Vegetative-bud dormancy in peach (Prunus persica L. Batsch) trees is known to be correlated, at least partially, with properties of the underlying bud tissues during winter. Variations in the activity and amount of plasma-membrane H -ATPase were observed. A full-length cDNA, PPA2 (Prunus persica H+-ATPase 2) and three partial cDNAs (PPA1, PPA3 and PPA4) for the plasma-membrane H+-ATPase from peach trees were isolated by reverse transcription (RT)-coupled rapid amplification of cDNA ends (RACE) polymerase chain reaction (PCR). The accumulation of plasma membrane H+-ATPase transcripts was then studied in vegetative buds during dormancy and breaking of dormancy. Competitive RT-PCR analysis revealed that, during dormancy, the plasma membrane H+-ATPase transcripts were higher in the tissues underlying the buds than in the buds themselves. After dormancy release, the level of PPA1, 2, 3 mRNA increased, whereas the level of PPA4 decreased in the buds. When trees were kept in a greenhouse (i.e. sheltered from chilling), no accumulation of PPA mRNA could be detected. These results suggest that there is a differential accumulation of H+-ATPase mRNA between the bud and the underlying bud tissues during dormancy, and that chilling could act as a decisive factor.