Isolation of cDNA clones corresponding to genes differentially expressed in pericarp of mume (Prunus mume) in response to ripening, ethylene and wounding signals

Ripening of climacteric fruit is a complex developmental process that includes many changes in gene expression. Some ripening-regulated genes are responsive to ethylene and/or wounding signals. Wounding increased PmACS1 expression in Prunus mume ( Japanese apricot), but was negatively regulated by ethylene. However, exposure of freshly harvested mature green mume fruit to ethylene induced PmACS1. Fifteen complementary DNA clones corresponding to messenger RNAs differentially expressed in the pericarp of P. mume fruit in response to ripening, ethylene and wounding signals were isolated by differential display. Quantitative real-time PCR analysis distinctly showed that these genes are differentially regulated. Genes that were upregulated during fruit ripening include Pm15 (cinnamyl-alcohol dehydrogenase), Pm21 (2-oxoacid-dependent dioxygenase), Pm22 (1-acyl-sn-glycerol-3- phosphate acyltransferase), Pm27 (unknown function), Pm38 (alcohol dehydrogenase), Pm41 (no homology), Pm52 (no homology), Pm65 (pectate lyase), Pm68 (expansin), Pm69 (serine carboxypeptidase) and Pm94 (alcohol acyltransferase). Expression of most of these genes was also inducible by ethylene and some of them were inducible by wounding. Pm3 (water channel protein, MIP) and Pm8 (unknown function) were downregulated during ripening. Expression of Pm71 (no homology) and Pm74 (NAC family protein) did not increase during ripening or in response to ethylene, but was upregulated in response towounding. The possible physiological roles of these genes during ripening and in response to ethylene and wounding are discussed.