棉花钾离子通道基因GhAKT1在钾离子吸收和转运过程中的作用机理

摘要 : 中国农业大学田晓莉教授课题组在新研究中证实，GhAKT1基因编码了一种作为K+内向钾离子通道膜定位蛋白，阐明了GhAKT1基因在棉类作物中的表达情况和作用机理，研究结果揭示了棉花K+吸收的机理，并为提高棉花的钾营养提供了候选基因，具有非常深远的应用价值。相关文章发表于2014年7月15日的《Gene》杂志上。

shaker-K+通道家族在植物对K+吸收和转运中发挥着重要的作用，但目前K+通道在棉花中的作用机理仍不清楚。本文选取了陆地棉辽棉17的K+通道基因GhAKT1进行研究，通过非损伤微测技术(NMT)技术测量不同条件下拟南芥根分生区K+流速的差异，最终证实钾离子的内流受GhAKT1调控，且和AtAKT1一样，对Ba2+敏感。

本文通过非损伤微测技术结合绿色荧光蛋白技术以及系统发育、转录分析证实，GhAKT1基因编码了一种作为K+内向钾离子通道膜定位蛋白，阐明了GhAKT1基因在棉类作物中的表达情况和作用机理，研究结果揭示了棉花K+吸收的机理，并为提高棉花的钾营养提供了候选基因，具有非常深远的应用价值。

原文摘要：

Functional characterization of GhAKT1, a novel Shaker-like K+channel gene involved in K+ uptake from cotton (Gossypium hirsutum)

Juan Xu, Xiaoli Tian, A. Egrinya Eneji, Zhaohu Li

Shaker-like potassium (K+) channels in plants play an important role in K+ absorption and transport. In this study, we characterized a Shaker-like K+ channel gene GhAKT1 from the roots of Gossypium hirsutum cv. Liaomian17. Phylogenetic analysis showed that the GhAKT1 belongs to the AKT1-subfamily in the Shaker-like K+ channel family. Confocal imaging of a GhAKT1-green fluorescent fusion protein (GFP) in transgenicArabidopsis plants indicated that GhAKT1 is localized in the plasma membrane. Transcript analysis locatedGhAKT1 predominantly in cotton leaves with low abundance in roots, stem and shoot apex. Similarly, β-glucuronidase (GUS) activity was detected in both leaves and roots of PGhAKT1::GUS transgenicArabidopsis plants. In roots, the GUS signals appeared in the epidermis, cortex and endodermis and root hairs, suggesting the contribution of GhAKT1 to K+ uptake. In leaves, GhAKT1 was expressed in differentiated leaf primordial as well as mesophyll cells and veins of expanded leaves, pointing to its involvement in cell elongation and K+ transport and distribution in leaves. Severe K+ deficiency did not affect the expression of GhAKT1 gene. GhAKT1-overexpression in either the Arabidopsis wild-type or akt1 mutant enhanced the growth of transgenic seedlings under low K+ deficiency and raised the net K+ influx in roots at 100 μM external K+ concentration, within the range of operation of the high-affinity K+ uptake system. The application of 2 mM BaCl2 resulted in net K+ efflux in roots, and eliminated the differences betweenGhAKT1-overexpression lines and their acceptors indicating that the K+ uptake mediated by GhAKT1 is also as Ba2 +-sensitive as AtAKT1.

作者：旭月

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