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KMID : 0368420090520020147
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Journal of Plant Biology
2009 Volume.52 No. 2 p.147 ~ p.147
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Salt Tolerance is Conferred in Arabidopsis by Overexpression of the Vacuolar Na (+)/H (+) Antiporter Gene SsNHX2, an Alternative Splicing Variant of SsNHX1, from Suaeda salsa
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Li Weihuan
Zhang Quan
Kong Xiangqiang
Wu Chunxia
Ma Xiuling
Zhao Yanxiu
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Abstract
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Vacuolar Na+/H+ antiporters catalyze the exchange of Na+ for H+ across vacuolar membranes and compartmentalize Na+ into vacuoles. They play important roles in cellular pH and Na+ homeostasis. The SsNHX1 gene was previously cloned from a typical euhalophyte, Suaeda salsa. Its cloning revealed another N-terminus truncated transcript, SsNHX2. This potentially alternative splicing variant was truncated from the 49 amino acid residues (aa) of the N terminus of SsNHX1. To compare their degree of salt tolerance, we over-expressed SsNHX1 and SsNHX2 in Arabidopsis. Southern and northern blot analyses showed that both genes had been integrated into that genome and had expressed in several lines. Two types of transgenic plants grew more vigorously than the wild type (WT) under salt stress, but no remarkable differences were found between those SsNHX1 and SsNHX2 transformants. Physiological analyses also supported this phenotype. Both fresh and dry weights of the transgenics as well as their accumulations of Na+ and K+ under salinity were much higher than that of WT, but differences were not significant between SsNHX1 and SsNHX2 plants for any of those parameters. These results suggest that SsNHX2 is a functional Na+/H+ antiporter like SsNHX1 and their levels of salt tolerance are similar.
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KEYWORD
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Alternative splicing, Overexpression, Salt tolerance, SsNHX1, SsNHX2, Suaeda salsa, Vacuolar Na+/H+ antiporter
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