…”

Inheritance of long chain fatty acid content in rapeseed (Brassica napus L.)

“…All F-tests in the mixed model were conducted using the appropriate mean squares for the error term according to Steel et al (1997). Generation means analyses (GMA) were conducted using regression analysis in SAS to estimate additive, dominance, and epistatic eVects as proposed by Hayman (1958) and Mather and Jinks (1971). The six generations used in the analysis included two non-segregating generations, P HE and P LE , and four segregating generations F 2 , F 3, BC 1 F 2 P LE , and BC 1 F 2 P HE .…”

“…Low erucic acid content is desirable in edible oils because high levels have adverse eVects on animal health (Beare et al 1963) and have been linked to growth inhibition and death when fed as a large proportion of animal diets (Thomasson and Boldingh 1955). Glucosinolates are sulfur-containing compounds that also cause health problems in animals (McKinnon and Bowland 1979). Improvement in seed and oil-processing techniques, combined with advances in plant breeding for oil quality, enabled canola oil to gain signiWcant market share as a cooking oil in the western hemisphere (Downey and Röbbelen 1989).…”