Regulation of a Wheat Actin-Depolymerizing Factor during Cold Acclimation

• Published in: Plant physiology (Bethesda) Vol. 125; no. 1; pp. 360 - 368
• Main Authors: Ouellet, François, Éric Carpentier, M. Jamie T. V. Cope, Monroy, Antonio F., Sarhan, Fathey
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.01.2001
• Subjects: Acclimatization; Acclimatization - physiology; Actin Depolymerizing Factors; Actins; Amino Acid Sequence; Biological and medical sciences; Chromosomes; Cloning, Molecular; Cold Temperature; Destrin; Environmental Stress and Adaptation; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Low temperature; Microfilament Proteins - chemistry; Microfilament Proteins - genetics; Microfilament Proteins - metabolism; Microfilaments; Molecular Sequence Data; Phosphorylation; Physical agents; Phytopathology. Animal pests. Plant and forest protection; Plant physiology and development; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Protein Kinases - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Triticum - genetics; Triticum - physiology; Vegetative apparatus, growth and morphogenesis. Senescence; Weather damages; Weather damages. Fires; Yeasts; Monocotyledones; Phosphorylation; Enzyme; Cold resistance; Transferases; Cereal crop; Arrangement; Depolymerization; Regulation(control); Sensitivity resistance; Gramineae; Ultrastructure; Actin; Protein kinase; Angiospermae; Cytoskeleton; Spermatophyta; Intraspecific comparison; Biological accumulation; Triticum aestivum; Adaptation
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.125.1.360

We have previously shown that the wheat (Triticum aestivum) TaADF gene expression level is correlated with the plants capacity to tolerate freezing. Sequence analysis revealed that this gene encodes a protein homologous to members of the actin-depolymerizing factor (ADF)/cofilin family. We report here on the characterization of the recombinant TaADF protein. Assays for ADF activity showed that TaADF is capable of sequestering actin, preventing nucleotide exchange, and inducing actin depolymerization. In vitro phosphorylation studies showed that TaADF is a substrate for a wheat 52-kD kinase. The activity of this kinase is modulated by low temperature during the acclimation period. Western-blot analyses revealed that TaADF is expressed only in cold-acclimated Gramineae species and that the accumulation level is much higher in the freezing-tolerant wheat cultivars compared with the less tolerant ones. This accumulation was found to be regulated by a factor(s) encoded by a gene(s) located on chromosome 5A, the chromosome most often found to be associated with cold hardiness. The induction of an active ADF during cold acclimation and the correlation with an increased freezing tolerance suggest that the protein may be required for the cytoskeletal rearrangements that may occur upon low temperature exposure. These remodelings might be important for the enhancement of freezing tolerance.