Cloning and characterization of Na+/H+ antiporter (LfNHX1) gene from a halophyte grass Leptochloa fusca for drought and salt tolerance

Abstract

Abiotic stresses such as salinity and drought have adverse effects on plants. In the present study, a Na(+)/H(+) antiporter gene homologue (LfNHX1) has been cloned from a local halophyte grass (Leptochloa fusca). The LfNHX1 cDNA contains an open reading frame of 1,623 bp that encodes a polypeptide chain of 540 amino acid residues. LfNHX1 protein sequence showed high similarity with NHX1 homologs reported from other halophyte plants. Amino acid and nucleotide sequence similarity, protein topology modeling and the presence of conserved functional domains in the LfNHX1 protein sequence classified it as a vacuolar NHX1 homolog. The overexpression of LfNHX1 gene under CaMV35S promoter conferred salt and drought tolerance in tobacco plants. Under drought stress, transgenic plants showed higher relative water contents, photosynthetic rate, stomatal conductance and membrane stability index as compared to wild type plants. More negative value of leaf osmotic potential was also observed in transgenic plants when compared with wild type control plants. Transgenic plants showed better germination and root growth at 2 mg L(-1) Basta herbicide and three levels (100, 200 and 250 mM) of sodium chloride. These results showed that LfNHX1 is a potential candidate gene for enhancing drought and salt tolerance in crops.

RNA-Seq analysis of Clerodendrum inerme (L.) roots in response to salt stress

“…The salt tolerance of a halophyte is determined by effective coordination between various physiological processes, metabolic pathways and gene networks under salt stress, including activation of antioxidant enzymes, induction and modulation of plant hormones, biosynthesis of compatible solutes and osmoprotectants, selective accumulation, exclusion of ions, and other mechanisms [15][16][17][18]. Furthermore, numerous genes that were isolated from halophytes have also been exploited by various modern biotechnological techniques to identify the genes that function in salt tolerance, including genes encoding for transcription factors [19,20], the Na + /H + antiporter gene [21,22] and genes encoding antioxidant enzymes [23,24]. The existence of these genes enhances the tolerance of plants to salt and provides more choices for the improvement of salt tolerance in crops.…”

ISOLATION AND SEQUENCE ANALYSIS OF A NOVEL PARTIAL VACUOLAR Na+/H+ ANTIPORTER cDNA FROM Capparis orientalis, Lycium shawii AND Zygophyllum album

“…Plant tolerance to salt stress is a multigenic trait and requires the coordinated action of several gene, but it is evident from several reports that overexpression of a single gene can also improve salt tolerance in plants (Apse et al, 1999;Gaxiola et al, 1999;Zhang and Blumwald, 2001;Li et al, 2003;Ma et al, 2004;Zorb et al, 2005;Li et al, 2008;Wu et al, 2009;Tang et al, 2010;Guan et al, 2011;Wu et al, 2011;Liu et al, 2012, andRauf et al, 2014). Isolating RNA using both the commercial reagent TRIzol ® Reagent (Invitrogen) followed by purification step with a Qiagen spin-column and RNeasy plant mini Kit (Qiagen) purified with PEG for RNA extraction showed high efficiency for isolating high-quality and quantity RNA suitable for using in sensitive downstream applications.…”

“…The vacuolar Na + /H + antiporter is a transmembrane protein which can catalyze the exchange of Na + and H + across the vacuolar membrane and maintains cellular pH and Na + homeostasis in plants (Apse et I al., 1999;. Recently many genes encoding vacuolar Na + /H + antiporters (NHX1) have been characterized and isolated from several plant species such as: Arabidopsis thaliana (Apse et al, 1999;Gaxiola et al, 1999), tomato (Zhang and Blumwald, 2001), Brassica napus (Wang et al, 2003), Atriplex dimorphostegia (Li et al, 2003), Suaeda salsa (Ma et al, 2004), Zea mays (Zorb et al, 2005), Chenopodium glaucum (Li et al, 2008), Thellungiella halophila (Wu et al, 2009), Trifolium repens (L.) (Tang et al, 2010), Zygophyllum xanthoxylum (Wu et al, 2011), Halostachys caspica (Guan et al, 2011), Karelinia caspica (Liu et al, 2012) and Leptochloa fusca (Rauf et al, 2014).…”

Advances in salt tolerance molecular mechanism in tobacco plants

“…LfNHX1 protein sequence showed high similarity with NHX1 homologs reported from other halophyte plants. The overexpression of LfNHX1 gene under CaMV35S promoter conferred salt and drought tolerance in tobacco plants [41,42]. NbNHX1 silencing led to a lower pH in the vacuole and a lower cellular ROS level in N. benthamiana, which was coupled with a decreased NAD(P) (H) pool and decreased expression of ROSresponsive genes [43].…”