Genetic variation in BnGRP1 contributes to low phosphorus tolerance in Brassica napus

Abstract

The lack of phosphorus (P) is a major environmental factor affecting rapeseed root growth and development. For breeding purposes, it is crucial to identify the molecular mechanisms of root system architecture (RSA) traits underlying low P tolerance in rapeseed. Using genome-wide association study (GWAS), transcriptome and re-sequencing analyses were done on 400 rapeseed cultivars, the natural variations of glycine-rich protein gene, BnGRP1, in response to low P tolerance. Based on 11 SNP mutations in the BnGRP1 sequence, ten types of haplotypes (Hap) were formed. Compared with the other types, the cultivar of the BnGRP1Hap1 type in the panel demonstrated the longest root length and heaviest root weight. Over-expression of BnGRP1Hap1 in rapeseed depicted the ability to enhance the resistance of rapeseed in its response to low P tolerance. CRISPR/Cas9-derived BnGRP1Hap1 knockout mutations in rapeseed could lead to sensitivity to low P stress. Furthermore, BnGRP1Hap1 influenced the expression of phosphate transporter 1 (PHT1) genes associated with P absorption. Overall, the findings of this study highlight the new mechanisms of GRP1 genes in enhancing the low P tolerance in rapeseed.