Submitted to: Genome Announcements
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2017
Publication Date: 10/19/2017
Citation: Schneider, W.L., Sechler, A.J., Rogers, E.E. 2017. Complete genome sequence of the Rathayibacter toxicus phage NCPPB3778. Genome Announcements. 5(42):e00671-17. https://doi.org/10.1128/genomeA.00671-17.
Interpretive Summary: Rathayibacter toxicus is a bacteria that causes a serious threat to agriculture and food security. The bacterium, which infects annual ryegrass, produces a toxin that can kill livestock when infected ryegrass is eaten. Previously scientists believed that the production of the toxin was caused by the infection of bacteria by a virus. To figure out how toxin is produced we sequenced the DNA of the virus. The virus had 77 genes, which code for the functional proteins that viruses use to infect their hosts. Some of the genes were very typical viral genes, some of the genes were related to bacterial genes, but most of the genes were very novel. Most importantly, the genes responsible for toxin production were not found on the viral DNA. This suggests that toxin production comes from the bacteria, and future research to stop toxin production needs to focus on the bacteria.
Technical Abstract: Rathayibacter toxicus is a select agent plant pathogen largely due to the fact that it generates a toxin (tunicamycin) in forage grasses that causes death in livestock, a disease called annual ryegrass toxicity (ARGT). The majority of previous literature suggested that toxin production and ARGT was due to the interaction of R. toxicus and a phage called CS14'. However, one paper indicated that R. toxicus was capable of producing tunicamycin without CS14'. To help determine the role of the phage the complete genome of CS14' was sequenced. The genome was 44,520 nt in length with 77 predicted genes. About half of the genes were completely novel, with no relation to any other organisms. One third of the genes showed high similarity to a family of phages called siphoviruses. The remaining portions of the genome had various levels of similarity to bacterial genes. The genes responsible for toxin production were not found on the viral genome.