Genetic variation in the glycine-rich protein gene BnGRP1 contributes to low phosphorus tolerance in Brassica napus

Abstract

Lack of phosphorus (P) is a major environmental factor affecting rapeseed (Brassica napus. L) root growth and development. For breeding purposes, it is crucial to identify the molecular mechanisms underlying root system architecture traits that confer low-P tolerance in rapeseed. Natural variations in the glycine-rich protein gene BnGRP1 were analysed in the natural population of 400 rapeseed cultivars under low-P stress through genome-wide association study and transcriptome analysis. Based on 11 single nucleotide polymorphism mutations in the BnGRP1 sequence, 10 haplotypes (Hap) were formed. Compared with the other types, the cultivar BnGRP1Hap1 in the panel demonstrated the longest root length and heaviest root weight. BnGRP1Hap1 overexpression in rapeseed led to enhanced low-P tolerance. CRISPR/Cas9-derived BnGRP1Hap4 knockout mutations in rapeseed can lead to sensitivity to low-P stress. Furthermore, BnGRP1Hap1 influences the expression of the phosphate transporter 1 gene (PHT1) associated with P absorption. Overall, the findings of this study highlight new insights into the mechanisms of GRP1 enhancement of low-P tolerance in rapeseed.

Keywords: Brassica napus; CRISPR/Cas9; genome-wide association study (GWAS); glycine-rich protein; haplotypes; low phosphorus tolerance; root system architecture traits.