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Department of Plant Pathology, Iowa State University, Ames, Iowa, 50011
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSTAXONOMYDISCUSSIONLITERATURE CITED |
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Parsimony analysis of sequences of the internal transcribed spacer region of the nuclear rDNA and partial sequences of the large subunit (LSU) place four anamorphic Chalara species as a monophyletic grouping within the teleomorph genus Ceratocystis. Chalara ovoidea, Ch. thielavioides, Ch. populi, and Ch. elegans (synanamorph: Thielaviopsis basicola) form aleurioconidia typical of the anamorph genus Thielaviopsis, to which the species are transferred. Three of these species (T. ovoidea, T. thielavioides, and T. populi) are morphologically similar to each other but are shown to be distinct by rDNA sequences. The anamorphic genera Chalaropsis and Hughesiella are considered synonyms of Thielaviopsis. Thielaviopsis punctulata, which forms aleurioconidia singly, is shown to be the anamorph of Ce. radicicola. The respective anamorphs for Ce. coerulescens, Ce. fagacearum, and Ce. eucalypti, which lack aleurioconidia, are also transferred to the amended genus Thielaviopsis as T. ungeri, T. quercina, and T. eucalypti. Although Ch. australis and Ch. neocaledoniae do not form aleurioconidia, they are placed in Thielaviopsis based on their endoconidial state and clear affinities to Ceratocystis eucalypti. Three apparently asexual Ambrosiella species belong in the Ce. moniliformis clade based on LSU rDNA sequences, but the cultures available are not suitable for detailed morphological study, and these species are not transferred to Thielaviopsis.
Key words: Ascomycetes, Ceratocystis paradoxa, rDNA, Thielaviopsis paradoxa
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSTAXONOMYDISCUSSIONLITERATURE CITED |
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). These four plant pathogenic species produce thick, dark-walled aleurioconidia (Figs. 1–6
) in addition to endoconidia from phialidic conidiophores. Ceratocystis sensu stricto is a monophyletic genus of insect dispersed, plant pathogenic fungi, and all Ceratocystis species have Chalara anamorphs (de Hoog and Scheffer 1984
, Harrington 1981, 1987
, Paulin and Harrington 2000
, Witthuhn et al 1999
). Aside from members of the Ce. coerulescens (Münch) Bakshi complex, Ce. moniliformis (Hedgecock) Moreau, and Ce. fagacearum (Bretz) Hunt, most species of Ceratocystis also produce thick-walled aleurioconidia from the tips of specialized hyphae. These aleurioconidia are produced in chains (synanamorph = Thielaviopsis Went) or singly (synanamorph = Chalaropsis Peyr.). Three apparently asexual symbionts of ambrosia beetles (Ambrosiella xylebori Brader ex v. Arx et Hennebert, A. hartigii Batra, and A. ferruginea (Math.-Käärik) Batra) also have affinities to Ceratocystis (Cassar and Blackwell 1996
), but they apparently do not produce aleurioconidia (Batra 1967
).
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) has gone uncontested until recently, when Chalara was found to be polyphyletic using partial small subunit (SSU, 18S) and large subunit (LSU, 28S) nuclear rDNA sequences (Paulin and Harrington 2000
). The genus Chalara is typified by Chalara fusidioides (Cda.) Rabenh., a saprobe with deep-seated phialides that produces enteroblastic conidia by ring-wall building (Minter et al 1982, 1983
, Nag Raj and Kendrick 1975, 1993
). Most of the studied Chalara species without known teleomorphs were shown to have Leotialian affinities using rDNA sequences (Paulin and Harrington 2000
). The description and biology of Ch. fusidioides, especially its slow growth rate on agar media (Nag Raj and Kendrick 1975
), suggest that it may also belong within the Leotiales. Thus, Chalara does not appear to be an appropriate name for anamorphic species with Ceratocystis affinities.
