Interactions Between <i>Xanthomonas campestris</i> pv. <i>graminis</i> Strains and Meadow Fescue and Italian Rye Grass Cultivars

Michel, Vincent

doi:10.1094/pdis.2001.85.5.538

Cited by 16 publications

(14 citation statements)

References 12 publications

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“…Although other T3Es and resistance mechanisms that can trigger ETI are known in plant– Xanthomonas interactions, the absence of TALEs could be an indication for the absence of an HR, even on forage grasses with considerable resistance to Xtg . So far, HR symptoms have never been described in studies on bacterial wilt in forage grasses (Egli and Schmidt, ; Leyns, ; Michel, ). In a needle inoculation experiment using resistant L. multiflorum genotypes and the wild‐type Xtg 29 isolate, we failed to observe HR symptoms (data not shown).…”

Section: Resultsmentioning

confidence: 99%

The noncanonical type III secretion system of Xanthomonas translucens pv. graminis is essential for forage grass infection

Wichmann

Vorhölter

Hersemann

et al. 2013

Molecular Plant Pathology

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Xanthomonas translucens pv. graminis (Xtg) is a gammaproteobacterium that causes bacterial wilt on a wide range of forage grasses. To gain insight into the host-pathogen interaction and to identify the virulence factors of Xtg, we compared a draft genome sequence of one isolate (Xtg29) with other Xanthomonas spp. with sequenced genomes. The type III secretion system (T3SS) encoding a protein transport system for type III effector (T3E) proteins represents one of the most important virulence factors of Xanthomonas spp. In contrast with other Xanthomonas spp. assigned to clade 1 on the basis of phylogenetic analyses, we identified an hrp (hypersensitive response and pathogenicity) gene cluster encoding T3SS components and a representative set of 35 genes encoding putative T3Es in the genome of Xtg29. The T3SS was shown to be divergent from the hrp gene clusters of other sequenced Xanthomonas spp. Xtg mutants deficient in T3SS regulating and structural genes were constructed to clarify the role of the T3SS in forage grass colonization. Italian ryegrass infection with these mutants led to significantly reduced symptoms (P < 0.05) relative to plants infected with the wild-type strain. This showed that the T3SS is required for symptom evocation. In planta multiplication of the T3SS mutants was not impaired significantly relative to the wild-type, indicating that the T3SS is not required for survival until 14 days post-infection. This study represents the first major step to understanding the bacterial colonization strategies deployed by Xtg and may assist in the identification of resistance (R) genes in forage grasses.

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Section: Resultsmentioning

confidence: 99%

The noncanonical type III secretion system of Xanthomonas translucens pv. graminis is essential for forage grass infection

Wichmann

Vorhölter

Hersemann

et al. 2013

Molecular Plant Pathology

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“…Bragard et al (1997) considered the pathovar undulosa less aggressive than cerealis on oats. Similarly, the low incidence of symptoms produced by the three strains on ryegrass is associated with some strains of the pathovar graminis (Michel, 2001). However, the response of Lolium spp.…”

Section: Discussionmentioning

confidence: 95%

Identification of the causal agent of pistachio dieback in Australia

Facelli

Taylor²,

Scott

et al. 2005

Eur J Plant Pathol

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Symptoms associated with pistachio dieback in Australia include decline (little or no current season growth), xylem staining in shoots two or more years old, trunk l and limb lesions (often covered by black, superficial fungal growth), excessive exudation of resin, dieback and death of the tree. Bacteria belonging to the genus Xanthomonas have been suggested as the causal agent. To confirm the constant association between these bacteria and the disease syndrome, the absence of other pathogens and the identity of the pathogen, we performed a series of isolations and pathogenicity tests. The only microorganism consistently isolated from diseased tissue was a bacterium that produced yellow, mucoid colonies and displayed morphological and cultural characteristics typical of the genus Xanthomonas. Database comparisons of the fatty acid and whole-cell protein profiles of five representative pistachio isolates indicated that they all belonged to X. translucens, but it was not possible to allocate the isolates to pathovar. Pathogenicity tests on cereals and grasses supported this identification. However, KochÕs postulates have been only partially fulfilled because not all symptoms associated with pistachio dieback were reproduced on inoculated twoyear-old pistachio trees. While discolouration was observed, dieback, excessive resinous exudate and trunk and limb lesions were not produced; expression of these symptoms may be delayed, and long-term monitoring of a small number of inoculated trees is in progress.

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“…With view on the high yield losses observed across infected plants, Xtg resistance is of major concern for breeding of new Italian ryegrass cultivars. The currently applied approach is based on recurrent phenotypic selection; however, reoccurrence of susceptible individuals after several selection cycles indicates the need for a detailed understanding of underlying pathogenicity mechanisms, which can be exploited in targeted breeding for bacterial wilt resistance [6, 7]. …”

Section: Introductionmentioning

confidence: 99%

Comparative genomics of host adaptive traits in Xanthomonas translucens pv. graminis

et al. 2017

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Background Xanthomonas translucens pathovars differ in their individual host ranges among Poaceae. As the causal agent of bacterial wilt in Italian ryegrass (Lolium multiflorum Lam.), X. translucens pv. graminis (Xtg) is one of the most important bacterial pathogens in temperate grassland regions. The genomes of six Xtg strains from Switzerland, Norway, and New Zealand were sequenced in order to gain insight into conserved genomic traits from organisms covering a wide geographical range. Subsequent comparative analysis with previously published genome data of seven non-graminis X. translucens strains including the pathovars arrhenatheri, poae, phlei, cerealis, undulosa, and translucens was conducted to identify candidate genes linked to the host adaptation of Xtg to Italian ryegrass.ResultsPhylogenetic analysis revealed a tight clustering of Xtg strains, which were found to share a large core genome. Conserved genomic traits included a non-canonical type III secretion system (T3SS) and a type IV pilus (T4P), which both revealed distinct primary structures of the pilins when compared to the non-graminis X. translucens strains. Xtg-specific traits that had no homologues in the other X. translucens strains were further found to comprise several hypothetical proteins, a TonB-dependent receptor, transporters, and effector proteins as well as toxin-antitoxin systems and DNA methyltransferases. While a nearly complete flagellar gene cluster was identified in one of the sequenced Xtg strains, phenotypic analysis pointed to swimming-deficiency as a common trait of the pathovar graminis.ConclusionOur study suggests that host adaptation of X. translucens pv. graminis may be conferred by a combination of pathovar-specific effector proteins, regulatory mechanisms, and adapted nutrient acquisition. Sequence deviations of pathogen-associated molecular patterns (PAMPs), as observed for the pilins of the T4P and T3SS, are moreover likely to impede perception by the plant defense machinery and thus facilitate successful host colonization of Italian ryegrass.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3422-7) contains supplementary material, which is available to authorized users.

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Interactions Between Xanthomonas campestris pv. graminis Strains and Meadow Fescue and Italian Rye Grass Cultivars

Cited by 16 publications

References 12 publications

The noncanonical type III secretion system of Xanthomonas translucens pv. graminis is essential for forage grass infection

The noncanonical type III secretion system of Xanthomonas translucens pv. graminis is essential for forage grass infection

Identification of the causal agent of pistachio dieback in Australia

Comparative genomics of host adaptive traits in Xanthomonas translucens pv. graminis

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