Molecular Approaches to Differentiate Subpopulations or Formae speciales of the Fungal Phytopathogen Microbotryum violaceum

Perlin, Michael H.; Hughes, Carolyn F.; Welch, Jacqueline; Akkaraju, S.; Steinecker, David; Kumar, Ashima V.; Smith, Brian J.; Garr, Stephanie S.; Brown, Scott A.; Ando, Tedros

doi:10.1086/297469

Cited by 28 publications

(18 citation statements)

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“…Previous work has indicated that M. violaceum strains from different caryophyllaceous hosts are most often host‐specific (Shykoff et al 1999). Genetic analyses have also revealed that anther‐smut strains from different host species are geneticically differentiated (Perlin et al 1997, Shykoff et al 1999, Bucheli et al 2000, Hood et al 2003, Van Putten et al 2004). In my inoculation experiment, however, there were no differences in infectivity between the two populations of M. violaceum originating from the sympatric populations of L. alpina and S. rupestris.…”

Section: Discussionmentioning

confidence: 99%

Disease dynamics, host specificity and pathogen persistence in isolated host populations

Carlsson-Granér¹

2006

Oikos

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Carlsson-Granér, U. 2006. Disease dynamics, host specificity and pathogen persistence in isolated host populations. Á/ Oikos 112: 174 Á/184.In situations where populations of related host species grow sympatrically but isolated from other populations of either host, cross-species disease transmission can have large influences on disease dynamic and patterns of pathogen persistence. This study examined host Á/pathogen dynamics and the degree of host-specificity in the anthersmut fungus Microbotryum violaceum at a site where two of its host species, Lychnis alpina and Silene rupestris, grew in adjacent patches which were located at large distances from the nearest intra-specific host and pathogen populations. In a fieldstudy carried out over a four-year period in the sympatric populations, the two host species exhibited broadly parallel patterns of mortality and recruitment across years, although higher rates of mortality and infection, and larger fluctuations in numbers of plants, were seen in the S. rupestris population. However, when the frequency of disease in the populations was taken into account, disease transmission rates were relatively similar in the two hosts. In a reciprocal cross-inoculation experiment, there were no differences in infectivity between the two fungal populations on progeny of the two hosts from the sympatric populations indicating that cross-species disease transmission is possible. Patterns of infectivity on plants from the sympatric populations and allopatric populations of each host indicated the occurrence of a host shift in M. violaceum from L. alpina onto S. rupestris at the sympatric site. Results from a population model, parameterised with the demographic data from the two hosts, demonstrated that some cross-species disease transmission could increase the frequency of disease and lower the threshold level of pathogen persistence in populations. The population model also suggests that high levels of juvenile infection, as observed in both hosts, may increase the probability of pathogen persistence in local populations, especially in the more short-lived S. rupestris. U.

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Section: Discussionmentioning

confidence: 99%

Disease dynamics, host specificity and pathogen persistence in isolated host populations

Carlsson-Granér¹

2006

Oikos

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“…Assuming a random sampling of the genome, the probability of repeatedly obtaining the same locus by chance alone is small, roughly equal to the percent coverage of the sex chromosome (3 to 4%) and the autosomes (0.4%), respectively, for sequences from these sources. Additionally, by excluding rDNA and tubulin genes that have been used for phylogeny reconstruction (Perlin et al, 1997;Freeman et al, 2002), only 56 DNA sequences from M. violaceum (averaging 356 bp in length) had been deposited by other researchers into the NCBI databases. Ten of the cloned fragments from the current study matched one or more of these previously deposited sequences, further illustrating the high level of redundancy within the M. violaceum genome.…”

Section: Discussionmentioning

confidence: 99%

Repetitive DNA in the automictic fungus Microbotryum violaceum

Hood

2005

Genetica

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The small genomes of fungi are expected to have little repetitive content other than rDNA genes. Moreover, among asexual or highly selfing lineages, the diversity of repetitive elements is also expected to be very low. However, in the automictic fungus Microbotryum violaceum, a very large proportion of random DNA fragments from the autosomes and the fungal sex chromosomes are repetitive in nature, either as retrotransposon or helicase sequences. Among the retrotransposon sequences, examples were found from each major kind of elements, including copia, gypsy, and non-LTR sequences. The most numerous were copialike elements, which are believed to be rare in fungi, particularly among basidiomycetes. The many helicase sequences appear to belong to the recently discovered Helitron type of transposable elements. Also, sequences that could not be identified as a known type of gene were also very repetitive within the database of random fragments from M. violaceum. The differentiated pair of fungal sex chromosomes and suppression of recombination may be the major forces determining the highly repetitive content in the small genome of M. violaceum.

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“…However, cross‐inoculation experiments dating back to the early 20th century (Zillig, 1921; Goldschmidt, 1928) and recent molecular phylogenetic studies (Garr et al. , 1997; Perlin et al. , 1997; Bucheli et al.…”

Section: Introductionmentioning

confidence: 99%

Maximized virulence in a sterilizing pathogen: the anther‐smut fungus and its co‐evolved hosts

Sloan

Giraud

Hood

2008

J of Evolutionary Biology

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Host sterilization is a common feature of sexually transmitted diseases (STDs). Because host reproductive failure may free up resources for pathogen reproduction and transmission, theory predicts that selection on sterilizing pathogens will favour maximum virulence (i.e. complete sterilization). We examined patterns of infection in sexually transmitted anther‐smut fungi (Microbotryum) on four of their host species in the Caryophyllaceae. Using controlled fungal matings and experimental inoculations, we compared disease expression in inoculations ranging from host‐specific pathogens to hybrids and cross‐species treatments. Our data support the existence of host‐specific sibling species within the genus Microbotryum based on a low infection rate from cross‐inoculations and reduced fitness for hybrid pathogens. These patterns of host specificity and reproductive isolation, however, were not absolute. We did observe some successful cross‐species and hybrid infections, but the expression of disease was frequently incomplete, including only partial host sterilization and the failed dehiscence of pathogen spores. The prevalence of these maladapted disease phenotypes may greatly inhibit the emergence of novel host pathogen combinations. Infections by hybrid pathogen genotypes were intermediate, in terms of both infection rate and the normality of disease symptoms, between host‐specific and cross‐inoculated pathogens. In addition, the frequency with which hybrid and cross‐inoculated anther‐smut pathogens were able to infect but not sterilize new hosts supports the prediction that sterilizing STDs are under selection to maximize virulence in natural populations.

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Molecular Approaches to Differentiate Subpopulations or Formae speciales of the Fungal Phytopathogen Microbotryum violaceum

Cited by 28 publications

References 0 publications

Disease dynamics, host specificity and pathogen persistence in isolated host populations

Disease dynamics, host specificity and pathogen persistence in isolated host populations

Repetitive DNA in the automictic fungus Microbotryum violaceum

Maximized virulence in a sterilizing pathogen: the anther‐smut fungus and its co‐evolved hosts

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