AbstractsBiology & Animal Science

Cold resistance of plants is an important characteristic that restricts plant distribution, growth and biomass productivity. Cold acclimation is a phenomenon that occurs in some plants as an increase in cold tolerance upon exposure to low, non-freezing temperatures. The CBF/DREB1 gene family is a small group of transcription factors that play key roles in cold acclimation. The CBF/DREB1 genes were first identified from the model plant Arabidopsis , then from many economically important plant species including grape, tomato, corn, rice, and barley. Overexpression of CBF/DREB1 genes induces multiple components of cold acclimation and thus increases plant cold tolerance even without cold stimulus. To systematically study the cold resistance mechanism of palms, CBF/DREB1 orthologs were isolated from various palms, including both cold-resistant and cold-sensitive species. This is the first report of CBF/DREB1 genes in the Palmae family. Analyses of DNA and putative protein sequences confirmed that the palm CBF/DREB1 has similar structures with known CBF proteins. To further investigate the functions of the palm CBF/DREB1 genes, the expression patterns of two Rhapidophyllum hystrix CBF orthologs, RhCBF1 and RhCBF2 , were analyzed with reverse transcription and real-time PCR. The expressions of the two RhCBFs were constitutive yet cold-inducible, which provided further evidence of the involvement of these genes in cold acclimation response of palms. The two RhCBF genes were transformed into Arabidopsis. The transgenic Arabidopsis plants showed increased cold tolerance, typical growth retardation of CBF -overexpessing plants, and other multiple CBF -related cellular changes. The results indicated that RhCBFs had functional similarity with Arabidopsis CBF genes also.