The genus Thielaviopsis is based on Thielaviopsis ethacetia Went (Nag Raj and Kendrick 1975
, Went 1893
), which was later recognized as a synonym of Thielaviopsis paradoxa (de Seynes) Höhn, the anamorph of Ceratocystis paradoxa (Dade) Moreau. Went (1893)
gave the generic diagnosis for Thielaviopsis as "Hyphae steriles repentes, subhyalinae, fertiles simplices, septatae. Conidia dimorpha, majora catenulata, ovata, fusca; minora cylindracea, hyalina, ex interiore hypharum catenulatim generata et ex apice exsilientia." Thus, his concept of the genus included conidia of two types, endoconidia from phialides and larger, pigmented aleurioconidia in chains at the tips of specialized hyphae. Peyronel (1916)
erected the genus Chalaropsis, using the type species Chalaropsis thielavioides, for species with aleurioconidia produced singly. Thielaviopsis basicola (Berk. et Br.) Ferr (synanamorph = Chalara elegans) produces aleurioconidia from a basal sporogenous cell, and this conidium undergoes division into an aleurioconidial chain that fragments into individual barrel-shaped spores (Riggs and Mims 2000
).
We used parsimony analysis of sequences from the large subunit and internal transcribed spacer regions (ITS) of the nuclear ribosomal DNA operon to examine the phylogenetic placement of anamorphic species with Ceratocystis affinities. We tested the hypothesis that four of these Chalara species form an asexual lineage within Ceratocystis. We also used morphological comparisons to determine if three of these are distinct species or if they are a single species. The genus Thielaviopsis is amended, and Chalara species with Ceratocystis affinities are transferred to Thielaviopsis.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSTAXONOMYDISCUSSIONLITERATURE CITED |
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PCR, DNA sequencing, and RFLP analysis –
A portion of the LSU and the internal transcribed spacer regions (ITS) of the nuclear rDNA were amplified and sequenced for Chalara, Ambrosiella, and Ceratocystis species. The primers (ITS1-F, ITS-4, LR3, LR5, and LROR) and protocols for amplification and sequencing were as described by Paulin and Harrington (2000)
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Partial sequences of the LSU gene were obtained from 10 species within the genus Ceratocystis and six species within Chalara (Table I
). The outgroup taxa Glomerella phacidiomorpha (Cesati) Petrak and Petriella sordida Barron et Gilman are closely related to Ceratocystis (Paulin and Harrington 2000
). The sequences were manually aligned, but 40 of the 590 LSU characters, including gaps, were ambiguously aligned and eliminated before parsimony analysis. After excluding the ambiguously aligned characters, the largest insertion/deletion (indel) within the LSU data set was one base pair.
Sequences of the ITS and the 5.8S rDNA from four species of Ceratocystis were compared to those of five species of Chalara (Ch. ovoidea, Ch. elegans, Ch. thielavioides, Ch. populi, and Ch. punctulata Hennebert). Among the Ceratocystis species, only the ITS sequences of Ce. moniliformis, Ce. adiposa, Ce. radicicola and Ce. paradoxa could be reasonably aligned with those of the five Chalara species. Ceratocystis moniliformis was used as the outgroup taxon because it is distinct molecularly (LSU sequences and MAT-2 sequences, data not shown) and morphologically (hat-shaped ascospores and no aleurioconidia) from the Chalara species. The sequences were manually aligned, but 69 of the 483 ITS characters, including gaps, were ambiguously aligned and, therefore, eliminated before parsimony analysis. After excluding ambiguously aligned characters, the largest indel within the ITS data set was two base pairs.
