Overexpression of PeHKT1;1 Improves Salt Tolerance in Populus.

Meng Xu,Ling Wu,Caihui Chen,Heng Cai

doi:10.3390/genes9100475

Abstract

Soil salinization is an increasingly serious threat that limits plant growth and development. Class I transporters of the high-affinity K+ transporter (HKT) family have been demonstrated to be involved in salt tolerance by contributing to Na+ exclusion from roots and shoots. Here, we isolated the PeHKT1;1 gene from hybrid poplar based on the sequences of the Populus trichocarpa genome. The full-length PeHKT1;1 gene was 2173 bp, including a 1608 bp open reading frame (ORF) encoding 535 amino acids and containing eight distinct transmembrane domains. Multiple sequence alignment and phylogenetic analysis suggested that the PeHKT1;1 protein had a typical S–G–G–G signature for the P-loop domains and belonged to class I of HKT transporters. PeHKT1;1 transcripts were mainly detected in stem and root, and were remarkably induced by salt stress treatment. In further characterization of its functions, overexpression of PeHKT1;1 in Populus davidiana × Populus bolleana resulted in a better relative growth rate in phenotypic analysis, including root and plant height, and exhibited higher catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities than non-transgenic poplar under salt stress conditions. These observations indicated that PeHKT1;1 may enhance salt tolerance by improving the efficiency of antioxidant systems. Together, these data suggest that PeHKT1;1 plays an important role in response to salt stress in Populus.

Highlights

In the natural environment, soil salinization is a major abiotic stress that limits plant growth and development
Excess salinity decreases water potential in plants, resulting in a reduced ability to take up water, and large amounts of sodium (Na+ ) and chloride (Cl− ) are taken up by the plant root system
“Nanlin895”) plants were cultivated on Murashige and Skoog (MS) medium supplemented with 0.2% (w/v) gelrite and 3.0% (w/v) sucrose in a humid chamber at a temperature of 25/18 ◦ C, daily photoperiod of 16/8 h, and relative humidity of 60–80%

Summary

Introduction

Soil salinization is a major abiotic stress that limits plant growth and development. High concentrations of salts in the soil have various adverse effects in plants, including osmotic stress and ion toxicity. Excess salinity decreases water potential in plants, resulting in a reduced ability to take up water, and large amounts of sodium (Na+ ) and chloride (Cl− ) are taken up by the plant root system. Excessive Na+ and Cl− within plants is toxic, and disturbs potassium (K+ ). To cope with soil salinization, plants have evolved diverse adaptive mechanisms, including Na+ exclusion from the shoot, Na+ expulsion from cell cytoplasm, and Na+. Na+ extrusion out of the cell and detoxification into vacuoles have been reported to be mediated by Salt-Overly-Sensitive 1 (SOS1) antiporters and

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Discussion

Conclusion