High throughput sequencing of a stem pitting citrus tristeza virus isolate from Hunan Province P.R. China

A stem-pitting isolate of citrus tristeza virus (CTV), spreading in Hunan province of  China (HU-PSTS), was sequenced and indexed on indicator plants. Biological assays showed that HU-PSTS is a highly aggressive stem pitting isolate belonging to biogroup 5. Viral small RNAs (18-26 nt) of the isolate were deep sequenced by Illumina technology to gain genomic information on the CTV strain infecting the source plant. The reads mapping with 17 CTV reference genomes enabled us to re-assemble the genomes of VT, T68, T30 and T3 strains. Among the VT, the highest number of mapped reads (47-41%) was with SG29, T318A, CT11A, Nuaga and AT-1 genomes, whereas T68, T30 and T3 genomes were less represented (28-20%). Alignments with genomes belonging to T36 and RB strains revealed percentage of mapped reads ranging from 10 to 12%. This is the first sequenced genome of a CTV isolate from Hunan province. According to the results, further sequencing and bioindexing need to be developed to explore the potential of a local cross protective strategy.