Ribosomal, mitochondrial and amplified DNA polymorphisms in Verticillium albo-atrum pathogenic to hops, lucerne and other plants

Griffen, Alison M.; Bainbridge, Brian W.; Heale, J. B.

doi:10.1017/s0953756297003742

Cited by 14 publications

(24 citation statements)

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“…In V. albo-atrum, the alfalfa isolates were clearly separated from isolates of other hosts, in accordance with the generally accepted division of GrpI isolates into L and NL groups. The same genetic pattern of alfalfa isolates from North America and England supports earlier reports of host adaptation and clonal population of these isolates (Correll et al, 1988;Griffen et al, 1997).…”

Section: Discussionsupporting

confidence: 88%

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Genetic variability and virulence among Verticillium albo-atrum isolates from hop

2006

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Verticillium wilt, caused by Verticillium albo-atrum or V. dahliae, is an important disease of many worldwide crop species. In Europe, V. albo-atrum isolates infecting hop express different levels of virulence, inducing mild or lethal disease syndromes, and it is therefore an attractive model for studying the virulence of this pathogen. In this work, eleven amplified fragment length polymorphism (AFLP) primer combinations were used to analyze genetic variability among 55 V. albo-atrum hop isolates from four European hop growing regions, as well as isolates from other hosts and V. dahliae isolates. Cluster analysis divided V. albo-atrum and V. dahliae isolates into two well-separated groups. Within the V. dahliae cluster, isolates were separated without host specific grouping, although no host adapted isolates were included. In V. alboatrum, the alfalfa isolates were distinct from isolates of other hosts, where a high association with virulence was observed in hop and tomato isolates. All lethal hop isolates were genetically different from mild hop isolates. The lethal hop isolates from England and Slovenia expressed the same virulence phenotype, although they showed a different AFLP pattern. The mild hop isolates formed two subgroups, to which isolates clustered irrespective of geographical location. These data suggest multiple origins of V. albo-atrum hop isolates, and the possible appearance of new virulent isolates in the future in other hop growing regions.

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Section: Discussionsupporting

confidence: 88%

“…A comprehensive study of V. albo-atrum isolates from various hosts, including 35 hop isolates from England, was performed by Griffen et al (1997). Molecular analysis, using RFLPs of ribosomal DNA, polymorphism of mtDNA and amplified polymorphic DNA (APD), confirmed the genetic distinction of alfalfa isolates from isolates of other hosts.…”

Section: Introductionmentioning

confidence: 96%

Genetic variability and virulence among Verticillium albo-atrum isolates from hop

2006

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“…Recently, two conflicting proposals have been made to place isolates classified as V . alboatrum into ‘groups’[2, 13]. Robb et al [13] proposed placing the isolate Luc 2 and potato isolates similar to it into a Group 2 (with all other isolates as Group 1); their Group 2 is therefore equivalent to the Group 3 of Griffen et al [2].…”

Section: Discussionmentioning

confidence: 99%

“…However, if a plethora of apparently new and confusing sub‐taxa are to be avoided, it is imperative firstly, that it should be considered that isolates found to be distinct may be more correctly placed in existing taxa, and secondly, that isolates must be maintained pure and true to type. In the case of the wilt pathogen Verticillium alboatrum , it appears that the suggestion that two low pathogenicity isolates be considered as a distinct ‘Group 2’ of this species [1, 2] is now, pending further research, found to be incorrect and that these isolates should be placed in, or taxonomically close to, Verticillium psalliotae and/or Verticillium fungicola .…”

Section: Introductionmentioning

confidence: 99%

Taxonomic status of putativeVerticillum alboatrumisolates

Carder¹,

Barbara²

1999

FEMS Microbiology Letters

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Two fungal isolates, formerly classified as Verticillium alboatrum and proposed as forming the basis of a new sub-group ('Group 2') within the species, have been shown to be non-pathogenic to known hosts of V. alboatrum and, on the basis of molecular evidence, to be closely related to Verticillium psalliotae and Verticillium fungicola. We propose that the taxon V. alboatrum be confined to those closely related isolates, usually plant pathogenic and usually producing dark resting mycelium, referred to by other authors as Group 1. The only sub-specific groupings which appear valid (based on pathological and molecular evidence) comprise: (1) host-adapted isolates from lucerne; and (2) all other isolates.

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“…dahliae and V. d 6 0 -atrum was evaluated using PCR technology and exploiting variations in rRNA or mitochondrial rRNA genes (Griffen et al, 1997). Li et al (1994) used a pair of conserved PCR primers to amplify a region of the mitochondrial small rRNA gene.…”

Section: Several Current Problems In Our Understanding Ofmentioning

confidence: 99%

Nuclear rDNA phylogeny in the fungal genus Verticillium and its relationship to insect and plant virulence, extracellular proteases and carbohydrases

et al. 1999

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Phylogenetic relationships among 18 isolates in the genus Verticillium, representing 13 species of diverse econutritional groups (pathogens of insects, plants, mushrooms, nematodes and spiders, and saprobes), were examined by using sequences from the internal transcribed spacer (ITS) and small nuclear (NS) rRNA regions. The isolates were also assessed for their abilities to infect insect larvae (Galleria mellonella) and to cause necrosis in alfalfa (Medicago sativa), and for their proteolytic, chitinolytic and pectinolytic activities. The phylogenetic data suggested that Verticillium is polyphyletic in origin and is therefore a form genus. However, the phylogenetic tree supported the plant pathogens (V. dahliae, V. albo-atrum and V. nigrescens) as a clade. The alfalfa isolate of V. albo-atrum (isolate 595) was an interesting outlier to the main body of plant pathogens as it clustered with the insect pathogen V. indicum. Strains of V. lecanii and V. indicum were able to infect insects and are present in divergent groups in the consensus tree, suggesting that the ability to infect insects may have evolved independently many times. Similarly, the nematophagous Verticillium species appear to have evolved independently along several different routes and one isolate, V. chlamydosporium, was able to infect insects. V. albo-atrum, V. nigrescens and V. dahliae all produced high levels of enzymes capable of degrading pectin, a major component of plant cell walls. The ability to excrete pectinase was a broad indicator of the ability to produce lesions on alfalfa. In the plant pathogens, the functions of a broad-spectrum protease were assumed by trypsins which degrade Bz-AA-AA-Arg-NA substrates (Bz, benzoyl; AA, various amino acids; NA, p-nitroanilide). The insect pathogens and mushroom pathogen (V. fungicola) were characterized by production of high levels of subtilisin-like proteases active against a chymotrypsin substrate (succinyl-Ala,-Pro-Phe-NA) and the inability to clear pectin. The insect and mushroom pathogens, and several nematode pathogens, were distinguishable from the plant pathogens in their ability to produce chitinases.

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Ribosomal, mitochondrial and amplified DNA polymorphisms in Verticillium albo-atrum pathogenic to hops, lucerne and other plants

Cited by 14 publications

References 24 publications

Genetic variability and virulence among Verticillium albo-atrum isolates from hop

Genetic variability and virulence among Verticillium albo-atrum isolates from hop

Taxonomic status of putativeVerticillum alboatrumisolates

Nuclear rDNA phylogeny in the fungal genus Verticillium and its relationship to insect and plant virulence, extracellular proteases and carbohydrases

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