The Sugarcane EST project: towards defining the transcriptome of a complex eukaryote

The genome of sugarcane is one of the most complex among living organisms. It is characterized by a high level of polyploidy with current cultivated varieties being derived from interspecific hybridization between S. officinarum, a domesticated species and S. spontaneum, a wild relative. Various ploidy level – from 5x to 14x – have been reported for S. spontaneum. Cultivated varieties are often aneuploids, with chromosome numbers ranging between 100 and 130, 10% to 25% being contributed by S. spontaneum. It is estimated that a gene with a single locus in the sugarcane genome will be present in approximately 10 copies. Among those 10 copies, roughly eight or nine may be inherited from S. officinarum and one or two from S. spontaneum. We constructed 35 cDNA libraries from tissues representing all major organs, different developmental stages and many individual cell types. Clones from these libraries were random sequenced and processed by a set of computer programs and the data were organized in a detailed database called SUCEST (Sugarcane EST), which has already more than 250.000 high quality ESTs. A detailed analysis of gene expression profile and comparative-genomics with other plant and/or organisms will be presented.