Heterologous expression of SbAP 37-transcription factor in Sesamum indicum L. alleviates salt stress and improves antioxidant enzyme activities

Deembryonated cotyledons of Sesame ( Sesamum indicum L.), an oil yielding crop plant, were transformed using Agrobacterium tumefaciens strain LBA4404 with the binary vector pCAMBIA 1301, having hygromycin resistance gene ( hpt II) as a selectable marker and β-glucuronidase ( GUS ) as a reporter and Sb APETALA37 ( SbAP37 ) transcription factor (isolated from Sorghum bicolor ) under the influence of the stress inducible promoter abscisic acid2 ( ABA2 ) for salt stress tolerance (isolated from indica rice). Deembryonated cotyledons proved better explants compared to hypocotyls for shoot regeneration (data not shown). Green shoots were recovered from transformed explants on the Murashige and Skoog’s (MS) medium supplemented with 5 mg L −1 6-benzylaminopurine (BAP) + 1 mg L −1 indole-3-acetic acid + 1 mg L −1 ABA + 5 mg L −1 silver nitrate (AgNO 3 ) + 5 mg L −1 hygromycin. Shoots (3–4 cm long) were transferred onto MS medium fortified with 3 mg L −1 indole-3-butyric acid and 5 mg L −1 hygromycin for rooting. Integration of the SbAP37 and hptII genes was confirmed by amplifying them using polymerase chain reaction (PCR). Transgenic plants accumulated 2 to 3-folds higher proline under 150 mM NaCl stress when compared to untransformed control plants. Transgenic plants exhibited higher chlorophyll than the untransformed controls. While malondialdehye (MDA) levels were low, peroxidase (POX), superoxide dismutase (SOD) and catalase (CAT) activities were 2–3-folds higher in transgenics under NaCl stress. This work possibly paves the way for exploiting other candidate genes for engineering salt, drought and biotic stress tolerance in the recalcitrant and neglected orphan crop sesame.