CHARACTERIZATION OF A LOW-TEMPERATURE-INDUCED CDNA FROM WINTER BRASSICA-NAPUS ENCODING THE 70 KDA SUBUNIT OF TONOPLAST ATPASE

A cDNA clone, pBN59, was isolated by differential screening of a cDNA library of winter Brassica napus during cold acclimation. Nucleotide s equence of BN59 was found to be homologous to that encoding the 70 kDa subunit of the vacuolar H+-ATPase in plants. Transcripts hybridizing to BN59 accumulated during exposure to low temperatures and to the exo genous application of abscisic acid (ABA). Western blot analyses also indicated an increase in the 70 kDa subunit during cold acclimation. T he accumulation of an endomembrane H+-ATPase is consistent with the ob servation of osmotic adjustment, increases in endogenous ABA and the p roliferation of endomembranes during cold acclimation.