RFLP MAPPING OF QUANTITATIVE TRAIT LOCI CONTROLLING SEED ALIPHATIC-GLUCOSINOLATE CONTENT IN OILSEED RAPE (BRASSICA-NAPUS L)

We report the RFLP mapping of quantitative trait loci (QTLs) which reg ulate the total seed aliphatic-glucosinolate content in Brassica napus L. A population of 99 F-1-derived doubled-haploid (DH) recombinant li nes from a cross between the cultivars Stellar (low-glucosinolate) and Major (high-glucosinolate) was used for single-marker analysis and th e interval mapping of QTLs associated with total seed glucosinolates. Two major loci, GSL-1 and GSL-2, with the largest influence on total s eed aliphatic-glucosinolates, were mapped onto LG 20 and LG 1, respect ively. Three loci with smaller effects, GSL-3, GSL-4 and GSL-5, were t entatively mapped to LG 18, LG 4 and LG 13, respectively. The QTLs act ed in an additive manner and accounted for 71% of the variation in tot al seed glucosinolates, with GSL-1 and GSL-2 accounting for 33% and 17 %, respectively. The recombinant population had aliphatic-glucosinolat e levels of between 6 and 160 mu moles per g(-1) dry wt of seed. Trans gressive segregation for high seed glucosinolate content was apparent in 25 individuals. These phenotypes possessed Stellar alleles at GSL-3 and Major alleles at the four other GSL loci demonstrating that low-g lucosinolate genotypes (i.e. Stellar) may possess alleles for high glu cosinolates which are only expressed in particular genetic backgrounds . Gsl-elong and Gsl-alk, loci which regulate the ratio of individual a liphatic glucosinolates, were also mapped. Gsl-elong-1 and Gsl-elong-2 , which control elongation of the alpha-amino-acid precursors, mapped to LG Is and LG 20 and were coincident with GSL loci which regulate to tal seed aliphatic glucosinolates. A third tentative QTL, which regula tes side-chain elongation, was tentatively mapped to LG 12. Gsl-alk, w hich regulates H3CS- removal and side-chain de-saturation, mapped to L G 20.