The Role Of Root Cell Wall Pectin In The Reutilization Of Endogenous Phosphorus In Plant Under Phosphorus Deficient Conditions

Mechanisms of P deficiency resistance in plants can be classified into internal P reusing and exudation mechanisms, but cellular reusing of P with the help of cell wall polysaccharides has not been well documented. Here, we demonstrated the contribution of cell wall pectin to P reusing and resistance in rice. Different P deficiency resistant between two rice cultivars was evaluated by the degree of the necrosis of the leaves and available Pi concentration. Cultivar Nipponbare showed better growth and greater soluble P content in roots than Kasalath under P deficiency, indicating that different genotypic P deficiency resistance is related to reusing the P from the insoluble P. Nipponbare had greater ability to increase the cell wall polysaccharides, especially the pectin, suggested that cell wall polysaccharides might contribute to P deficiency resistance. Genotypic differences among seventeen cultivars were correlated well with the pectin content which is in accordance with the in vitro ability of pectin to effectively desorbed the P from FePO4. Furthermore, qual-2with a lower pectin content showed P deficiency sensitive while exogenous NaCl supplied ameliorated P deficiency efficiently in company with the increment of the pectin content in Arabidopsis. These results indicated that the cell wall pectin helped to compete Fe/Al from sparing soluble Fe/Al-P, thus releasing the soluble P, which contributed to the P deficiency resistance in P resistant rice cultivar.