Genetic Control of the Root System Traits in Oilseed Rape Under Contrasting Phosphate Supply Conditions by Genome-wide Association Study.

Phosphorus (P) deficiency is a major factor constraining plant growth and yield production worldwide because it is essential for living cells and organisms. To avoid disadvantageous genetic correlations between growth duration and root system, traits are critical in developing oilseed rape cultivars that use P efficiently. To understand the genetic basis underlying the correlations between root system traits and two levels of P availability in oilseed, we investigated 6091 different expression genes in the shoot and root tissues of the cultivar Eyou Changjia under low and normal P conditions. Subsequently, the Illumina Brassica 60 K single-nucleotide polymorphism (SNP) arrays were used in a diverse and representative core collection of 405 cultivated oilseed rape accessions, and nearly 13,340 functional SNPs with high polymorphisms were genotyped at the threshold interval of candidate genes. Four root system traits were investigated in the oilseed rape accessions in both low and normal P environments. A total of 224 suggestive association loci were identified for root system traits under low and normal P conditions. Eleven were co-located with the interval of quantitative trait loci (QTLs) for the same traits detected in previous studies. Mutation of co-located SNPs with favourable alleles leads to gene sequence mutations or gene expression changes that result in different phenotypes. The interaction between multiple optimal loci and the effect of QTL aggregation of combined haplotype types with C(A3) and A(A7) formed optimal haplotypes and could improve our understanding of molecular mechanisms underlying P efficiency in oilseed rape. [ABSTRACT FROM AUTHOR]