In both data sets, gaps were treated as a fifth character. Only parsimony informative sites were used in the phylogenetic analyses (PAUP 4.04b, Swofford 1998
). Maximum parsimony heuristic searches were performed with all characters having equal weight, starting trees were obtained via stepwise addition, and tree-bisection-reconnection was used. Robustness of the internal branches of the tree was evaluated by 1000 bootstrap replications using heuristic searches (Felsenstein 1985
). Decay indices (Bremer 1988
) were calculated using AutoDecay version 4.0 (Eriksson 1998
). Trees were rooted at the internal node with basal polytomy.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSTAXONOMYDISCUSSIONLITERATURE CITED |
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), and the other four species are in a distinct clade within Ceratocystis (Fig. 7
). Eighteen equally most parsimonious trees of 185 steps were derived from analysis of the 63 parsimony informative positions of the LSU data set. The consistency (CI), homoplasy (HI), retention (RI), and rescaled consistency (RC) indices were 0.8000, 0.2000, 0.8490, and 0.6792, respectively. Based on LSU data, the clade of four Chalara species (Ch. ovoidea, Ch. thielavioides, Ch. populi, and Ch. elegans) was not supported by bootstrap analysis but had a decay value of d1 and was found in each of the 18 most parsimonious trees. Ambrosiella species were placed within the strongly supported Ce. moniliformis clade with Ce. adiposa (Butler) Moreau and Ce. fagacearum, confirming the SSU rDNA findings of Cassar and Blackwell (1996)
. When gaps were treated as missing data, 18 trees of 174 steps were found, and these trees had the topology of the trees in which gaps were treated as a fifth character.
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) of the LSU data set was also performed, and a tree with a topology only slightly different from Fig. 7
was produced (Fig. 8
). As in parsimony analysis, the four Chalara species (Ch. ovoidea, Ch. thielavioides, Ch. populi, and Ch. elegans) grouped together in the neighbor joining analysis, and there was support for the Ce. fimbriata, Ce. coerulescens, Ce. paradoxa and Ce. moniliformis clades. The Ce. paradoxa clade was sister to the Ce. coerulescens clade in the neighbor joining tree, as opposed to being sister to the Ce. moniliformis clade in parsimony analysis (Fig. 7
), but there was little resolution of the relationships among the five major clades of Ceratocystis, except that the Ce. fimbriata complex was basal to the genus in both parsimony and neighbor joining analyses.
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), Ce. fimbriata complex and Ce. fagacearum (Witthuhn et al 1999
) could not be unambiguously aligned with the ITS sequences of the four Chalara species and, therefore, were not used in parsimony analysis. Two equally most parsimonious trees of 122 steps were derived from analysis of the 47 parsimony informative positions of the ITS data set. The CI, HI, RI and RC indices were 0.8934, 0.1066, 0.8960, and 0.8005, respectively. Strong bootstrap support was found for the grouping of the "asexual Chalara clade" (Fig. 9
), and this branch had a decay index of d8. Ceratocystis radicicola (Bliss) Moreau and Ce. paradoxa had ITS sequences that were similar to those of the Chalara clade. Chalara punctulata was morphologically similar to the anamorph of Ce. radicicola, and these species had identical ITS sequences (Fig. 9
). When gaps were treated as missing data, two trees of 97 steps were found, and the trees were identical to those found when gaps were treated as a fifth character. A neighbor joining analysis was performed on the ITS data, and a tree was produced that was identical to that shown in Fig. 9
.
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: 9–19 x 7.5–18 µm (ratio = 1.15/1) and 6.5–32 x 2.5–6.5 µm (ratio = 3.5/1), respectively. Peyronel (1916)
reported that Ch. thielavioides has aleurioconidia 10–20 x 8–15 µm (ratio = 1.3/1) and endoconidia 8–55 x 3–4.5 µm (ratio = 7.8/1).
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). We found aleurioconidia of Ch. ovoidea (isolates C1375 and C1376) to be 8–16 x 4–10 µm, with length to width ratios of 1.6–1.8/1, and endoconidia were 10–21 x 2–4 µm, with length to width ratios of 4.8–5.3/1, similar to measurements reported by Nag Raj and Kendrick (1975)
: 7.5–14 x 6–11 µm (1.25/1) and 5–22 x 2.5–5 µm (3.3/1), respectively.
