title: Dissecting quantitative trait loci for boron efficiency across multiple environments in Brassica napus.
abstract: High yield is the most important goal in crop breeding, and boron (B) is an essential micronutrient for plants. However, B deficiency, leading to yield decreases, is an agricultural problem worldwide. Brassica napus is one of the most sensitive crops to B deficiency, and considerable genotypic variation exists among different cultivars in response to B deficiency. To dissect the genetic basis of tolerance to B deficiency in B. napus, we carried out QTL analysis for seed yield and yield-related traits under low and normal B conditions using the double haploid population (TNDH) by two-year and the BQDH population by three-year field trials. In total, 80 putative QTLs and 42 epistatic interactions for seed yield, plant height, branch number, pod number, seed number, seed weight and B efficiency coefficient (BEC) were identified under low and normal B conditions, singly explaining 4.15-23.16% and 0.53-14.38% of the phenotypic variation. An additive effect of putative QTLs was a more important controlling factor than the additive-additive effect of epistatic interactions. Four QTL-by-environment interactions and 7 interactions between epistatic interactions and the environment contributed to 1.27-4.95% and 1.17-3.68% of the phenotypic variation, respectively. The chromosome region on A2 of SYLB-A2 for seed yield under low B condition and BEC-A2 for BEC in the two populations was equivalent to the region of a reported major QTL, BE1. The B. napus homologous genes of Bra020592 and Bra020595 mapped to the A2 region and were speculated to be candidate genes for B efficiency. These findings reveal the complex genetic basis of B efficiency in B. napus. They provide a basis for the fine mapping and cloning of the B efficiency genes and for breeding B-efficient cultivars by marker-assisted selection (MAS).
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Zunkang
authors.initials: Z
authors.lastname: Zhao
authors.forename: Likun
authors.initials: L
authors.lastname: Wu
authors.forename: Fuzhao
authors.initials: F
authors.lastname: Nian
authors.forename: Guangda
authors.initials: G
authors.lastname: Ding
authors.forename: Taoxiong
authors.initials: T
authors.lastname: Shi
authors.forename: Didi
authors.initials: D
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Fangsen
authors.initials: F
authors.lastname: Xu
authors.forename: Jinling
authors.initials: J
authors.lastname: Meng
mesh_terms: D000483:Alleles; D001895:Boron / Q000172:deficiency*; D029688:Brassica napus / Q000235:genetics*; D001947:Breeding; D002874:Chromosome Mapping; D004777:Environment; D004843:Epistasis, Genetic; D014644:Genetic Variation; D005838:Genotype; D006238:Haploidy; D010641:Phenotype; D040641:Quantitative Trait Loci; D012639:Seeds / Q000235:genetics*
chemical_list: D001895:Boron