Nitrate inhibits the remobilization of cell wall phosphorus under phosphorus-starvation conditions in rice (Oryza sativa)
NO3− not only inhibited the reutilization of cell wall P via decreasing root cell wall pectin content and PME activity, but also hampered the P translocation from root to shoot.
The rice cultivars ‘Kasalath’ (Kas) and ‘Nipponbare’ (Nip) were used to demonstrate that the nitrogen source NO3− inhibits internal phosphorus (P) reutilization in rice under P-absence conditions. Analysis using Kas showed that the expression of − P-induced marker genes OsIPS1/2 and OsSPX1/2/3/5 are significantly higher under 1 mM NO 3 − − P (1N − P) treatment than 0 mM NO 3 − − P (0N − P) treatment. The absence of NO3− from the nutrient solution significantly increased cell wall P release by increasing pectin synthesis and increasing the activity of pectin methylesterase (PME), and also significantly improved the translocation of soluble P from the root to the shoot by increasing xylem sap P content under P-absence conditions. The rice seedlings grown in 0 mM NO3− accumulated significantly higher nitric oxide (NO) in the roots than those grown in 1 mM NO3−. Exogenously applying the NO donor sodium nitroprusside (SNP) revealed that NO is a major contributor to differential cell wall P remobilization in rice by mediating pectin synthesis and demethylation under different NO3− concentrations (0 and 1 mM) under P-deprived conditions.
KeywordsCell wall Nitrate (NO3−) Nitric oxide (NO) Phosphorus (P) Remobilization Rice Translocation
This work was funded by the National Key Basic Research Program of China (Grant number 2014CB441000), the Natural Science Foundation of China (Grant number 31501825), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant numbers XDB15030302 and XDB15030202).
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