Arabidopsis thaliana branching enzyme 1 is essential for amylopectin biosynthesis and cesium tolerance

文献类型： 外文期刊

第一作者： Zhang, Junxia

作者： Zhang, Junxia;Yang, Ju;Yang, Qihui;Gao, Hairong;Wang, Yufen;Qi, Zhi;Yang, Ju;Qi, Zhi;Yang, Ju;Cheng, Hongmei;Qi, Zhi;Zhang, Ting;Jin, Huiqing

作者机构：

关键词： Arabidopsis thaliana; Amylopectin; Branching enzyme; Cesium tolerant

期刊名称：JOURNAL OF PLANT PHYSIOLOGY （ 影响因子：3.549； 五年影响因子：4.164 ）

ISSN： 0176-1617

年卷期： 2020 年 252 卷

页码：

收录情况： SCI

摘要： Arabidopsis thaliana BRANCHING ENZYME 1 (AtBE1) is a chloroplast-localized embryo-lethal gene previously identified in knockout mutants. AtBE1 is thought to function in carbohydrate metabolism; however, this has not been experimentally demonstrated. Chlorosis is a typical symptom of cesium (Cs) toxicity in plants. The genetic target of Cs toxicity is largely unknown. Here, we isolated a Cs+-tolerant and chlorophyll-defective Arabidopsis ethyl methanesulfonate (EMS) mutant, atbel-5. Mapping by sequencing and genetic complementation confirmed that a single amino acid change (P749S) in a random coil motif of AtBE1 confers the mutant's Cs+-tolerant and chlorophyll-defective phenotype. An isothermal titration calorimetry assay determined that the 749th residue is the Cs+-binding site and hence likely the target of Cs+ toxicity. We hypothesized that binding of Cs+ to the 749th residue of AtBE1 inhibits the enzyme's activity and confers Cs+ toxicity, which in turn reduces photosynthetic efficiency. In support with this hypothesis, atbel-5 leaves have a reduced photosynthetic efficiency, and their amylose and amylopectin contents are similar to 60 % and similar to 1%, respectively, of those in Col-0 ecotype leaves. Leaves of the mutant have a lower sucrose, but higher maltose, concentration than those of Col-0. This study demonstrated that AtBE1 is an essential gene for amylopectin and amylose biosynthesis, as well as the target of Cs+ toxicity; therefore, it can serve as a genetic locus for engineering plants to extract Cs+ from contaminated soil while maintaining growth.

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