Physiological And Biochemical Responses In AtDREB1A- Transgenic Kentucky Bluegrass To Drought And Post-drought Recovery

Kentucky bluegrass (Poαpratensis L.) is a relatively common species of cool-season turfgrass widely used in gardens, parks, schools and playground because of its good landscape, ecology and sports functions. However, one main drawback of Kentucky bluegrass is its relatively high demand for water, which to a large extent affects its application. Researchers have used a variety of methods to improve turfgrass drought resistance, including by genetic engineering, which has been implemented on different plant species. Currently, an introduction of functional genes into callus or protoplast of specific turfgrass species via genetic engineering to improve plant stress tolerance has become a hotspot for the area.On the basis of previous studies, five AtDREB1A-transgenic lines of Kentucky bluegrass were selected in this study. Physiological and biochemical responses in AtDREB1A-tansgenic Kentucky bluegrass to water deficit and water recovery were discussed in detail, which included cell membrane permeability changes, osmotic adjustment, antioxidative metabolism, endogenous hormone metabolism, total nonstructural carbohydrates changes and other aspects. The relationship between these physiological and biochemical responses and drought resistance was further observed, which was undoubtedly of importance to understand AtDREB1A mechanisms and turfgrass drought improving and helped to further understand the molecular biological mechanisms of turfgrass drought resistance, providing a theoretical basis and technical guidance for us to cultivate new varieties through artificial means.The results showed that, accompanied with the same degree of water deficit and water recovery, AtDREB1A-transgenic Kentucky bluegrass had better lawn performance and were considered to be relatively membrane stable and permeability small, which meaned better drought withstanding and recovery ability. Plant cell structure stability was positively correlated with turf quality, leaf relative water content and chlorophyll content, respectively.Under severe water deficit, AtDREB1A-transgenic plants had lower osmotic potential and greater osmotic adjustment, which were better able to maintain moisture status and thus could survive longer. With increased levels of water deficit, leaf organic solutes (WSC, Proline, Soluble protein) were significantly correlated with an increased osmotic adjustment. AtDREB1A-transgenic plants could accumulate more soluble sugar, proline and soluble protein, showing its stronger ability to drought adaptation. After re-watering, transgenic plants also showed a strong ability to restore growth.Under water deficit, AtDREB1A-transgenic plants had higher antioxidant enzyme (SOD, POD, CAT, APX) activities and lower H2O2 concentration, indicating a stronger scavenging ROS (including H2O2) ability, thus protecting plants from oxidative damage; Transgenic plants had a higher content of IAA and a lower content of ABA. In the same externally applied water stress situation, transgenic plants experienced a relatively minor internal water deficit, indicating stronger drought avoidance.Under water deficit, transgenic plants and control plants accumulated TNC in varying degrees, transgenic plants had accumulated significantly higher TNC content, indicating stronger drought tolerance. After re-watering, transgenic plants were better able to use more energy (TNC) to sustain normal life activities, showing stronger recovery ability.Generally speaking, with same water deficit and water recovery, transgenic plants increased drought tolerance and showed more vitality through a variety of physiological and biochemical responses (cell membrane permeability changes, osmotic adjustment, antioxidative metabolism, endogenous hormone metabolism, TNC changes, etc.); After rewatering, transgenic plants represented stronger recovery ability. There exist more physiological and biochemical responses in AtDREB1A-trangenic plants to water deficit and water recovery, which collaborated and worked together to protect the structure and properties of macromolecules, increase osmotic adjustment, remove the generation of hazardous substances, change the balance of endogenous hormones and improve energy material synthesis, and thus jointly safeguarded the stability of the intracellular environment and maintained plant life and vitality.It could also be inferred from our results that DREB1A, as a single transcription factor, was sufficient to perform its function and start stress-induced gene expression, and then activate the appropriate protective metabolic pathways. As for the specific mechanisms at the molecular level, further study depends.