Improving Water Use Efficiency in Switchgrass (Panium virgatum) By Overexpression of the AtLOV1 Gene.

Switchgrass (Panium virgatum L.) is one of the most promising energy crops dedicated for large scale biomass feedstock production. Drought stress is one of the major limiting factors for switchgrass growth in many regions. Transgenic switchgrass plants with overexpression of an Arabidopsis NAC transcriptional factor gene, LONG VEGETATIVE PHASE ONE (AtLOV1), has an erect leaf phenotype and altered lignin content in cell wall biomass. This study was to investigate physiological and metabolic responses of AtLOV1 transgenic switchgrass plants to drought stress.  Twelve lines either with or without the AtLOV1 transgene were clonal replicated and divided into two groups. Tested plants were transplanted into and grown in pots filled with soil and sand (2:1, v/v) mixture for two months, and then subjected to drought stress treatment for 30 days. A randomized block design was used with three replications. Under drought stress conditions, the AtLOV1 transgenic plants had higher leaf relative water content, lower electrolyte leakage, higher photosynthetic rate, and water use efficiency relative to the non-transgenic lines.  In addition, the AtLOV1 transgenic plants have higher raffinose content than the non-transgenic lines.  The results suggest that switchgrass water use efficiency and drought tolerance could be improved by overexpression of AtLOV1 gene.