Overexpression of expansin EaEXPA1, a cell wall loosening protein enhances drought tolerance in sugarcane

Sugarcane (Saccharum spp. hybrid) contributes to 80% of world sugar production and is a valuable source of biomass for the production of lignocellulosic ethanol making it an important commercial crop. Drought stress is one of the major abiotic stress factors which reduces the productivity and quality of sugarcane. Increase in the intensity and duration of drought coupled with the rising demand of sugar warrants the development of drought-tolerant sugarcane. Genetic engineering offers potential strategies to develop superior sugarcane varieties that improve crop productivity in drought-prone environments. Thus, with a view to develop drought-tolerant sugarcane, in the present study, an expansin gene which confers drought tolerance, was transformed into sugarcane. An expansin gene (EaEXPA1) from Erianthus arundinaceus, a wild relative of sugarcane, was overexpressed in the commercial sugarcane variety Co 86032 through Agrobacterium-mediated transformation. Transgenic lines exhibited significantly higher level of EaEXPA1 expression over the control plants. The performance evaluation of V1 transgenics under the drought stress revealed significantly higher relative water content, cell membrane thermostability, chlorophyll content, photosynthetic efficiency (Fv/Fm) and gas-exchange parameters than untransformed control plants. Here, it is reported for the first time that the overexpression of EaEXPA1 in sugarcane enhances drought tolerance. Thus, EaEXPA1 can be a potential target gene for improving drought tolerance in sugarcane.