A DNA methylation survey of NCED gene in Vitis vinifera, under stress conditions.

The phytohormone abscisic acid (ABA) regulates many key processes in plants, such as seed germination, seedling growth, and abiotic stress tolerance. In particular, drought stress signals are transmitted through at least two pathways: one is abscissic acid (ABA)-dependent, and the other is ABA-independent. In the ABAdependent pathway, drought stress increases the cellular ABA levels, which induce the expression of drought stress-responsive genes, such as 9-cis-epoxycarotenoid dioxygenase (NCED). The stress memory can be stored in the short-term, depending on the half-life of stress-induced proteins, RNAs, and metabolites, or for the longterm, by reprogramming phenology and morphology. DNA methylation and histone modification are stable and heritable epigenetic processes involved in long-term stress memory. Recent discoveries reveal that, in addition to genetic regulation, epigenetic regulation plays a key role in ABA-mediated plant processes. Our interest is on studying the methylation status of NCED genes as candidate genes under normal and drought-stressed conditions in the framework of “epigenetic memory” in Vitis vinifera. We have identified symmetric and asymmetric CpG islands in the full sequences of genes which carry on DNA methylation by bisulfite analysis. These results will be considered along with the expression patterns of stress-induced genes.