Generation of transgenic tall fescue plants with enhanced abiotic stress tolerance

摘要

Environmental stresses, such as drought, salinity and temperature extremes significantly decrease the yield of forage crops. Therefore, traits associated with abiotic stress-tolerance are of prime importance for their improvement. Biotechnological approaches have the potential to accelerate and complement conventional breeding by extending the range of gene sources for valuable traits, thus offering new opportunities for forage improvement. Transgenic technology appears as an efficient biotechnological tool of molecular breeding for improving forage quality and yield as well as tolerance to various environmental stresses. Occurrence of high level of reactive oxygen species (ROS) is a common phenomenon in abiotic stress-challenged plants. Plants havebeen evolved with a number of protective mechanisms to counteract such oxidative stress. Molecular chaperones play crucial roles against oxidative stress. Heat shock proteins (HSPs) are molecular chaperones that provide thermotolerance in plants (Heckathorn et al. 1998). It has been reported that chloroplast-localized small HSPs protect thermolabile photosystem II (PSII) in isolated chlo-roplasts in vitro and are important for heat acclimation (Heckathorn et al. 1998). A number of previous reports havedemonstrated that ABA is essential for the adaptive response to drought stress (Xiong et al. 2002). ABA-responsive elements (ABRE)-binding bZIP proteins (ABFs) have been isolated (Choi et al. 2000) and mediate ABA-dependent stress signaling in Arabidopsis (Uno et al. 2000). Overexpression of ABF increased tolerance todrought or heat stress (Vanjildorj et al. 2006). In this project, we generated transgenic tall fescue plants over-expressing chloroplastic small HSP or ABF, and investigated their performance under abiotic stresses.