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Isolation and functional analysis of MdCS1: a gene encoding a citrate synthase in Malus domestica (L.) Borkh

Han, Deguo, Shi, Yan, Yu, Zeyuan, Liu, Wei, Lv, Bingyu, Wang, Bing, Yang, Guohui
Plant growth regulation 2015 v.75 no.1 pp. 209-218
Arabidopsis, Malus domestica, abscisic acid, amino acids, cell membranes, chlorophyll, citrate (si)-synthase, citric acid, gene overexpression, genes, genetically modified organisms, indole acetic acid, iron, isoelectric point, leaves, molecular weight, phloem, seedlings
Iron (Fe) is one of the essential micronutrients required by all plants. Citric acid (CA) is considered as the chelate substance in the long distance transport of Fe. In the present study, a gene encoding putative citrate synthase (CS) was isolated from Malus domestica (L.) Borkh and designated as MdCS1. The MdCS1 gene encodes a protein of 473 amino acid residues with a theoretical isoelectric point of 7.72 and a predicted molecular mass of 52.7 kDa. Subcellular localization has revealed that MdCS1 is preferentially localized in cytoplasmic membrane. The expression of MdCS1 was enriched in leaf, root, and phloem, which was highly affected by Fe stress and indoleacetic acid treatment, while weakly by abscisic acid treatment in M. domestica seedlings. When MdCS1 was introduced into Arabidopsis, it promoted the synthesis of CS and increased CA content. Overexpression of MdCS1 improved the tolerance to Fe stress in transgenic Arabidopsis, but also led to increased fresh weight, CS activity, and contents of chlorophyll, CA and Fe, especially when dealt with Fe stress.