Expression of Pennisetum glaucum Eukaryotic Translational Initiation Factor 4A (PgeIF4A) Confers Improved Drought, Salinity, and Oxidative Stress Tolerance in Groundnut

Abstract

Eukaryotic translational initiation factor 4A belong to family of helicases, involved in multifunctional activities during stress and non-stress conditions. The <i>eIF4A</i> gene was isolated and cloned from semi-arid cereal crop of <i>Pennisetum glaucum</i>. In present study, the <i>PgeIF4A</i> gene was expressed under the regulation of stress inducible <i>Arabidopsis rd29A</i> promoter in groundnut (<i>cv</i> JL-24) with <i>bar</i> as a selectable marker. The de-embryonated cotyledons were infected with <i>Agrobacterium tumefaciens</i> (LBA4404) carrying <i>rd29A:PgeIF4A</i> construct and generated high frequency of multiple shoots in phosphinothricin medium. Twenty- four T₀ plants showed integration of both <i>nos-bar</i> and <i>rd29A-PgeIF4A</i> gene cassettes in genome with expected amplification products of 429 and 654 bps, respectively. Transgene copy number integration was observed in five T₀ transgenic plants through Southern blot analysis. Predicted Mendelian ratio of segregation (3:1) was noted in transgenic plants at T₁ generation. The T₂ homozygous lines (L1-5, L8-2, and L16-2) expressing <i>PgeIF4A</i> gene were exhibited superior growth performance with respect to phenotypic parameters like shoot length, tap root length, and lateral root formation under simulated drought and salinity stresses compared to the wild type. In addition, the chlorophyll retention was found to be higher in these plants compared to the control plants. The quantitative real time-PCR results confirmed higher expression of <i>PgeIF4A</i> gene in L1-5, L8-3, and L16-2 plants imposed with drought/salt stress. Further, the salt stress tolerance was associated with increase in oxidative stress markers, such as superoxide dismutase accumulation, reactive oxygen species scavenging, and membrane stability in transgenic plants. Taken together our results confirmed that the <i>PgeIF4A</i> gene expressing transgenic groundnut plants exhibited better adaptation to stress conditions.