AtALMT1, which encodes a malate transporter, is identified as one of several genes critical for aluminum tolerance in Arabidopsis
AtALMT1, which encodes a malate transporter, is identified as one of several genes critical for aluminum tolerance in Arabidopsis
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DOI：
10.1073/pnas.0602868103
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发表时间：
2006-06-20
影响因子：
11.1
通讯作者：
Kochian, Leon V.
中科院分区：
文献类型：
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作者：
Hoekenga, Owen A.;Maron, Lyza G.;Kochian, Leon V.
拟南芥的铝 (Al) 耐受性是一种遗传复杂性状，但它是由基于铝激活的根苹果酸流出的单一生理机制介导的。我们研究了铝耐受性的可能分子决定因素，涉及小麦铝激活的苹果酸转运蛋白 ALMT1 的同源物。该基因被命名为 AtALMT1(At1 g08430)，根据表达模式和基因组位置，它是 AtALMT 家族 14 个成员中与 Al 耐受性相关的最佳候选基因。对 AtALMT1 转移 DNA 敲除突变体的生理分析以及爪蟾卵母细胞中表达的蛋白质的电生理检查表明，AtALMT1 对于拟南芥 Al 耐受性至关重要，并编码与耐受性相关的 Al 激活的根苹果酸外流转运蛋白。然而，来自耐受哥伦比亚 (Col)、敏感兰茨伯格直立 (Ler) 和铝耐受性不同的其他生态型的 AtALMT1 等位基因的基因表达和序列分析表明，AtALMT1 观察到的变异与这些生态型之间观察到的铝耐受性差异无关。遗传互补实验表明，AtALMT1 的 Ler 等位基因在赋予铝耐受性和铝激活的苹果酸释放方面与 Col 等位基因同样有效。最后，1 号染色体上铝耐受性数量性状基因座 (QTL) 的精细定位表明，AtALMT1 位于该 QTL 附近。这些结果表明AtALMT1是拟南芥AI耐受性的一个重要因素，但并不代表在1号染色体上也发现的主要AI耐受性QTL。
Aluminum (Al) tolerance in Arabidopsis is a genetically complex trait, yet it is mediated by a single physiological mechanism based on Al-activated root malate efflux. We investigated a possible molecular determinant for Al tolerance involving a homolog of the wheat Al-activated malate transporter, ALMT1. This gene, named AtALMT1(At1 g08430), was the best candidate from the 14-member AtALMT family to be involved with Al tolerance based on expression patterns and genomic location. Physiological analysis of a transferred DNA knockout mutant for AtALMT1 as well as electro-physiological examination of the protein expressed in Xenopus oocytes showed that AtALMT1 is critical for Arabidopsis Al tolerance and encodes the Al-activated root malate efflux transporter associated with tolerance. However, gene expression and sequence analysis of AtALMT1 alleles from tolerant Columbia (Col), sensitive Landsberg erecta (Ler), and other ecotypes that varied in Al tolerance suggested that variation observed at AtALMT1 is not correlated with the differences observed in Al tolerance among these ecotypes. Genetic complementation experiments indicated that the Ler allele of AtALMT1 is equally effective as the Col allele in conferring Al tolerance and Al-activated malate release. Finally, fine-scale mapping of a quantitative trait locus (QTL) for Al tolerance on chromosome 1 indicated that AtALMT1 is located proximal to this QTL. These results indicate that AtALMT1 is an essential factor for AI tolerance in Arabidopsis but does not represent the major Al tolerance QTL also found on chromosome 1.