Title : A Novel CBF from Oil Palm that Regulates Abiotic Stress Response and the Ripening Process through Modulation of the Ethylene Signaling Pathway
Abstract:
A novel C-repeat binding factor (CBF) encoding an AP2-domain protein isolated from oil palm fruit (EgCBF3) demonstrated the highest expression level in the mesocarp at the ripening stage. In the mesocarp tissue, expression of EgCBF3 was upregulated by abiotic stresses including cold, drought and salt stresses as well as phytohormones (ethylene and ABA) treatments. EgCBF3 was shown to bind to DRE/CRT promoter element through in vitro electrophoretic mobility shift assay (EMSA) and in vivo yeast-one hybrid assay. Transient expression of EgCBF3 in tomato fruits influenced the expression profile of the ethylene and abscisic acid biosynthesis-related and ripening-related genes indicating that EgCBF3 can mediate abiotic stress response in ripening fruits and may function as a regulator of ripening process-related genes. The effects of ectopic expression of EgCBF3 in transgenic tomato were also studied. The EgCBF3 tomatoes demonstrated altered phenotypes compared to the wild type tomatoes. These include delayed leaf senescence and flowering, increased chlorophyll content and abnormal flowering. The EgCBF3 tomatoes demonstrated enhanced abiotic stress tolerance under in vitro conditions. In addition, the expression levels of ethylene biosynthesis-related genes were altered in the EgCBF3 tomato leaves and roots compared to that in the wild type tomato plant. Altered expression of eight antifreeze protein genes was also observed. Together, the results of this study suggest possible role of EgCBF3 in regulating abiotic stress response and the ripening process through modulation of the ethylene signaling pathway
