Functional analysis of type III secretion system and transcription activator-like effectors of Xanthomonas translucens, the causal agent of bacterial leaf streak on cereals
(2015)
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- Xanthomonas translucens is the causal agent of bacterial leaf streak, the most common bacterial disease of small grain cereals. To cause disease, most xanthomonads depend on a conserved type III secretion system (Hrp system), which translocates type III effectors (T3E) into plant host cells. Comparative genomics of several X. translucens strains revealed that they contain a hrp gene cluster the genomic organization which is different to that found in other Xanthomonas species. Inoculation methods of barley plants were optimized in order to permit quantitative pathogenicity assays. Mutations were generated in two conserved genes of the X. translucens hrp cluster, affecting hrcT and hgiA (HrpG-induced gene). Both mutations caused drastic reductions in symptom development on the host plant barley and a loss of hypersensitive response in the non-host plant pepper. Evidence is provided that the HgiA protein is an analog of the putative translocon protein HrpF. A specific family of T3Es, called Transcription Activator-Like Effectors (TALEs), modulates plant gene expression. Artificial TALEs were established as a test system for the contribution of plant target genes to disease. TALEs from X. translucens were found to have distinct characteristics compared to other Xanthomonas TALEs. This study identified a conserved TALE in barley-pathogenic xanthomonads, which strongly contributes to disease development.
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Pesce, C. (2015). Functional analysis of type III secretion system and transcription activator-like effectors of Xanthomonas translucens, the causal agent of bacterial leaf streak on cereals. https://hdl.handle.net/2078.5/187577