Over-Expression of Arabidopsis DREB1A Gene in Transgenic Poa Pratensis Impacts on Osmotic Adjustment and Hormone Metabolism Under Drought

Drought stress is a major limiting factor in turfgrass management in many regions. The objective of this study was to examine responses of transgenic Kentucky bluegrass (Poa pratensis L.) overexpressing an Arabidopsis DREB1A gene to drought stress. Five transgenic Kentucky bluegrass (cv. Baron) lines overexpressing AtDREB1A and wild-type (WT, nontransgenic plant) were subjected to water deficit for 12 d and then rewatering treatment for 3 d. Leaf relative water content (RWC), turf quality, electrolyte leakage (EL), osmoregulating compounds, abscisic acid (ABA), and indol-3-acetic acid (IAA) content were measured. Transgenic plants had higher RWC and turf quality and lower EL relative to WT plants during drought stress and recovery periods. In addition, the transgenic plants had greater osmotic adjustment associated with higher water-soluble carbohydrates (WSC), proline, and soluble protein in leaf tissues. The transgenic plants had higher IAA and lower ABA content relative to WT plants. The results suggest that the improvement of drought tolerance in transgenic Kentucky bluegrass overexpressing the DREB1A gene may have resulted from increased accumulation of organic solutes (WSC, proline, and protein) and alteration in hormone metabolism.