Overexpression of a samphire high-affinity potassium transporter gene SbHKT enhances salt stress tolerance in transgenic cotton

Cotton (Gossypium hirsutum L.) is an important commercial crop that is grown worldwide as a source of fiber and edible oil. Cotton shows higher drought and salt tolerance than do many other major crops such as rice, wheat, and maize. Even so, abiotic stress still have a significant effect on the growth and yield of cotton, which makes it difficult in improvement of salt tolerance in upland cotton. Therefore, the mining of some stress resistance genes will provide potential candidate genes for transgenic resistance breeding in cotton. Some salt stress-related gene high-affinity potassium transporter play an important role in plant salt resistance pathway. Meanwhile, a putative high-affinity potassium transporter gene SbHKT was isolated from halophyte Salicornia bigelovii by RACE cloning in an earlier research. We conducted a preliminary functional analysis by transferring the gene into tobacco and cotton with agrobacterium-mediated transgenic technology. By the use of Agrobacterium tumefaciens high-affinity K+ SbHKT gene was transferred into tobacco, and resistance plants were screened. By PCR detection of T0 generation regenerated plants, transgenic tobacco plants were successfully expressed at the mRNA level. Identification salt tolerance of transgenic tobacco indicated the transgenic plants were more resistant to the salt tolerant. SbHKT gene was transportered into cotton, and southern blot analysis of positive plants shows the gene SbHKT has been integrated into the cotton genome. Tissue-specifc expression showed that SbHKT is expressed at differential levels in all tissues examined and strongly induced by various phytohormones and abiotic stress. In vivo and in vitro subcellular localization suggested that SbHKT is located in the plasmamembrane. In response to salt stress, transgenic cotton plants overexpressing SbHKT showed signifcantly higher germination rates, longer roots, and more vigorous growth than wild-type plants. These findings demonstrated that SbHKT plays an important role in the abiotic stress response, and that overexpression of SbHKT in transgenic cotton improves salt tolerance.