Expressed sequence tags of ovary tissue cDNA library in Citrus unshiu Marc

To characterize the gene expression and regulation associated with anthesis stage of fruit development a total of 824 clones were randomly selected and sequenced from a cDNA library prepared from ovary tissue of Satsuma mandarin (Citrus unshiu Marc) at the anthesis stage. Clones derived from rDNA, mitochondrial and chloroplastic DNAs were removed and the remaining 544 cDNA clones were analyzed for homology with known sequences. From this analysis 455 clones were identified as homologues of a known gene or an expressed sequence tag (EST). We found 103 cDNA clones that were not detected in our previous analyses of Citrus ESTs including gene homologues related to transcription factors, molecular chaperones, and plant hormone biosynthesis/regulation. In addition, gene homologues related to amino acid biosynthesis, secondary metabolism and stress response were frequently detected, indicating that the ovary tissue may be metabolically active and have the intrinsic ability to react to biotic and abiotic stresses.