Incorporation of Na⁺/H⁺ antiporter gene from <i style="mso-bidi-font-style:normal">Aeluropus littoralis </i>confers salt tolerance in soybean (<i style="mso-bidi-font-style:normal">Glycine max</i> L.)

Abstract

To develop a salt-tolerant soybean (<i style="mso-bidi-font-style:normal">Glycine max</i> L.) cultivar, a minimal linear Na⁺/H⁺ antiporter gene cassette (35S CaMV promoter, open-reading-frame of <i style="mso-bidi-font-style:normal">AlNHX1</i> from <i style="mso-bidi-font-style:normal">Aeluropus littoralis</i> and NOS terminator) was successfully expressed in soybean cultivar TF-29. Southern and Northern blot analysis showed that <i style="mso-bidi-font-style:normal">AlNHX</i><i style="mso-bidi-font-style:normal">1</i> was successfully incorporated into the genome and expressed in the transgenic plants. The <i style="mso-bidi-font-style: normal">AlNHX1</i> transgenic plant lines exhibited improved growth in severe saline condition (150 mM NaCl). The transgenic lines accumulated a lower level of Na⁺ and a higher level of K⁺ in the leaves than wild-type plants under saline condition (150 mM NaCl). Observations on the chlorophyll content, photosynthetic rates, malondialdehyde and relative electrical conductivity indicated that transgenic plants exhibited tolerance to salt stress, growing normally at salt concentrations up to 150 mM. These results demonstrated that <i style="mso-bidi-font-style:normal">AlNHX1</i> was successfully transferred into soybean and the salt-tolerance was improved by the overexpression of <i style="mso-bidi-font-style:normal">AlNHX1</i>.