An expressed sequence tag (EST) set from Citrus sinensis L. Osbeck whole seedlings and the implications of further perennial source investigations

• Author(s): Bausher, M.; Chaparro, J.; Dang, P.; Hunter, Wayne; Niedz, R.; Shatters, R.;
• Abstract: There are a number of large-scale single past cDNA sequencing entries from annual plants in the NCBI database. However, NCBI has very little information on perennial species. As of November 2002 of the 1,100,000 entries less than 5 percent of the publicly available sequence information represent these plants. Because perennials are unique in their ability to survive pathological and environmental onslaughts without the ability of short cycle reproduction as an escape mechanism, these plants represent a reservoirs of EST information most likely not found in annual species. Tree genomes, especially Citrus, contain genes that encode proteins involved in important traits including- essential oil production, fruit production, dormancy, apomixis, and evergreen and deciduous types. ESTs are an excellent tool to identify and catalog many of the genes responsible for these important metabolic pathways in perennial trees species like Citrus. We describe here a set of ESTs produced from mRNA isolated from 180-day-old whole immature sweet orange Citrus seedlings. From this library, 6758 were sequenced and using several bioinformatics programs producing 922 unique contig composite assemblies with 2561 unique singlets. Based on BLAST comparisons, the data contains genes involved in a number of biochemical pathways, but approximately 30 percent have no significant homology to current dbEST entries. The high level of novel sequences in this database set is evidence that perennial trees are an important source of genetic diversity not duplicated in typical annual model plant species.
• Publication Date: Jan 2003
• Journal: Plant Science