Abscisic acid deficiency prevents development of freezing tolerance in Arabidopsis thaliana (L.) Heynh.

Abstract

Abscisic acid (ABA) has been implicated as a regulatory factor in plant cold acclimation. In the present work, the cold-acclimation properties of an ABA-deficient mutant (aba) of Arabidopsis thaliana (L.) Heynh. were analyzed. The mutant had apparently lost its capability to cold acclimate: the freezing tolerance of the mutant was not increased by low temperature treatment but stayed at the level of the nonacclimated wild type. The mutational defect could be complemented by the addition of exogenous ABA to the growth medium, restoring freezing tolerance close to the wild-type level. This suggests that ABA might have a central regulatory function in the development of freezing tolerance in plants. Cold acclimation has been previously correlated to the induction of a specific set of proteins that have been suggested to have a role in freezing tolerance. However, these proteins were also induced in the aba mutant by low temperature treatment.

Wild-Type Levels of Abscisic Acid Are Not Required for Heat Shock Protein Accumulation in Tomato

“…These results indicated that levels of ABA in WT were not required for changes in gene expression that occurred during heat shock of detached tomato leaves. This is analogous to results obtained with an ABAdeficient mutant ofArabidopsis in response to cold stress (12). The same cold-induced polypeptides are observed in both genotypes.…”

“…This difference in heat tolerance may be a direct effect of ABA or an indirect effect. In response to low temperature stress, the ABA-deficient mutant of Arabidopsis is also slightly less tolerant and is not able to develop cold hardiness ( 12).…”

“…Some of the functions of endogenous ABA have been demonstrated using mutants that are deficient in ABA. These mutants have impaired stomatal function (18), do not accumulate drought-induced gene products (3,6), and do not develop cold hardiness (12) as a direct result of reduced ABA levels. Exogenous ABA treatments have been used to demonstrate the possible range of responses to the environment that ABA may control.…”

The SENSITIVE TO FREEZING2 Gene, Required for Freezing Tolerance in Arabidopsis thaliana, Encodes a β-Glucosidase

“…The frs1 mutation was found to be an allele of ABA3 (Llorente et al, 2000), confirming the necessity for normal abscisic acid signaling during cold acclimation (Heino et al, 1990). The freezing sensitivity of two sensitive to freezing (sfr) mutants has been interpretable in terms of prior knowledge about freezing tolerance.…”

Drought Rhizogenesis in Arabidopsis thaliana (Differential Responses of Hormonal Mutants)

“…This result is in agreement with the numerous lines of evidence supporting the critica1 role that ABA plays in plant adaptation to various forms of environmental water stress. For instance, the Arabidopsis aba mutant is impaired in cold acclimation (Heino et al, 1990;Gilmour and Thomashow, 1991). Mutations at the abil versus abi2 or abi3 loci clearly have a distinct effect on the intensity of drought rhizogenesis.…”