Oilseed rape (Brassica napus) is one of the most important oil crops worldwide. Phosphorus (P) deficiency severely decreases the plant height and branch number of Brassica napus. However, the genetic bases controlling plant height and branch number in B. napus under P deficiency remain largely unknown. Liu et al. aimed to mine candidate genes for plant height and branch number by genome-wide association study (GWAS) and determine low-P-tolerance haplotypes.
An association panel of B. napus was grown in the field with a low P supply (P, 0 kg ha−1) and a sufficient P supply (P, 40 kg ha−1) across 2 years and plant height and branch number were investigated. More than five million single-nucleotide polymorphisms (SNPs) were used to conduct GWAS of plant height and branch number at two contrasting P supplies.
A total of 2127 SNPs were strongly associated (P < 6·25 × 10−07) with plant height and branch number at two P supplies. There was significant correlation between phenotypic variation and the number of favourable alleles of associated loci on chromosomes A10 (chrA10_821671) and C08 (chrC08_27999846), which will contribute to breeding improvement by aggregating these SNPs. BnaA10g09290D and BnaC08g26640D were identified to be associated with chrA10_821671 and chrC08_27999846, respectively. Candidate gene association analysis and haplotype analysis showed that the inbred lines carrying ATT at BnaA10g09290Hap1 and AAT at BnaC08g26640Hap1 had greater plant height than lines carrying other haplotype alleles at low P supply.
These significant SNP loci, favourable alleles and haplotypes, and the accessions carrying these desired alleles and haplotypes will be useful for breeding for low-P-tolerance B. napus cultivars.
Liu, H., Wang, J., Zhang, B., Yang, X., Hammond, J.P., Ding, G., Wang, S., Cai, H., Wang, C., Xu, F., Shi, L., 2021. Genome-wide association study dissects the genetic control of plant height and branch number in response to low-phosphorus stress in Brassica napus. Annals of Botany. https://doi.org/10.1093/aob/mcab115