AtALMT3 is Involved in Malate Efflux Induced by Phosphorus Deficiency in Arabidopsis thaliana Root Hairs
AtALMT3 is Involved in Malate Efflux Induced by Phosphorus Deficiency in Arabidopsis thaliana Root Hairs
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DOI：
10.1093/pcp/pcy190
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发表时间：
2019-01-01
影响因子：
4.9
通讯作者：
Wasaki, Jun
中科院分区：
文献类型：
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作者：
Maruyama, Hayato;Sasaki, Takayuki;Wasaki, Jun
在缺磷（P）条件下，根系分泌有机酸在土壤中难溶性磷的活化过程中起着重要作用。在本研究中，我们对拟南芥铝激活苹果酸转运蛋白家族基因的同源基因AtALMT3进行了特性分析。在14个AtALMT家族基因中，只有AtALMT3在缺磷的根系中显著上调。AtALMT3启动子::β - 葡萄糖醛酸酶在根的表皮中表达，尤其在根毛细胞中。AtALMT3蛋白定位于质膜和小囊泡中。原生质体裂解后，在液泡膜上未观察到AtALMT3::绿色荧光蛋白（GFP）的荧光，这表明AtALMT3主要定位于质膜。与野生型（WT）植株相比，在缺磷条件下，AtALMT3基因敲低株系（atalmt3 - 1）和过表达株系（atalmt3 - 2）的苹果酸渗出量分别为37%和126%。相比之下，这些株系之间柠檬酸渗出量没有显著差异。atalmt3 - 1株系经AtALMT3基因互补后，苹果酸渗出量恢复到野生型水平。综上所述，这些结果表明定位于根毛膜的AtALMT3参与了缺磷响应中的苹果酸外排。
Under phosphorus (P)-deficient conditions, organic acid secretion from roots plays an important role in P mobilization from insoluble P in the soil. In this study, we characterized AtALMT3, a homolog of the Arabidopsis thaliana aluminum-activated malate transporter family gene. Among the 14 AtALMT family genes, only AtALMT3 was significantly upregulated in P-deficient roots. AtALMT3 promoter::beta-glucuronidase is expressed in the epidermis in roots, especially in root hair cells. AtALMT3 protein was localized in the plasma membrane and in small vesicles. Fluorescence of AtALMT3::GFP was not observed on the vacuole membrane of protoplast after lysis, indicating that AtALMT3 localizes mainly in the plasma membrane. Compared with the wildtype (WT) line, malate exudation in the AtALMT3-knockdown line (atalmt3-1) and overexpression line (atalmt3-2) under P deficiency were, respectively, 37% and 126%. In contrast, no significant difference was found in citrate exudation among these lines. The complementation of the atalmt3-1 line with AtALMT3 recovered the malate exudation to the level of the WT. Taken together, these results suggest that AtALMT3 localized in root hair membranes is involved in malate efflux in response to P deficiency.