Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 14, 2002
Publication Date: January 12, 2003
Citation: Bausher, M., Shatters, R., Chaparro, J., Dang, P.M., Hunter, W., Niedz, R. 2003. An expressed sequence tag (EST) set from Citrus sinensis L. Osbeck whole seedlings and the implications of further perennial source investigations. Plant Science. 165(2):415-422.
Unlike annual plants, the number of large-scale single pass cDNA sequencing entries in the NCBI database projects for perennial plants is scarce. Perennial plant species have some unique characteristics not found in annual species. For example, perennials must survive for long periods of time in a single location and resist or avoid environmental, disease, and predation stresses. This suggests unique, compared to annuals, gene expression and metabolic pathways. Phloem tissue was selected as it is a specialized tissue important in disease resistance, carbohydrate and peptide transport, and general growth and development. We constructed and sequenced 2970 random cDNA clones of a phloem library from mature grafted 7 year old trees of sweet orange (Citrus sinensis L. Osbeck). The data consists of 1851 unique singlets and 317 unique contigs represented by two or more sequences. Assemblies with BLAST analysis indicated that approximately 37% of the sequences have no significant homology to current dbEST entries. The high level of novel sequences in this data set is evidence that perennial trees are an important source of genetic diversity not duplicated in typical annual model plant species.