Ectopic overexpression of a salt stress-induced pathogenesis - related class 10 protein ( PR10 ) gene from peanut ( Arachis hypogaea L.) affords broad spectrum abiotic stress tolerance in transgenic tobacco

Pathogenesis-related proteins are induced in plants in response to stress, pathogen attack or abiotic stimuli, thus playing a cardinal role in plant defense system. A cDNA containing the full-length ORF, AhSIPR10 (474 bp, GenBank acc. no. DQ813661), encoding a novel Salinity-Induced PR class 10 protein was isolated from callus cell lines of peanut (Arachis hypogaea). Real-time quantitative reverse transcription PCR (qRT–PCR) data showed rapid upregulation of AhSIPR10 transcription in peanut callus cultures across salinity, heavy metal, cold and mannitol-induced drought stress environments. Likewise, AhSIPR10 expression was also responsive towards defense/stress signaling molecules salicylic acid (SA), methyl jasmonate, abscisic acid (ABA) and H2O2 treatments. Methyl jasmonate or ABA-induced AhSIPR10 expression was, however, antagonized by SA treatment. A functional role of AhSIPR10 in alleviation of abiotic stress tolerance was further validated through its over-expression in tobacco. Analysis of T1 transgenic tobacco plants overexpressing AhSIPR10 gene showed enhanced tolerance to salt, heavy metal and drought stress through leaf disc senescence, chlorophyll content, seed set and germination assays, thus corroborating a role of salt inducible-PR10 protein in mitigation of abiotic stress-induced damage. Transgenic tobacco lines overexpressing AhSIPR10 displayed adequate photosynthetic CO2 assimilation rates under salt, heavy metal and drought stress environments.