XVI International Botanical Congess

A cDNA(PchExp1) homologous to expansin protein was isolated from ripening peach fruit. The deduced amino acid sequence of PchExp1 showed significant similarity to the sequences of expansins from other plants. Northern blot analysis showed that PchExp1 was abundantly expressed in ripe fruit, but absent in other tissues tested. To clarify the relation between PchExp1 and fruit softening, the mRNA accumulations during ripening after harvest were compared between melting cultivar and stony-hard cultivar. PchExp1 mRNA remained abundantly accumulated in ripe fruits, 0 to 8 days after harvest, in both cultivars. These results suggest that PchExp1 is related with fruit ripening, but increased accumulations of PchExp1 mRNA may not solely regulate peach fruit softening.