Introgression of the SbASR-1 gene cloned from a halophyte Salicornia brachiate enhances salinity and drought endurance in transgenic groundnut (arachis hypogaea)and acts as a transcription factor [corrected

Vivekanand Tiwari,Amit Kumar Chaturvedi,Avinash Mishra,Bhavanath Jha,Prabodh Kumar Trivedi

doi:10.1371/journal.pone.0131567

Vivekanand Tiwari, Amit Kumar Chaturvedi + Show 3 more

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https://doi.org/10.1371/journal.pone.0131567

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Journal: PloS one	Publication Date: Jul 9, 2015
Citations: 82	License type: CC BY 4.0

Affiliation: Central Salt and Marine Chemicals Research Institute

Abstract

The SbASR-1 gene, cloned from a halophyte Salicornia brachiata, encodes a plant-specific hydrophilic and stress responsive protein. The genome of S. brachiata has two paralogs of the SbASR-1 gene (2549 bp), which is comprised of a single intron of 1611 bp, the largest intron of the abscisic acid stress ripening [ASR] gene family yet reported. In silico analysis of the 843-bp putative promoter revealed the presence of ABA, biotic stress, dehydration, phytohormone, salinity, and sugar responsive cis-regulatory motifs. The SbASR-1 protein belongs to Group 7 LEA protein family with different amino acid composition compared to their glycophytic homologs. Bipartite Nuclear Localization Signal (NLS) was found on the C-terminal end of protein and localization study confirmed that SbASR-1 is a nuclear protein. Furthermore, transgenic groundnut (Arachis hypogaea) plants over-expressing the SbASR-1 gene constitutively showed enhanced salinity and drought stress tolerance in the T1 generation. Leaves of transgenic lines exhibited higher chlorophyll and relative water contents and lower electrolyte leakage, malondialdehyde content, proline, sugars, and starch accumulation under stress treatments than wild-type (Wt) plants. Also, lower accumulation of H2O2 and O2 .- radicals was detected in transgenic lines compared to Wt plants under stress conditions. Transcript expression of APX (ascorbate peroxidase) and CAT (catalase) genes were higher in Wt plants, whereas the SOD (superoxide dismutase) transcripts were higher in transgenic lines under stress. Electrophoretic mobility shift assay (EMSA) confirmed that the SbASR-1 protein binds at the consensus sequence (C/G/A)(G/T)CC(C/G)(C/G/A)(A/T). Based on results of the present study, it may be concluded that SbASR-1 enhances the salinity and drought stress tolerance in transgenic groundnut by functioning as a LEA (late embryogenesis abundant) protein and a transcription factor.

Highlights

Abscisic acid stress ripening-1 (ASR-1) genes are stress and developmentally regulated plantspecific genes, first reported in tomato [1]
The present study showed higher MDA content and electrolyte leakage in Wt plants than SbASR-1-overexpressing transgenic lines under both salinity and drought stress conditions (Fig 8B and 8C)
The SbASR-1 protein has a number of disorder promoting amino acids, glycine residues and N-myristoylation sites, which enable its function more efficiently compared to glycophytic ASR-1 proteins

Summary

Introduction

Abscisic acid stress ripening-1 (ASR-1) genes are stress and developmentally regulated plantspecific genes, first reported in tomato [1]. There are a number of paralogs of the ASR gene family in different plant groups [2]. ASR-1 gene transcript expression has been reported to be induced by several abiotic and biotic factors [4]. Overexpression of ASR-1 genes in different plant species showed increased tolerance to oxidative, salinity and dehydration stress [12,13,14]. These reports suggest that ASR-1 genes are potential candidates for genetic engineering of crops for better stress tolerance

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