Kiffer and Delon (1983)
reported that Ch. populi, when compared to Ch. ovoidea, has longer phialides on branched conidiophores. They reported aleurioconidia to be 6.7–12 x 6–9 µm and endoconidia to be 6–18 x 2.2–3.8 µm, similar to those of Ch. ovoidea. We also found that aleurioconidia of Ch. populi are similar in width to those of Ch. ovoidea (Figs. 2, 3 ).
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TAXONOMY |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSTAXONOMYDISCUSSIONLITERATURE CITED |
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), is also considered a synonym. Thielaviopsis Went, Arch. voor de Java Suekerr., p 4. 1893, emend. Paulin, Harrington, et McNew
Thick, dark-walled aleurioconidia present or absent, produced either singly or in chains upon specialized hyphae. Chalara-like conidia are produced by ring wall building within phialides, extruded in chains, cylindrical, remaining hyaline or becoming thick-walled and dark. When known, teleomorphs are placed in Ceratocystis.
Type: Thielaviopsis paradoxa (de Seynes) Höhn., Hedwigia 43: 295. 1904.
Sporoschisma paradoxum de Seynes, Recherches pour Servir à d'Histoire Naturelle des Végétaux Inférieurs, 3: 30. 1886.
Chalara paradoxa (de Seyenes) Sacc, Sylloge Fung., 10: 595. 1892.
Ceratostomella paradoxa Dade, Trans. Br. Mycol. Soc., 13: 191. 1928.
Ophiostoma paradoxum (Dade) Nannf., Svenska Skogsfor. Tidskr. 32: 408. 1934.
Endoconidiophora paradoxa (Dade) Davidson, J. Agric. Res. 50: 802. 1935. Thielaviopsis australis (Kile) Paulin, Harrington, et McNew, comb. nov.
Chalara australis Kile, Austr. J. Bot. 35: 7. 1987. Thielaviopsis basicola (Berk. et Br.) Ferr., Flora Italica Cryptogama. Pars. I: Fungi, Hyphales, Tuberculariaceae-Stilbaceae. Fasc. 6: 113. 1910.
Torula basicola Berk. et Br., Ann. Mag. Nat. Hist., ser. 2, 13: 456. 1854.
Thielaviopsis eucalypti (Z.Q. Yuan et Kile) Paulin, Harrington, et McNew, comb. nov.
Chalara eucalypti Z.Q. Yuan et Kile, Mycol. Res. 100: 573. 1996.
Thielaviopsis euricoi (Bat. et Vital) Paulin, Harrington, et McNew, comb. nov.
Hughesiella euricoi Bat. et Vital, Anais. Soc. Biol. Pernamb., 14: 42. 1956. Thielaviopsis neocaledoniae (Dadant ex Kiffer et Delon) Paulin, Harrington, et McNew. comb. nov.
Chalara neocaledoniae Dadant ex Kiffer et Delon, Mycotaxon 18: 166. 1983.
Thielaviopsis neocaledoniae Dadant, nom. inval., Art. 36, 37. Rev. Gén. Bot. 57: 176. 1950. Thielaviopsis ovoidea (Nag Raj et Kend.) Paulin, Harrington, et McNew, comb. nov.
Chalara ovoidea Nag Raj et Kend., A Monograph of Chalara and Allied Genera. p. 127. 1975. Thielaviopsis populi (Veldeman ex Kiffer et Delon) Paulin, Harrington, et McNew, comb. nov.
Chalara populi Veldeman ex Kiffer et Delon, Mycotaxon 18: 171. 1983.
Chalaropsis populi Veldeman, nom. inval. Art. 36, 37. Meded. Fak. Land. Wet. Gent 36: 1001. 1971. Thielaviopsis punctulata (Hennebert) Paulin, Harrington, et McNew, comb. nov.
Chalaropsis punctulata Hennebert, Anton. Leeuw. 33: 334. 1967.
Ceratostomella radicicola Bliss, Mycologia 33: 468. 1941. Thielaviopsis quercina (Henry) Paulin, Harrington, et McNew, comb. nov.
