Salinity-induced expression of HKT may be crucial for Na+ exclusion in the leaf blade of huckleberry (Solanum scabrum Mill.), but not of eggplant (Solanum melongena L.)
Salinity-induced expression of HKT may be crucial for Na+ exclusion in the leaf blade of huckleberry (Solanum scabrum Mill.), but not of eggplant (Solanum melongena L.)
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DOI：
10.1016/j.bbrc.2015.03.048
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发表时间：
2015-05-01
影响因子：
3.1
通讯作者：
Saneoka, Hirofumi
中科院分区：
文献类型：
--
作者：
Assaha, Dekoum V. M.;Mekawy, Ahmad Mohammad M.;Saneoka, Hirofumi
叶片中Na+积累的减少是耐盐性的一个重要方面，高亲和力K+转运蛋白（HKT）在此过程中起着重要作用。越橘和茄子在盐胁迫下分别表现出“排斥”和“包容”的特性，但其内在机制尚未研究。本研究克隆了HKT同源基因--越橘中的粗糙茄HKT（Solanum scabrum HKT，SsHKT）和茄子中的甜瓜HKT（Solanum melongena HKT，SmHKT）的cDNA，并分析了它们在盐胁迫下不同组织中的表达。在根（28倍）和茎（7倍）中显著诱导SsHKT表达，Na+积累分别相应增加52%和29%。相反，茄子积累了60%的总Na+在叶片中，与较低的SmHKT表达水平在根（3倍）。越橘也保持了较高的K+/Na+比在叶片相比，茄子，由于其Na+浓度和K+浓度不变的减少。功能分析表明，SsHKT介导的Na+内流抑制酵母生长Na+胁迫下，和SsHKT没有补充K+摄取缺陷CY 162株K+限制条件下的生长。这些结果表明，这两种植物的Na+积累特性是由HKT基因的差异表达引起的，SsHKT发挥更大的控制能力的Na+到达叶片在越橘，比SmHKT在茄子。(C)2015 Elsevier Inc. All rights reserved.
Reduced Na+ accumulation in the leaf blade is an important aspect of salinity tolerance and high affinity K+ transporters (HKTs) are known to play a significant role in the process. Huckleberry and eggplant have previously been shown to display 'excluder' and Includer' characteristics, respectively, under salt stress, but the underlying mechanisms have not been investigated. Here, we isolated the cDNA of the HKT homologs, Solanum scabrum HKT (SsHKT) from huckleberry and Solanum melongena HKT (SmHKT) from eggplant, and analyzed their expressions in different tissues under salt stress. SsHKT expression was markedly induced in the root (28-fold) and stem (7-fold), with a corresponding increase in Na+ accumulation of 52% and 29%, respectively. Conversely, eggplant accumulated 60% total Na+ in the leaf blade, with a lower SmHKT expression level in the root (3-fold). Huckleberry also maintained a higher K+/Na+ ratio in the leaf blade compared to eggplant, due to the reduction of its Na+ concentration and unaltered K+ concentration. Functional analysis demonstrated that SsHKT-mediated Na+ influx inhibited yeast growth under Na+ stress, and that SsHKT did not complement the growth of the K+ uptake-deficient CY162 strain under K+-limiting conditions. These results suggest that the Na+ accumulation characteristics of both plants are caused by the differential expression of HKT genes, with SsHKT exerting a greater control over the ability of Na+ to reach the leaf blade in huckleberry, than SmHKT does in eggplant. (C) 2015 Elsevier Inc. All rights reserved.