Abiotic stress tolerance in transgenic eggplant (Solanum melongena L.) by introduction of bacterial mannitol phosphodehydrogenase gene

In the present work, the bacterial mannitol-1-phosphodehydrogenase (mtlD) gene was introduced into eggplant (Solanum melongena L.) by Agrobacterium tumefaciens-mediated transformation. Several transformants were generated and the transgene integration was confirmed by PCR, dot blot and Southern blot analysis. Transgenic lines of T-0 and T-1 generations were examined for tolerance to NaCl-induced salt stress, polyethylene glycol-mediated drought and chilling stress under both in vitro and in vivo growth conditions. A considerable proportions of transgenic seeds germinated and seedlings grew well on 200 mM salt-amended MS basal medium, whereas seeds of untransformed control plants failed to germinate. Further, leaf explants from the transgenics could grow and showed signs of shoot regeneration on salt-amended MS regeneration medium, whereas wild type did not respond, and in fact the explants showed necrosis and loss of chlorophyll after about one week. The transgenic leaves could also withstand desiccation, and transgenics could grow well under chilling stress, and hydroponic conditions with salt stress as compared to wild type plants. Thus, the transgenic lines were found to be tolerant against osmotic stress induced by salt, drought and chilling stress. The morphology of the transgenic plants was normal as controls, but the chlorophyll content was higher in some of the lines. These observations suggest that mtlD gene can impart abiotic stress tolerance in eggplant.