Temperate herbaceous plants sense environmental changes during fall and increase their freezing tolerance, which is critical for survival over winter. This process, called as cold acclimation (CA), has been known to be mainly regulated by changes in temperature in season. However, changes in air temperature has been unpredictable and often show sudden risings and/or drops, which is worsened with global climate changes. Light conditions, in addition to lowering temperature, are known as another important factor to regulate CA and, in fact, shortening the day length as well as changes in red/far red light conditions affects the extent of CA. However, effects of light quality and the combination of temperature and light remain to be studied in detail. With Arabidopsis, we here report that light conditions (blue light as well as red light) and temperature conditions in day and night periods (constant vs fluctuated) influence freezing tolerance in complex way. We will discuss elaborate systems for plants to prepare for winter beforehand even under unpredictable climate conditions in the global climate change era.
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