Constitutive expression of the barley HvWRKY38 transcription factor enhances drought tolerance in turf and forage grass (Paspalum notatum Flugge)

WRKY proteins constitute a family of transcription factors involved in many plant processes, including responses to biotic and abiotic stress. A constitutive HvWRKY38 expression cassette was introduced into apomictic bahiagrass cultivar 'Argentine' by biolistic gene transfer. HvWRKY38 integration and expression was detected in transgenic bahiagrass plants and their apomictic seed progeny by Southern blot, PCR and quantitative real-time RT-PCR analysis, respectively. Transgenic and wildtype plants were grown hydroponically to allow uniform dehydration and rehydration treatments and measure whole plant relative water content and biomass. Transgenic bahiagrass plants retained water better during dehydration, recovered faster and produced more biomass following rehydration and survived severe dehydration stress under controlled environment conditions in contrast to non-transgenic plants. The observed dehydration tolerance is very desirable in perennial grasses like bahiagrass, where seasonal droughts affect establishment, persistence or productivity. Our results confirm the regulatory role of HvWRKY38 in dehydration tolerance.