CLONING AND CHARACTERIZATION OF cDNA CLONE ENCODING EXPANSIN FROM PEACH FRUIT

National Institute of Fruit Tree Science (NIFTS), Tsukuba, Ibaraki 305-8605, Japan

Expansins are extracellular proteins that increase plant cell wall extensibility in vitro and have been proposed to disrupt noncovalent interaction between hemicellulose and cellulose microfibrils. The cDNAs encoding expansins had been isolated from various plant tissues such as cucumber hycopotyls, rice internodes, cotton fibers and ripening fruits of tomato, melon and apricot. The studies of expansins have focused on their roles in cell growth and cell wall relaxation, but the roles in fruit tissue are still unknown. We isolated a partial length of cDNA clone encoding expansin (PchExp1) from peach fruit (Prunus persica cv. Akatsuki) by reverse transcription PCR (RT-PCR) method. A search of the GenBank database with the deduced amino acid sequence of PchExp1 indicated the high sequence similarities with plant expansin genes, especially highest with apricot expansin (AP-Exp2). Southern blot analysis showed the expansin genes formed a multigene family. We also analyzed the expression patterns of PchExp1 during peach fruit development and at various peach tissues to clarify its roles in fruit tissue.