Construction Of Rd29A Promoter-ABP9-GFP Fusion Gene And Expression In Transgenic Arabidopsis Plant

Low temperature, drought, and high salinity are common stress conditions that adversely affect plant growth and crop productivity. It is well known that in China there are lots of droughty and semiarid land, accounting for 38% of the arable land, and great acres of saline soil need increasing productivity and reclamation. In addition, low/freezing temperatures restrict the planting and harvest of crops in a year-round manner. Therefore, enhancing the plant ability against environmental stresses is critical for increasing the yield of crops.Oxidative stress is the common mechanism by which abiotic stresses affect plant growth and development. Plant respond to conditions of severe environmental changes or stresses, such as drought, low temperature, or high salt, with a number of physiological and developmental changes. ABA is produced under such condition and plays important roles in tolerance against these stresses. But the endogenous level of plant hormone ABA (Absicisic Acid) rapidly increases will lead to excess production of reactive oxygen species (ROS), resulting in the formation of oxidative stress that causes irreversible injuries to plants. To scavenge excess ROS and reduce its toxic effects, plants have evolved an antioxidant system whose activity is up-regulated under stressful conditions and correlated well with enhanced tolerance. However, due to the poor capability for induction of the various enzymes of the antioxidant defense system, the degree of the enhancement is limited. Therefore, a more enhanced anti-oxidant ability is required for improving plant stress tolerance.As a part of the anti-oxidant system of Maize, Call gene plays an indispensable role inscavenging excess cellular H2O2. Our previous studies have demonstrated that the expression of Catl is ABA-inducible which is mediated by ABRE2 motif in its promoter and transcription factor ABP9 that specifically interacts with ABRE2 motif of Maize Catl gene has been cloned. ABP9 can trigger the expression of a battery of stress-related genes and contributes to the improvement of plant performance under abiotic stresses. We found that the constitutive promoter CaMV 35S can drive the expression of ABP9 in transgenic plant and enhance the plants stress tolerance in some degree. But the 35S:ABP9 plants exhibited varying degrees of growth retardation under control condition. The extent of both growth retardation under control conditions and stress tolerance correlated with the level of constitutive expression of the ABP9 and its target genes. The results indicate that stress tolerance of the 35s:ABP9 plant comes at the expense of growth.The stress-inducible promoter named rd29A promoter was adopted to drive the expression of the ABP9 in the plant to resolve the problem about growth retardation. To analysis the expression of ABP9 in transgenic plant, the plant expression vectors pZP212-rd29Apromoter-ABP9 and pZP212-rd29Apromoter-ABP9-GFP was constructedBy means of Agrobacterium tumefaciens -mediated, two constructs were transformed into plant then obtained transgenic plant. Growth of the transgenic transformants was compared with wild-type control plants. The Expression of ABP9 from the rd29A promoter gave rise to few effects on plant growth under normal growthing conditions. To research whether rd29A promoter can drive the expression of ABP9 in environmental stresses ,rd29A promoter:ABP9-GFP plant grow in pot where exposed to temperatures of 4 ℃ for 2 day. The expression of GFP can be detected by fluorescence microscope in the root of transgenic plant. But the GFP cannot be detected in the transformants, which did not suffer the cold .The above-mentioned result revealed that rd29A promoter can drive the expression of ABP9 in abiotic stresses.