ABSTRACT
This chapter discusses the role of abscisic acid (ABA) in cold acclimation and in regulation of genes induced during the acclimation response. It shows that application of ABA to the growth medium of in vitro grown Arabidopsis thaliana seedlings results in increased freezing tolerance to the same extent as achieved by low temperature (LT)-induced acclimation. The small weed A. thaliana belonging to the family Crucifer has many of the characteristics of an ideal model plant for genetic and molecular studies of many fundamental plant processes. The chapter shows that ABA plays a key role in A. thaliana cold acclimation as suggested by the following lines of evidence: exogenous ABA induces freezing tolerance; elevated levels of ABA can be detected in cold-acclimated plants. A majority of the LT-induced proteins are induced by exogenously applied ABA in accordance with the hypothesis that ABA would constitute the signal for cold acclimation.
