Katherine F. LoBuglio

Phylogenetic analysis of two ribosomal DNA regions indicates multiple independent losses of a sexual Talaromyces state among asexual Penicillium species in subgenus Biverticillium

ABSTRACTNucleotide sequences were obtained from the mitochondrial small subunit ribosomal DNA, and the nuclear ribosomal DNA region containing the internal transcribed spacers and 5.8S ribosomal RN...

Two Sibling Species of the Botrytis cinerea Complex, transposa and vacuma, Are Found in Sympatry on Numerous Host Plants

ABSTRACT Strains of Botrytis cinerea (the anamorph of Botryotinia fuckeliana) were collected from 21 different plant species around vineyards in the Champagne region (France). Strains were analyzed using three new polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) markers that were found by SWAPP (sequencing with arbitrary primer pairs), in addition to 15 other markers (PCR-RFLP, transposable elements, and resistance to fungicides). The markers revealed a high degree of genetic diversity and were used to investigate population structure. The two sympatric species transposa and vacuma, previously identified on grapes in these vineyards, were also detected on many of the plant species sampled. A new type of strain was also detected, having only the transposable element Boty. We did not detect any differentiation between strains from different organs or locations, but the prevalences of transposa and vacuma were significantly different on the different host plants. Fungicide resistance frequencies were significantly different in transposa and vacuma species. This study confirms that B. cinerea is a complex of sibling species and shows that the sibling species occur sympatrically on many host plants. However, the two species seemed to have different pathogenic behaviors. These findings contradict the traditional view of B. cinerea as a clonal population without specialization.

Recombination and genetic differentiation in the mycorrhizal fungus Cenococcum geophilum Fr.

Population genetic analyses of the mycorrhizal fungus Cenococcum geophilum were conducted to test for a clonal or recombining population structure. Multilocus genotypes based on polymorphisms in 9 loci, identified in this study by PCR-SSCP techniques, were obtained for two populations. Genotypic variation occurred on a fine scale because unique genotypes were identified at most every transect point, and in some cases occurred even within one soil sample (equivalent to about a 500 mL volume). The largest genet observed occurred over a 30 meter transect space. The two population genetic methods employed to distinguish between clonality and recombination, (1) Index of Association; and (2) “Parsimony Tree Length Permutation Test” (PTLPT), could not reject the null hypothesis of recombination in either population. Wrights Fst, as estimated by theta, was used to examine gene flow between the two populations based on allele frequencies. Two of the nine loci had theta values that were not significantly different from what one would expect for the null hypothesis of panmixia. However, the other seven loci were consistent with reduced gene flow. The theta value for the Fisher combined probability (combining all 9 loci) was significant and indicated that there was genetic differentiation between these two populations.

Comparison of ribosomal DNA ITS regions among geographic isolates of Cenococcum geophilum

Cenococcum geophilum is an ecologically important mycorrhizal fungus with a global distribution and a wide host range. It has been difficult to study since it forms only sterile mycelia and, occasionally, sclerotial bodies. Because of its lack of morphological variability, its taxonomy and phylogenetic origins have until recently remained unclear. To better understand the genetic variation and environmental adaptability of C. geophilum, a molecular phylogeny was constructed based on the nuclear ribosomal DNA internal transcribed spacers (ITS1 and ITS2) of 69 isolates from various hosts and habitats. The results suggest DNA sequence conservation in the ITS regions. Considering its broad geographic and host range, this ITS conservation was unexpected. Our data imply that the ITS2 region is under evolutionary pressure to maintain the RNA secondary structure (similar to the pressure on the CgSSU introns) involved in the post-transcriptional processing of rRNA. Also, C. geophilum has very short ITS regions, thus limiting the number of mutable sites. This limited ITS variability suggests a recent radiation of C. geophilum, having been geographically distributed by a variety of efficient processes. C. geophilum appears to be a single taxonomic entity, possibly a single species. Therefore, it is an extremely adaptable, as well as ecologically valuable, taxon.

Messenger RNA intron in the nuclear 18s ribosomal RNA gene of deuteromycetes.

Introns within messenger RNA genes have characteristic border sequences and a conserved region near the 3′ end of the intron. All are involved in splicing to produce the mature mRNA. Introns in ribosomal RNA genes have less well-defined borders and contain no internal conservation. We report here mRNA-type introns located near the 3′ end of the 18s rRNA genes of the deuteromycetes Phialophora americana and Cenococcum geophilum. Inserted sequences of various sizes have also been located at the same point in several other deuteromycete species.

