Functional characterization and expression study of sugarcane MYB transcription factor gene PEaMYBAS1 promoter from Erianthus arundinaceus that confers abiotic stress tolerance in tobacco

Sugarcane is a glycophyte which has to confront various biotic and abiotic stresses while standing in fields. These stresses ultimately affect the growth and sucrose contents, causing heavy losses to farmers. A genetic approach through transgenic technology offers promising avenues to counter stresses and overcome the losses in production. In this study, PEaMYBAS1 promoter from Erianthus arundinaceus, a wild relative of sugarcane, was isolated to reveal its stress tolerance mechanism at the transcriptional level. A series of PEaMYBAS1 promoter deletions constructed from the transcription start sites F1 (-161 bp), F2 (-282 bp), F3 (-554 bp), F4 (-598 bp), F5 (-714 bp), F6 (-841 bp), and F0 (-1032 bp) were fused to the uidA reporter gene (GUS) separately, and each construct was analyzed by agroinfiltration in tobacco leaves subjected independently to drought, cold, salinity and wounding. Deletion analysis of the PEaMYBAS1 promoter revealed that the F3 (-554 bp) region was required for basal expression. Interestingly, full length deletion fragment F0 (-1032 bp) showed the highest GUS activity in drought (4.9 fold), among the other abiotic stresses such as cold (3.89 fold), salinity (3.87 fold) and wounding (3.06 fold). GUS induction characterization of the promoter revealed the enhanced stress tolerance capacity against abiotic stresses in the model plant Nicotiana tabacum. Thus, the full length deletion fragment F0 (-1032) of the inducible promoter PEaMYBAS1 can be advocated as an important genetic engineering tool to develop stress tolerant plants.