High expression level of a gene coding for a chloroplastic amino acid selective channel protein is correlated to cold acclimation in cereals.
A cold-regulated gene (cor tmc-ap3) coding for a putative chloroplastic amino acid selective channel protein was isolated from cold-treated barley leaves combining the differential display and the 5'-RACE techniques. Cor tmc-ap3 is expressed at low level under normal growing temperature, and its expression is strongly enhanced after cold treatment. A positive correlation between the expression of cor tmc-ap3 and frost tolerance was found both among barley cultivars and among cereal species. The COR TMC-AP3 protein was expressed in vitro, purified and used to raise a polyclonal antibody. Western analysis showed that the cor tmc-ap3 gene product is localized to the chloroplastic outer envelope fraction, supporting its putative function. The frost-resistant winter cultivar Onice accumulated COR TMC-AP3 more rapidly and at a higher level than the frost-susceptible spring cultivar Gitane. After 28 days of cold acclimation the winter cultivar had about 2-fold more protein than the spring genotype. All these results suggest that an increased amount of a chloroplastic amino acid selective channel protein could be required for cold acclimation in cereals. Hypotheses about the role of COR TMC-AP3 during the hardening process are discussed.
Baldi
P
P
Istituto Sperimentale per la Cerealicoltura, Fiorenzuola d'Arda (PC), Italy.
Grossi
M
M
Pecchioni
N
N
Valè
G
G
Cattivelli
L
L
D000064:Acclimatization; D000595:Amino Acid Sequence; D000596:Amino Acids; D001483:Base Sequence; D015153:Blotting, Western; D002736:Chloroplasts / Q000235:genetics; D003080:Cold Temperature; D018744:DNA, Plant; D002523:Edible Grain; D015870:Gene Expression; D017343:Genes, Plant; D018745:Genome, Plant; D001467:Hordeum / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D000596:Amino Acids; D018744:DNA, Plant; D010940:Plant Proteins; C402102:cor tmc-ap3 protein, Hordeum vulgare