De novo assembly and characterization of Oryza officinalis leaf transcriptome by using RNA-seq.

Although endeavors have been made to identify useful wild rice genes that can be used to improve cultivated rice, the virtual reservoir of genetic variation hidden within the wild relatives of cultivated rice is largely untapped. Here, using next-generation sequencing technology, we investigated the leaf transcriptome of a wild rice O. officinalis with CC genome. Approximately 23 million reads were produced in the species leaf transcriptome analysis and de novo assembly methods constructed 68,132 unigenes. Functional annotations for the unigenes were conducted using sequence similarity comparisons against the following databases: the nonredundant nucleotide database, the nonredundant protein database, the SWISS-PROT database, the Clusters of Orthologous Groups of proteins database, the Kyoto Encyclopedia of Genes and Genomes database, the Gene Ontology Consortium database, and the InterPro domains database. In addition, a total of 476 unigenes related to disease resistance were identified in O. officinalis, and these unigenes can serve as important genetic resources for cultivated rice breeding and quality improvement. The present study broadens our understanding of the genetic background of non-AA genomic wild rice species and it also provides a bridge to extend studies to other Oryza species with CC genomes.