Overexpression of a Chimeric Gene, OsDST-SRDX, Improved Salt Tolerance of Perennial Ryegrass.

Huifang Cen,Wenxing Ye,Kexin Wang,Dayong Li,Wanjun Zhang,Yanrong Liu

doi:10.1038/srep27320

Abstract

The Drought and Salt Tolerance gene (DST) encodes a C2H2 zinc finger transcription factor, which negatively regulates salt tolerance in rice (Oryza sativa). Phylogenetic analysis of six homologues of DST genes in different plant species revealed that DST genes were conserved evolutionarily. Here, the rice DST gene was linked to an SRDX domain for gene expression repression based on the Chimeric REpressor gene-Silencing Technology (CRES-T) to make a chimeric gene (OsDST-SRDX) construct and introduced into perennial ryegrass by Agrobacterium-mediated transformation. Integration and expression of the OsDST-SRDX in transgenic plants were tested by PCR and RT-PCR, respectively. Transgenic lines overexpressing the OsDST-SRDX fusion gene showed obvious phenotypic differences and clear resistance to salt-shock and to continuous salt stresses compared to non-transgenic plants. Physiological analyses including relative leaf water content, electrolyte leakage, proline content, malondialdehyde (MDA) content, H2O2 content and sodium and potassium accumulation indicated that the OsDST-SRDX fusion gene enhanced salt tolerance in transgenic perennial ryegrass by altering a wide range of physiological responses. To our best knowledge this study is the first report of utilizing Chimeric Repressor gene-Silencing Technology (CRES-T) in turfgrass and forage species for salt-tolerance improvement.

Highlights

The area of saline land worldwide is nearly 1 billion hectares, and accounts for 10 percent of the total land area[1,2]
A Neighbor-Joining phylogenetic tree of six Drought and Salt Tolerance (DST) derived from different plant species (Hordeum vulgare, Panicum virgatum, Oryza sativa, Brachypodium distachyon, Setaria italic and Zea mays) was constructed, which demonstrated that the DST gene was conserved evolutionarily in C3 and C4 plants (Fig. 1A)
The sequence identity between the conserved nucleotide fragments between the DSTs indicated that the DST gene existed in the genome of perennial ryegrass and might be related to the drought and salt tolerance of perennial ryegrass

Summary

Introduction

The area of saline land worldwide is nearly 1 billion hectares, and accounts for 10 percent of the total land area[1,2]. Perennial ryegrass (Lolium perenne L.) is an important cool-season grass in temperate regions worldwide It is widely cultivated as a turfgrass and forage with favorable agronomic traits, including rapid establishment rate, strong tiller ability, strong trample resistance, as well as high yield[3]. Breeding new varieties of perennial ryegrass with enhanced salt tolerance through genetic engineering is expected[3,4]. A growing number of reports focused on model plants and crops have indicated that salt tolerance could be improved by genetic transformation[4,16,17]. Overexpression of genes related to the Na+/H+ antiporter significantly improved the salt resistance of transgenic plants. Overexpression of a rice vacuolar Na+/H+ antiporter gene, OsNHX1, in perennial ryegrass significantly increased the salt resistance of transgenic plants[12]. The DCA1-DST-Prx[24] pathway contributed to drought and salt tolerance in rice

Methods

Results

Conclusion