COLD ACCLIMATION AND VEGETATIVE/REPRODUCTIVE TRANSITION IN WINTER CEREALS

Cereals display a broad capacity range to survive low temperatures (LT) and frost condition. Exposure of winter cereals to low, nonfreezing temperatures during the autumn and before freezing injury occurs can induces various changes in genome, transcriptome, proteome, and metabolom levels in plant cells, by which plants are able to adjust their metabolism to LT and improve their freezing tolerance (FT). The difference between the cultivars can be interpreted by hardening conditions and the different mode and severity of changes occurred in each levels during cold acclimation. FT in cereals is dependent upon phonological development and the highest level of FT only acquires during the vegetative stage and plants by initiation of the reproductive phase lose the ability for hardening. Phonological growth is controlled by the developmental genes (vernalization, photoperiod, etc.) which regulate the vegetative/reproductive transition and consequently determine the duration and level of FT expression. Furthermore under filed condition winter survival is also determined by the acclimation temperature of locations that may affect phenological development and delay the beginning of reproductive growth.