Genome-wide and candidate gene association studies identify BnPAP17 as conferring the utilization of organic phosphorus in oilseed rape

Phosphorus (P) is essential for living plants, and P deficiency is one of the key factors limiting the yield in rapeseed production worldwide. As the most important organ for plants, root morphology traits (RMTs) play a key role in P absorption. To investigate the genetic variability of RMT under low P availability, we dissected the genetic structure of RMTs by genome-wide association studies (GWAS), linkage mapping and candidate gene association studies (CGAS). A total of 52 suggestive loci were associated with RMTs under P stress conditions in 405 oilseed rape accessions. The purple acid phosphatase gene BnPAP17 was found to control the lateral root number (LRN) and root dry weight (RDW) under low P stress. The expression of BnPAP17 was increased in shoot tissue in P-efficient cultivars compared to root tissue and P-inefficient cultivars in response to low P stress. Moreover, the haplotype of BnPAP17Hap3 was detected for the selective breeding of P efficiency in oilseed rape. Over-expression of the BnPAP17Hap3 could promote the shoot and root growth with enhanced tolerance to low P stress and organic phosphorus (Po) utilization in oilseed rape. Collectively, these findings increase our understanding of the mechanisms underlying BnPAP17-mediated low P stress tolerance in oilseed rape.