Mannitol-accumulating transgenic eggplants exhibit enhanced resistance to fungal wilts

Earlier, we have reported that the transgenic eggplants containing E. coli mannitol-1-phosphate dehydrogenase (mtlD) gene showed increased tolerance to abiotic stresses [V. Prabhavathi, J.S. Yadav, P.A. Kumar, M.V. Rajam, Abiotic stress tolerance in transgenic eggplant (Solanum melongena L.) by introduction of bacterial mannitol phosphate dehydrogenase gene, Mol. Breed. 9 (2002) 137-147]. We now show that such transgenics expressing mtlD gene with mannitol accumulation exhibit increased resistance against three fungal wilts caused by Fusarium oxysporum, Verticillium dahliae and Rhizoctonia solani under both in vitro and in vivo growth conditions. Mannitol levels could not be detected in the wild-type plants, but the presence of mannitol in the transgenics could be positively correlated with the disease resistance. These results and the previous data suggest that mtlD gene can be used for engineering crop plants for both biotic and abiotic stress tolerance.