Molecular Cloning and Functional Characterization of the Dehydrin (IpDHN) Gene From Ipomoea pes-caprae.

Hui Zhang,Jiexuan Zheng,Shuguang Jian,Huaxiang Su,Kuaifei Xia,Mei Zhang

doi:10.3389/fpls.2018.01454

Abstract

Dehydrin (DHN) genes can be rapidly induced to offset water deficit stresses in plants. Here, we reported on a dehydrin gene (IpDHN) related to salt tolerance isolated from Ipomoea pes-caprae L. (Convolvulaceae). The IpDHN protein shares a relatively high homology with Arabidopsis dehydrin ERD14 (At1g76180). IpDHN was shown to have a cytoplasmic localization pattern. Quantitative RT-PCR analyses indicated that IpDHN was differentially expressed in most organs of I. pes-caprae plants, and its expression level increased after salt, osmotic stress, oxidative stress, cold stress and ABA treatments. Analysis of the 974-bp promoter of IpDHN identified distinct cis-acting regulatory elements, including an MYB binding site (MBS), ABRE (ABA responding)-elements, Skn-1 motif, and TC-rich repeats. The induced expression of IpDHN in Escherichia coli indicated that IpDHN might be involved in salt, drought, osmotic, and oxidative stresses. We also generated transgenic Arabidopsis lines that over-expressed IpDHN. The transgenic Arabidopsis plants showed a significant enhancement in tolerance to salt/drought stresses, as well as less accumulation of hydrogen peroxide (H2O2) and the superoxide radical (O2−), accompanied by increasing activity of the antioxidant enzyme system in vivo. Under osmotic stresses, the overexpression of IpDHN in Arabidopsis can elevate the expression of ROS-related and stress-responsive genes and can improve the ROS-scavenging ability. Our results indicated that IpDHN is involved in cellular responses to salt and drought through a series of pleiotropic effects that are likely involved in ROS scavenging and therefore influence the physiological processes of microorganisms and plants exposed to many abiotic stresses.

Highlights

The halophyte Ipomoea pes-caprae L., belonging to the Convolvulaceae family, is mainly distributed in the littoral region of tropical and subtropical areas worldwide (Miryeganeh et al, 2014) and has attracted attention due to its sand fixation, wind resistance, landscape greening, and ecological restoration abilities in coral islands and coastal zones (Ouyang et al, 2011)
IpDHN and other candidate salt stress-related genes were identified from a complementary DNA (cDNA) full-length library, generated from total RNA of I. pes-caprae seedlings, based on the FOX gene hunting system, screened with a salt-sensitive yeast mutant strain, AXT3 (Zhou et al, 2015)
Our previous research indicated that the induced expression of IpDHN in yeast could partly rescue the salt-sensitive phenotype of the AXT3 yeast mutant and improved the salt tolerance of the wild type (WT) yeast W303

Summary

Introduction

The halophyte Ipomoea pes-caprae L., belonging to the Convolvulaceae family, is mainly distributed in the littoral region of tropical and subtropical areas worldwide (Miryeganeh et al, 2014) and has attracted attention due to its sand fixation, wind resistance, landscape greening, and ecological restoration abilities in coral islands and coastal zones (Ouyang et al, 2011). Throughout their whole life cycle, halophytes are subjected to abiotic stresses, including extreme salt damage, drought or dehydration, osmotic stress, and nutritional imbalance, depending on their habitats (Kumari et al, 2015). Further studies indicate that the K-segments are the functional core parts of DHNs that mediate cellular stress tolerance (Drira et al, 2013), bind to anionic phospholipid vesicles (Koag et al, 2009), or maintain enzyme activity (Yang et al, 2015)

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