Janus-faced nature of light in the cold acclimation processes of maize

Earlier findings indicated that light plays a critical role in the development of frost tolerance in winter cereals. However, the exact mechanism is still poorly understood. In the present work the effects of light during the cold acclimation period were studied in chilling-sensitive maize plants. The results show that although exposure to relatively high light intensities during cold acclimation at 15 °C causes various stress symptoms, it enhances the effectiveness of acclimation to chilling conditions (5 °C in the light). Interestingly, certain stress responses were light-dependent not only in the leaves, but also in the roots. A microarray study was also conducted to achieve a better understanding of the interaction of low temperature and light intensity during the cold hardening period. Numerous genes significantly differentially expressed were observed in almost all assimilation and metabolic pathways. Acclimation at moderately low temperature and low light intensity reduced the level of soluble sugars, while chilling increased it. Greater accumulation during hardening was detected at relatively high light intensity. It seems that the photoinhibition induced by low temperature is a necessary evil for cold acclimation processes in plants. Control and cold-induced maize plants were sampling at different growth light intensities