Molecular cloning and characterization of drought stress responsive abscisic acid-stress-ripening (Asr1) gene from wild jujube, Ziziphus nummularia (Burm.f.) Wight & Arn

Abstract

Drought is a calamitous abiotic stress hampering agricultural productivity all over the world and its severity is likely to increase further.
Abscisic acidstressripening
proteins (ASR), are a group of small hydrophilic proteins which are induced by abscisic acid, stress and
ripening in many plants. In the present study, ZnAsr 1 gene was fully characterized for the first time from Ziziphus nummularia, which is
one of the most low water forbearing plant. Full length ZnAsr 1 gene was characterised and in silico analysis of ZnASR1 protein was
done for predicting its phylogeny and physiochemical properties. To validate transcriptional pattern of ZnAsr 1 in response to drought
stress, expression profiling in polyethylene glycol (PEG) induced Z. nummularia seedlings was studied by RTqPCR
analysis and
heterologous expression of the recombinant ZnAsr1 in Escherichia coli. The nucleotide sequence analysis revealed that the complete
open reading frame of ZnAsr 1 is 819 bp long encoding a protein of 273 amino acid residues, consisting of a histidine rich N terminus
with an abscisic acid/water deficit stress domain and a nuclear targeting signal at the C terminus. In expression studies, ZnAsr 1 gene
was found to be highly upregulated under drought stress and recombinant clones of E. coli cells expressing ZnASR1 protein showed
better survival in PEG containing media. ZnAsr1 was proven to enhance drought stress tolerance in the recombinant E.coli cells
expressing ZnASR1. The cloned ZnAsr1 after proper validation in a plant system, can be used to develop drought tolerant transgenic
crops