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KMID : 0368420170600030259
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Journal of Plant Biology
2017 Volume.60 No. 3 p.259 ~ p.267
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The K+/H+ antiporter AhNHX1 improved tobacco tolerance to NaCl stress by enhancing K+ retention
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Zhang Wei-Wei
Meng Jing-Jing
Xing Jin-Yi
Yang Sha
Guo Feng
Li Xin-Guo
Wan Shu-Bo
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Abstract
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High salinity is the one of important factors limiting plant growth and crop production. Many NHX-type antiporters have been reported to catalyze K+/H+ exchange to mediate salt stress. This study shows that an NHX gene from Arachis hypogaea L. has an important role in K+ uptake and transport, which affects K+ accumulation and plant salt tolerance. When overexpressing AhNHX1, the growth of tobacco seedlings is improved with longer roots and a higher fresh weight than the wild type (WT) under NaCl treatment. Meanwhile, when exposed to NaCl stress, the transgenic seedlings had higher K+/H+ antiporter activity and their roots got more K+ uptake. NaCl stress could induce higher K+ accumulation in the roots, stems, and leaves of transgenic tobacco seedlings but not Na+ accumulation, thus, leading to a higher K+/Na+ ratio in the transgenic seedlings. Additionally, the AKT1, HAK1, SKOR, and KEA genes, which are involved in K+ uptake or transport, were induced by NaCl stress and kept higher expression levels in transgenic seedlings than in WT seedlings. The H+-ATPase and H+-PPase activities were also higher in transgenic seedlings than in the WT seedlings under NaCl stress. Simultaneously, overexpression of AhNHX1 increased the relative distribution of K+ in the aerial parts of the seedlings under NaCl stress. These results showed that AhNHX1 catalyzed the K+/H+ antiporter and enhanced tobacco tolerance to salt stress by increasing K+ uptake and transport.
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KEYWORD
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Arachis hypogaea L., K+/H+ Antiporter, K+ transport, K+ uptake, Salt stress
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