Hydrogen peroxide alleviates P starvation in rice by facilitating P remobilization from the root cell wall

Phosphorus (P) deficiency limits rice production. Increasing the remobilization of P stored in the root cell wall is an efficient way to alleviate P starvation in rice. In the current study, we found that the addition of 50 μM H₂O₂ significantly increased soluble P content in rice. H₂O₂ stimulated pectin biosynthesis and increased pectin methylesterase (PME) activity, thus stimulating the release of P from the cell wall in roots. H₂O₂ also regulates internal P homeostasis by increasing the expression of P transporter genes OsPT2, OsPT6, and OsPT8 at different treatment times. In addition, the H₂O₂ treatment increased the expression of nitrate reductase (NR) genes OsNIA1 and OsNIA2 and the activity of NR, then increased the accumulation of nitric oxide (NO) in the rice root. The application of the NO donor sodium nitroprusside (SNP) and the H₂O₂ scavenger 4-hydroxy-TEMPO significantly increased soluble P content by increasing pectin levels and PME activity to enhance the remobilization of P from the cell wall. However, the addition of NO scavenger 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) with and without H₂O₂ had the opposite effect, suggesting that NO functions downstream of H₂O₂ to increase the remobilization of cell wall P in rice.