Responses to flooding stress in soybean seedlings with the alcohol dehydrogenase transgene

The soybean is relatively sensitive to disturbances arising from flooding before its emergence from the soil. When young soybean seedlings at an early stage are transferred to flooding anaerobic conditions, alcohol dehydrogenase (Adh) mRNA and Adh protein increase temporarily in the root tips, where active cell division demands high energy production. Since there is little information on the significance of the up-regulation of Adh for the tolerance of soybeans to flooding stress, we examined the response to flooding in transgenic soybean lines in which the soybean Adh (GmAdh2) gene was introduced under the control of a constitutive promoter. Acquired transgenic soybean seeds from one out of 14 transgenic lines were subjected to flooding stress. Growth inhibition of soybean seedlings caused by flooding stress was reduced in soybeans with the GmAdh2 transgene. Protein analysis and enzyme assay at the early stage of growth of the soybean seedlings confirmed that Adh expressions and activities in transgenic soybeans were increased compared to control soybeans. These results indicated that the introduced GmAdh2 gene might have induced some change in glycolysis and alcohol fermentation, and improved the germination of transgenic soybeans under flooding stress.