Constitutive Expression of the Barley Dehydrin Gene aba2 Enhances Arabidopsis Germination in Response to Salt Stress

Cristina Calestani,Meena Moses,Elizabeth Bray,Nelson Marmiroli,Elena Maestri

doi:10.4081/pb.2015.5826

Abstract

Dehydrins (DHNs) are a sub-family of the late embryogenesis abundant proteins generally induced during development of desiccation tolerance in seeds and water deficit or salinity stress in plants. Nevertheless, a detailed understanding of the DHNs function is still lacking. In this work we investigated the possible protective role during salt stress of a Dhn from Hordeum vulgare (L.), aba2. The coding sequence of the aba2 gene was constitutively expressed in transgenic lines of Arabidopsis thaliana (L.). During salt stress conditions germination rate, cotyledon expansion and greening were greatly improved in the transgenic lines as compared to the wild type. Between 98 and 100% of the transgenic seeds germinated after two weeks in media containing up to 250 mM NaCl, and 90% after 22 days at 300 mM NaCl. In conditions of 200 mM NaCl 93% of the transgenic cotyledons had greened after two weeks, outperforming the wild type by 45%. Our study provides further evidence that DHNs have an important role in salt stress tolerance. The production of plants constitutively expressing DHNs could be an effective strategy to improve plant breeding programs.

Highlights

Salinity stress can impact plant growth and development at all stages of the plant life cycle.Plants respond to abiotic stress in many ways that are controlled by complex regulatory processes functioning at cellular and wholeplant levels, which are still not completely understood
The Dhn gene used in this study, aba[2], maps on the long arm of chromosome 5H of barley within a major QTL controlling freezing tolerance,[32,33] on the 5AL chromosome of wheat within the confidence interval of a QTL associated with abscissic acid (ABA)
In this work we investigated the biological function of a Dhn from Hordeum vulgare (L.), aba[2] (National Center for Biotechnology Information accession number CAA66970), and its possible protective role during salt stress

Summary

Introduction

Salinity stress can impact plant growth and development at all stages of the plant life cycle. Dhn[1] and it codes for a protein with a molecular mass of 22 kDa.[1,7] We tested germination, cotyledon expansion and greening, and seedling growth on medium containing NaCl concentrations that were restrictive to the Arabidopsis control plants. Four-week-old plants were transformed by vacuum infiltration of A. tumefaciens carrying the pCGN18A2 plasmid.[40] Seeds produced by the infiltrated plants (T1 generation) were surface sterilized and sown in Petri dishes on solid Murashige and Skoog (MS) medium,[41] containing 50 μg/mL-1 of kanamycin. The Petri dishes with Arabidopsis DHNs amino acid sequences, the membrane (Micron Separations, Westborough, the seeds were incubated for 3 days at 4°C in barley ABA2/DHN1, the wheat DHN5 and the MA, USA) with Mini Trans-Blot Cells The estimated mean time to germination differences between the wild type (C) and

Results

Germination and seedling growth analyses in response to salt stress

Seed germination on media containing

Another possible role of DHNs may be the

Overexpression of the acidic dehydrin