Mapping boron efficiency gene(s) in Brassica napus using RFLP and AFLP markers

Soil boron (B) deficiency, a world-wide problem in agriculture, exists for more than 33 million hectares of cultivated land in China. Genetic variation exists for B-cfflciency among different Brassica napus germplasms. To identify genes controlling B efficiency, an F-2 population of B. napus was constructed from a cross between a high B-efficiency cultivar, 'Qingyou 10', and a low B-efficiency cultivar, 'Bakow', and then evaluated for seed yield, bolting date and maturity date under B-deficient conditions. The ratio of high B-efficiency to low B-efficiency individuals fitted the expected ratio of 3 : 1, indicating a major gene controlling the B-efficiency trait. The major gene was mapped in the ninth linkage group of B. napus. Genome-wide quantitative trait loci (QTL) analyses detected one major locus near the major gene, which explained 64.0% of the phenotypic variance, At the same time, three minor loci in three linkage groups were also detected, and these minor loci individually explained 39.2%, 32.5% and 36.9%, respectively, of the phenotypic variance. A total of 11 QTLs were detected for bolting date and maturity date, some of which were associated with B-efficiency.