Abstract
Osmotins are multifunctional proteins belonging to the thaumatin-like family related to plant stress responses. To better understand the functions of soybean osmotins in drought stress response, the current study presents the characterisation of four previously described proteins and a novel putative soybean osmotin (GmOLPa-like). Gene and protein structure as well as gene expression analyses were conducted on different tissues and developmental stages of two soybean cultivars with varying dehydration sensitivities (BR16 and EMB48 are highly and slightly sensitive, respectively). The analysed osmotin sequences share the conserved amino acid signature and 3D structure of the thaumatin-like family. Some differences were observed in the conserved regions of protein sequences and in the electrostatic surface potential. P21-like present the most similar electrostatic potential to osmotins previously characterised as promoters of drought tolerance in Nicotiana tabacum and Solanum nigrum. Gene expression analysis indicated that soybean osmotins were differentially expressed in different organs (leaves and roots), developmental stages (R1 and V3), and cultivars in response to dehydration. In addition, under dehydration conditions, the highest level of gene expression was detected for GmOLPa-like and P21-like osmotins in the leaves and roots, respectively, of the less drought sensitive cultivar. Altogether, the results suggest an involvement of these genes in drought stress tolerance.
Highlights
Due to plants being sessile organisms, they are often exposed to various abiotic stresses such as drought, cold, and soil salinity
A phylogenetic tree reconstructed with the remaining thaumatin-like sequences allowed the identification of an osmotin monophyletic clade including the eight previously identified osmotins from N. tabacum, S. nigrum, G. max
Various osmotin proteins have been identified from a variety of plants and characterised based on their potential subcellular location, pI value, and gene expression in response to biotic and abiotic stresses (Tachi et al, 2009; Chowdhury et al, 2015; Ullah et al, 2017)
Summary
Due to plants being sessile organisms, they are often exposed to various abiotic stresses such as drought, cold, and soil salinity These environmental stresses result in osmotic changes that can lead to the disruption of normal cellular activities, affecting plant growth and development. Osmotins were first isolated and characterised in tobacco cells adapted to a low osmotic potential, and have been induced in several plant species - including Glycine max (soybean) - in response to various abiotic and biotic stresses (Parkhi et al, 2009; Weber et al, 2014).
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