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Superior aluminium (Al) tolerance of Stylosanthes is achieved mainly by malate synthesis through an Al‐enhanced malic enzyme, Sg ME 1
Author(s) -
Sun Lili,
Liang Cuiyue,
Chen Zhijian,
Liu Pandao,
Tian Jiang,
Liu Guodao,
Liao Hong
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12629
Subject(s) - biology , malic enzyme , arabidopsis thaliana , phaseolus , malate dehydrogenase , biochemistry , enzyme , botany , gene , mutant , dehydrogenase
SummaryStylosanthes (stylo) is a dominant leguminous forage in the tropics. Previous studies suggest that stylo has great potential for aluminium (Al) tolerance, but little is known about the underlying mechanism. A novel malic enzyme, Sg ME 1, was identified from the Al‐tolerant genotype TPRC 2001‐1 after 72 h Al exposure by two‐dimensional electrophoresis, and the encoding gene was cloned and characterized via heterologous expression in yeast, Arabidopsis thaliana and bean ( Phaseolus vulgaris ) hairy roots. Internal Al detoxification might be mainly responsible for the 72 h Al tolerance of TPRC 2001‐1, as indicated by 5.8‐fold higher root malate concentrations and approximately two‐fold higher Al concentrations in roots and root symplasts of TPRC 2001‐1 than those of the Al‐sensitive genotype Fine‐stem. An accompanying increase in malate secretion might also reduce a fraction of Al uptake in TPRC 2001‐1. Gene and protein expression of Sg ME 1 was only enhanced in TPRC 2001‐1 after 72 h Al exposure. Overexpressing Sg ME 1 enhanced malate synthesis and rescued yeast, A. thaliana and bean hairy roots from Al toxicity via increasing intracellular malate concentrations and/or accompanied malate exudation. These results provide strong evidence that superior Al tolerance of stylo is mainly conferred by Al‐enhanced malate synthesis, functionally controlled by Sg ME 1 .