Combined Analysis of the Leaf Metabolome, Lipidome, and Candidate Gene Function: Insights into Genotypic Variation in Phosphorus Utilization Efficiency in Stylosanthes guianensis

Stylo (Stylosanthes guianensis) exhibits excellent tolerance to low-phosphate (Pi) availability, but the underlying mechanisms responsible for improving the phosphorus (P) utilization efficiency (PUE) remain unclear. This study employed metabolomics, lipidomics, and gene expression analyses to investigate the differential responses to low-Pi stress between the high-PUE genotype CF047827 and the cultivar Reyan No. 2. Results showed that CF047827 had higher expression levels of membrane lipid remodeling-related genes in its leaves compared to Reyan No. 2 under low-Pi conditions. This was accompanied by greater phospholipid degradation and non-P-containing lipid biosynthesis in the leaves of CF047827. Furthermore, the purple acid phosphatase gene SgPAP27a, which is more highly expressed in the leaves of CF047827 than in Reyan No. 2 under low-Pi conditions, was identified and functionally characterized. Its role in promoting phospholipid degradation and enhancing PUE was confirmed through heterologous expression in Arabidopsis. These findings provide insights and identify potential candidate genes for breeding high-PUE crop cultivars.