The libraries that made SUCEST

Abstract

A large-scale sequencing of sugarcane expressed sequence tags (ESTs) was carried out as a first step in depicting the genome of this important tropical crop. Twenty-six unidirectional cDNA libraries were constructed from a variety of tissues sampled from thirteen different sugarcane cultivars. A total of 291,689 cDNA clones were sequenced in their 5′ and 3′ end regions. After trimming low-quality sequences and removing vector and ribosomal RNA sequences, 237,954 ESTs potentially derived from protein-encoding messenger RNA (mRNA) remained. The average insert size in all libraries was estimated to be 1,250bp with the insert length varying from 500 to 5,000 bp. Clustering the 237,954 sugarcane ESTs resulted in 43,141 clusters, from which 38% had no matches with existing sequences in the public databases. Around 53% of the clusters were formed by ESTs expressed in at least two libraries while 47% of the clusters are formed by ESTs expressed in only one library. A global analysis of the ESTs indicated that around 33% contain cDNA clones with full-length insert.