A novel aldo-keto reductase gene, OsAKR1, negatively regulates P reutilization in P deficient rice (Oryza sativa) root cell wall via a NO dependent manner.

Phosphorus (P) is an indispensable macronutrient that plants rely on for their growth and development, and P deficiency is a major constraint on rice yield and quality. Aldo-keto reductases (AKRs) play important roles in plant responses to abiotic stresses, but their function in P deficiency remains unclear. This study identified a rice aldo-keto reductase gene, OsAKR1, and revealed its negative regulatory role in P deficiency stress. Mutants deficient in OsAKR1 displayed a more pronounced phenotype of tolerance to P deficiency compared with Nip, characterized by greater root and shoot biomass and higher concentrations of soluble P and total P in both roots and shoots. In addition, OsAKR1 exhibited high expression levels in roots, and P deficiency significantly induced the transcription level of OsAKR1. Mechanistic investigations demonstrated that OsAKR1 negatively regulates rice adaptation to P deficiency by inhibiting the remobilization of P from the root cell wall, suppressing the production of the nitric oxide (NO) signal, and downregulating the expression of Oryza sativa Phosphate Transporter 2/8 (OsPT2/8). This study is the first to reveal a mechanism by which OsAKR1 modulates rice's tolerance to P deficiency through an NO-mediated cell wall P recycling pathway, providing a crucial theoretical basis and a genetic target for breeding P-efficient rice varieties.