Haplotypes within tandemly duplicated candidate genes at BnaA9.MRP5
modulate phytate concentration in canola (Brassica napus L.)
Phytate is the storage form of phosphorus in angiosperm seeds and plays
vitally important roles during seed development. However, in crop plants
phytate decreases bioavailability of seed-sourced mineral elements for
humans, livestock and poultry, and contributes to phosphate-related
water pollution. However, there is little knowledge about this trait in
oilseed rape B. napus (oilseed rape). Here, a panel of 505 diverse B.
napus accessions was screened in a genome-wide association study (GWAS)
using 3.28 x 106 single nucleotide polymorphisms (SNPs). This identified
119 SNPs significantly associated with phytate concentration (PA_Conc)
and phytate content (PA_Cont) and six candidate genes were identified.
Of these, BnaA9.MRP5 represented the candidate gene for the significant
SNP chrA09_5198034 (27kb) for both PA_Cont and PA_Conc. Transcription
of BnaA9.MRP5 in a low -phytate variety (LPA20) was significantly
elevated compared with a high -phytate variety (HPA972). Association and
haplotype analysis indicated that inbred lines carrying specific SNP
haplotypes within BnaA9.MRP5 were associated with high- and low-phytate
phenotypes. No significant differences in seed germination and seed
yield were detected between low and high phytate cultivars examined.
Candidate genes, favorable haplotypes and the low phytate varieties
identified in this study will be useful for low-phytate breeding of B.