Phosphoenolpyruvic Carboxylase Gene GmPPC6 Negatively Regulates Root System Development Under Low Phosphorus Stress in Soybean.

Available phosphorus (P) deficiency in soil is one of the major factors limiting the growth and development of soybean. Although great efforts have been made to identify QTLs or genes related to low P stress in soybean, few studies have been reported on the root remodeling. Here, by performing genome-wide association study (GWAS) using 239 accessions and 62 124 single-nucleotide polymorphism (SNP) markers, 194 QTN regions related to seven root traits were screened, and 5 of 194 were colocated in at least three traits or environments. By performing comparative transcriptome analysis using low phosphorus tolerant genotype P375 and sensitive genotype P018 under low P stress, 621 DEGs were identified between normal and low P treatment and 1025 DEGs between P375 and P018. The integrated analysis of candidate genes within both QTLs and DEGs showed that GmPPC6 could be a staple gene. Overexpression and RNA interference of GmPPC6 in transgenic hairy roots indicated that GmPPC6 negatively affected root length (RL) and root surface area (SA) under low P stress. Together, this study further elucidates the systemic changes in genes induced by low P stress and provides valuable insight into the great potential of GmPPC6 under low P stress in soybean.