Metabolic alterations proposed by proteome in rice roots grown under low P and high Al concentration under low pH

Growth inhibition caused by acid soils, especially due to P deficiency and Al stress, is a serious problem for crop production. To comprehend the adaptation mechanisms of rice plants to P deficiency and Al stress conditions, a proteomic analysis of rice roots in hydroponic cultivation was demonstrated. Four hundred and sixty-four detectable proteins spots were separated by 2D-PAGE. Fifty-six of 94 spots selected at random were identified by peptide mass fingerprinting. In general, the proteomic alterations under P deficiency and Al stress conditions were similar trend, indicating that a common metabolic system is responsive to both P deficiency and Al stress. An increase in nucleotide monomer synthesis was indicated from the related proteomic alterations, which mediate the reversible reactions of the triose phosphate/pentose phosphate pool, and the oxidative reactions of the pentose phosphate pathway under both stress conditions. Carbon flow to the TCA cycle and N assimilation were altered in proteomic level. The changes could be contributed to the complementation of TCA components from suppression of photosynthates partitioning from leaves, and partly contribute to organic acid secretion. Induction of S-adenosylmethionine (SAM) synthetase is a significant and unique response to Al stress, suggesting that SAM is related to ethylene-mediated inhibition of root growth and/or the alteration of cell wall structures and polymers in roots.