Genome-Wide Analyses of Phosphate Transporters in Wild Rice (Oryza brachyantha) Revealed Their Evolution and...

Recently, considerable progress has been made in understanding how cultivated rice adapts to phosphate (Pi) deficiency stress. However, little has been achieved in the genetic exploration of wild rice accessions, which are crucial for the development of new varieties adapted to Pi-limited soils. In this study, we evaluated a collection of wild rice accessions for their phosphorus (P) absorption efficiencies using a hydroponic system, and identified Oryza brachyantha, a distant relative of the cultivated rice, as a promising candidate. Our investigation of phosphate transporters (PTs) in this wild species uncovered 31 ObPT genes across five families and analyzed their corresponding protein sequences. Phylogenetic and synteny analyses revealed that these ObPT proteins were highly conserved with their counterparts in cultivated rice (Oryza sativa), but six OsPT orthologs were lost from the O. brachyantha genome during its natural adaptation to the African savanna. Notably, only 24 out of 31 ObPTs were detectable by qRT-PCR assays, and these genes showed different expression patterns in roots and leaves following prolonged Pi deprivation of up to 12 days. This dynamic expression pattern suggested an efficient reutilization of high P storage in roots and leaves for an extended period, potentially explaining the superior Pi utilization strategy by O. brachyantha. In conclusion, our study identified a wild rice species with high Pi uptake efficiency and provided novel insights into the genetic diversity and evolution of PT genes in a wild rice relative, illuminating their functions in Pi homeostasis.