Transcriptomic study of apricot fruit (Prunus armeniaca) ripening among 13 006 expressed sequence tags

To improve the knowledge of fruit ripening and to provide genomic resources for molecular breeding of apricot (Prunus armeniaca L), 13 006 expressed sequence tags (ESTs) were generated from three lambda zap cDNA libraries of the pericarp tissues at different stages of development (Physiol Plant 105: 294-303), yielding 5219 (40%) Unigenes. At this stage, the very low interlibrary redundancy indicated that EST sampling of the transcriptome of apricot pericarp is still far from being saturated. Seventy-six percent of Unigenes displayed homologies with public sequences and were clustered into functional categories. The largest expressed categories were related to primary metabolism, stress response, and protein synthesis. Electronic Northern analysis revealed that stress-related proteins and cell wall modification-related enzymes strongly increased during ripening. Among 448 isoproteins (amino acid-level isogenes) detected in the Unigene set, 186 (42%) displayed significant homologies in their coding regions (nucleic acid-level isogenes).