Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2018
Publication Date: 3/20/2018
Citation: Schroeder, B.K., Schneider, W.L., Luster, D.G., Sechler, A.J. 2018. Rathayibacter agropyri (non O’Gara 1916) comb. nov., nom. rev., isolated from western wheatgrass (Pascopyrum smithii). International Journal of Systematic and Evolutionary Microbiology. 68:1519–1525. https://doi.org/10.1099/ijsem.0.002708.
Interpretive Summary: Rathayibacter toxicus is abacterium that is a serious threat to agriculture and food security because it generates a toxin in forage grasses that causes death in livestock. Previously scientists believed that the production of toxin was caused by the infection of the bacterium by a virus. However, some evidence suggested that the bacterium was capable of producing toxin without virus infection. To help determine the role of the virus in toxin production the DNA from the virus was sequenced. 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, with no particular relation to known genes from other living organisms. Most importantly, the genes responsible for toxin production were not found on the viral genome.
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 CS14phi. However, one paper indicated that R. toxicus was capable of producing tunicamycin without CS14phi. To help determine the role of the phage the complete genome of CS14phi 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.