Monitoring gene expression along pear fruit development, ripening and senescence using cDNA microarrays

In order to elucidate the molecular events associated with pear (Pyrus communis L. cv. Rocha) fruit development and climacteric ripening, high-density cDNA microarrays were constructed. cDNA clones (1364 total) were isolated from a fruit cDNA library and from a subtractive library and arrayed. The expression of these ESTs was monitored from early fruit development, through ripening, until complete fruit senescence, allowing a global coverage of the entire fruit life. A comparison was made with fruit that failed to ripe (FR) due to precocious harvesting. Based on the similarities in transcript expression profiles ESTs were grouped in different clusters. Transcripts encoding kinases and phosphatases were induced specifically during early developmental stages of pear fruit. Another set of genes was activated at the onset of the climacteric period when fruit softening rates also increased. Among these were transcripts encoding for cell wall modifications and pigment and aroma biosynthesis. Transcripts putatively involved in defence response, oxidative stress, primary and secondary metabolism, signalling and transcription regulation were also isolated. According to our results main changes in expression profiles occur in two phases: the cessation of growth and entrance in the initial maturation stages (pre-climacteric), and the entrance into the climacteric period. (C) 2004 Elsevier Ireland Ltd. All rights reserved.