Independent origins of the synnematous Penicillium species, P. duclauxii, P. clavigerum, and P. vulpinum, as assessed by two ribosomal DNA regions

Nucleotide sequences from the mitochondrial small rRNA gene and the nuclear rDNA region containing the internal transcribed spacers and 5.8S rRNA gene were determined for three synnematous Penicillium species, P. clavigerum, P. duclauxii and P. vulpinum . Trees were generated from aligned sequence data of each rDNA region using parsimony methods. The tree topologies for each rDNA region, and for the combined data set, were identical in all statistically significant branches as assessed by bootstrap analysis. Both rDNA regions support the separation of the two meiotic genera with mitotic Penicillium states, Talaromyces and Eupenicillium , into two distinct evolutionary lineages within the Eurotiales. Phylogenetic analysis demonstrated that two distinct phylogenetic origins account for the evolution of the synnematous Penicillium species examined. Penicillium clavigerum , and P. vulpinum have phylogenetic affinities with the meiotic genus Eupenicillium , while P. duclauxii is related to the meiotic genus Talaromyces and the mitotic genus Penicillium subgenus Biverticillium .

A Glomerella species phylogenetically related to Colletotrichum acutatum on Norway maple in Massachusetts

A fungus isolated from Norway maple (Acer platanoides) in the Boston, Massachusetts, area was determined to be a species of Glomerella, the teleomorph of Colletotrichum acutatum. Pure cultures of the fungus were obtained from discharged ascospores from perithecia in leaf tissue. This fungus was determined to be homothallic based on the observation of perithecial development in cultures of single-spore isolates grown on minimal salts media and with sterile toothpicks. A morphological and molecular analysis was conducted to determine the taxonomic position of this fungus. Parsimony analyses of a combined nucleotide dataset of the ITS and LSU rDNA region, and of the D1–D2 LSU rDNA region, indicated that this species has phylogenetic affinities with Colletotrichum acutatum, C. acutatum f. sp. pineum, C. lupini, C. phormii and G. miyabeana. These results are significant because C. acutatum has not been reported on Acer platanoides. In addition the consistent presence of perithecia on leaf tissue and in culture is unusual for Colletotrichum, suggesting that the teleomorphic state is important in the life cycle of this fungus.

Placement of Medeolaria farlowii in the Leotiomycetes, and comments on sampling within the class

Medeolaria farlowii, an ascomycetous parasite of Medeola virginiana, has been included as the only member of the family Medeolariaceae and order Medeolariales. Its assignment within the Ascomycota has been problematic due to the lack of distinctive ascomatal form and ascus morphology. Asci are formed in a loosely organized hymenium on hypertrophic portions of Medeola virginiana stems. Phylogenetic analyses of nuclear 5.8S, large subunit, and small subunit rDNA gene sequences place M. farlowii in the Leotiomycetes with parsimony, Bayesian, and maximum likelihood analyses, but its position within this class remains unresolved. In general, limited taxon and gene sampling in the Leotiomycetes hampers placement of taxa within this class. A survey of available sequence data in the Leotiomycetes is given, and the implication for phylogenetic studies within the class is discussed. Medeolaria farlowii should be treated as a monotypic genus in the monotypic order Medeolariales, class Leotiomycetes.

The Caloscyphaceae (Pezizomycetes, Ascomycota), with a new genus

The family Caloscyphaceae with a single genus, Caloscypha, has been considered to include a single species, C. fulgens. Study of an overlooked second species, Caloscypha incarnata from North Africa and Italy, using SSU, LSU rDNA, and morphology allows placement of this species in a new genus, Kallistoskypha, in the Caloscyphaceae. This fungus is found in association with Eucalyptus species. The species was recently redescribed from Spain under the name Marcelleina parvispora. Caloscypha fulgens, the type species of the genus Caloscypha, shows sequence variation from across its range.

Clarification of Peziza fimeti with notes on P. varia collections on dung

The smooth-spored species inhabiting dung, mainly of the Peziza fimeti group, were studied morphologically and through ITS sequence comparison. The results established that Peziza varia is also able to fruit on dung, clarifying a long-standing situation regarding two conflicting interpretations given in P. fimeti literature.