Having established that JAs induce relevant changes in ripening physiology, a transcriptome analysis was conducted in fruit at first harvest. Hybridization of lPEACH1.0 with cDNA probes from mesocarp of MJ treated and control fruit allowed the identification of 80 differentially expressed genes (see Supplementary data at JXB online), of which 33 were down-regulated and 47 upregulated. Out of all 80 genes, those (30) relevant to fruit development and ripening are listed in Table 2. In particular, as regards ethylene biosynthesis, a downregulation of PpACO1 was detected. Moreover, 12 of these genes are involved in transcriptional regulation. Among these, genes coding for a transcription factor with high similarity to the tobacco LIM1 (Kawaoka et al., 2000), a tousled-like protein kinase, and two leucine-rich repeat (LRR) proteins were up-regulated. In contrast, a gene showing similarity to Arabidopsis IAA7 was down-regulated; IAA7 is a repressor of IAA-induced gene expression, belonging to the AUX/IAA family of transcriptional modulators (Zenser et al., 2001).