Journal Article

Arabidopsis thaliana avoids freezing by supercooling

Reyes-Díaz, Marjorie, Ulloa, Nancy, Zúñiga-Feest, Alejandra, Gidekel, Manuel, Corcuera, Luis J., Alberdi, Miren, Bravo, León A., Gutiérrez, Ana

2006

Overview

Arabidopsis thaliana (L.) Heynh. has been described as a freezing-tolerant species based on freezing-resistance assays. Nonetheless, this type of experiment does not discriminate between freezing-tolerance and freezing-avoidance mechanisms. The purpose of this paper was to determine which of these two freezing-resistance mechanisms is responsible for freezing resistance in A. thaliana. This was achieved by comparing the thermal properties (ice-nucleation temperature and the freezing temperature) of leaves and the lethal temperature to 10, 50 and 90% of the plants (LT₁₀, LT₅₀, and LT₉₀, respectively). Two wild-type genotypes were used (Columbia and Ler) and their mutants (esk-1 and frs-1, respectively), which differ in their freezing resistance. This study's results indicated that the mutant esk-1, described as a freezing-tolerant species showed freezing tolerance only after a cold-acclimation period. The mutant frs-1, described as freezing sensitive, presented freezing avoidance. Both wild genotypes presented LT₅₀ similar to or higher than the ice-nucleation temperature. Thus, the main freezing-resistance mechanism for A. thaliana is avoidance of freezing by supercooling. No injury of the photosynthetic apparatus was shown by measuring the maximal photochemical efficiency (Fv/Fm) and pigments (chlorophyll and carotenoid) during cold acclimation in all genotypes. During cold acclimation, Columbia and esk-1 increased total soluble carbohydrates in leaves. esk-1 was the only genotype that presented freezing tolerance after cold acclimation. This feature could be related to an increase in sugar accumulation in the apoplast.

• Publisher: Oxford University Press,Oxford Publishing Limited (England)
• Subject: acclimation / Acclimatization / analysis / Apoplastic fluid / Arabidopsis / Arabidopsis - genetics / Arabidopsis - metabolism / Arabidopsis - physiology / Arabidopsis thaliana / Biological and medical sciences / carbohydrate content / Carbohydrate Metabolism / Carbohydrates / carotenoids / chlorophyll / chlorophyll fluorescence / Chlorophylls / cold acclimation / cold stress / Cold Temperature / cold tolerance / esk-1 / Fluorescence / Freezing / freezing avoidance / freezing point / freezing tolerance / frost / frost injury / frost resistance / frs-1 / Fundamental and applied biological sciences. Psychology / Genes. Genome / genetics / Genotype / Genotypes / Ice / ice nucleation / intercellular spaces / Leaves / metabolism / Molecular and cellular biology / Molecular genetics / mortality / mutants / Mutation / Nucleation / Photochemicals / photosynthesis / Photosynthesis - physiology / physiology / Pigments, Biological / Pigments, Biological - analysis / Plant Leaves / Plant Leaves - genetics / Plant Leaves - metabolism / Plant Leaves - physiology / Plant physiology / Plants / Research Papers / sucrose / Sugars / Supercooling / Thermal properties / total soluble sugars