Abstract: The exopolysaccharide of Grifola frondosa possesses anti-tumor, anti-HIV, and anti-oxidant effects. In order to investigate the genetic basis for polysaccharide synthesis by G. frondosa, the transcriptome of G. frondosa was sequenced by high-throughput sequencing technology. A total of 74 575 910 reads and 10.4 G data were generated, which formed 18 077 Unigenes after de novo splicing. A total of 11 651 Unigenes were annotated in the Nr database. Among them, G. frondosa transcriptome had the most similar sequence (18.74%) to M. tumefaciens. A total of 8 332 Unigenes were annotated in the GO database, which were divided into 3 major categories: molecular composition, molecular function and biological processes, including 59 branches. Compared with the KEGG database, 5 200 Unigenes were annotated which belonged to 376 metabolic pathways. A total of 1 155 simple sequence repeat (SSR) loci were found in 18 077 Unigenes, among which the highest repeat was single nucleotide whereas the repetition of hexanucleotide was the least, and the frequency of A/T was the highest. In this study, 115 unigenes which have been annotated in the database of KEGG were related to the biosynthesis of polysaccharide by G. frondosa. These annotated Unigenes and the information about them can lay the foundation for further studies on polysaccharide metabolism pathways and related functional genes in G. frondosa.

Key words: Grifola frondosa, mycelium, transcriptome sequencing, functional annotation