Chalara quercina Henry, Phytopathology 34: 631. 1944.
Endoconidiophora fagacearum Bretz, Phytopathology 42: 437. 1952. Thielaviopsis thielavioides (Peyr.) Paulin, Harrington, et McNew, comb. nov.
Chalaropsis thielavioides Peyr., Staz. Sper. Agr. It. 49: 596. 1916
Chalara thielavioides (Peyr.) Nag Raj et Kend., A Monograph of Chalara and Allied Genera. p. 136. 1975.
Thielaviopsis ungeri (Sacc.) Paulin, Harrington, et McNew, comb. nov.
Chalara ungeri Sacc., Sylloge Fung., 4: 336. 1886.
Endoconidiophora coerulescens Münch, Naturw. Z. Land. Forstw. 5: 54. 1907.
Ophiostoma coerulescens (Münch) Nannf., Svensa Skogsfor. Tidskr. 32: 408. 1934. |
DISCUSSION |
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, Witthuhn et al 2000
), Ce. moniliformis, and Ce. fagacearum have apparently lost the ability to produce aleurioconidia, and none of these species are known to be soilborne. Four asexual species are the only known plant pathogenic Chalara species that produce aleurioconidia, either singly (T. thielavioides, T. populi, T. ovoidea) or in chains (T. basicola), and they group as an asexual, monophyletic lineage within Ceratocystis based on rDNA sequences. Analysis of DNA sequences from a portion of the MAT-2 gene also groups these Thielaviopsis species as a monophyletic lineage (unpubl). These four Thielaviopsis species appear to be reproductively isolated, soilborne, root pathogens that are no longer dependent upon insects for dispersal, and it is possible that the four species are derived from a common asexual ancestor. The ITS sequences of T. thielavioides, T. ovoidea and T. populi isolates did not clearly delineate these species, but minor morphological differences suggest they are distinct species. Thielaviopsis ovoidea and T. populi may be recently derived species in the T. thielavioides complex.
Two other asexual species, T. australis and T. neocaledoniae, have no known teleomorph. However, only one isolate of T. neocaledoniae is available, and all available isolates of T. australis are of a single mating type (Harrington et al 1998
). Both T. australis and T. neocaledoniae will form sterile perithecia and aborted ascospores when paired with strains of the opposite mating type of Ce. eucalypti or Ce. virescens, respectively (Harrington et al 1998
). Thus, teleomorphs of T. australis and T. neocaledoniae may yet be found.
Three asexual Ambrosiella species (A. ferruginea, A. hartigii, and A. xylebori) form conidia at the tips of hyphal branches that are fed upon by ambrosia beetle symbionts (Batra 1967
). Using partial sequences of the small subunit rDNA, Cassar and Blackwell (1996)
placed these three Ambrosiella species within Ceratocystis, while six other Ambrosiella species were placed in the Ophiostomatales, indicating that the genus Ambrosiella is polyphyletic. Using partial sequences of the large subunit rDNA, we show that the three Ambrosiella species, A. ferruginea, A. hartigii, and A. xylebori, are placed within the Ce. moniliformis group, with A. ferruginea near Ce. fagacearum, and A. xylebori (the type species for Ambrosiella) and A. hartigii closely related to Ce. adiposa. A close examination of the conidia of these three Ambrosiella species may indicate a similarity to the endoconidia of their Ceratocystis relatives.
Chalaropsis punctulata, found on the roots of Lawsonia inermis by Hennebert (1967)
, was determined by Nag Raj and Kendrick (1975)
to be morphologically similar to the anamorph of Ce. radicicola. Comparison of ITS sequences showed no difference between Chalaropsis punctulata and Ce. radicicola, and isolate C1631 from the holotype of Ch. punctulata successfully mated with an isolate of Ce. radicicola in our tests (unpubl). Ceratocystis paradoxa, a close relative to Ce. radicicola, produces aleurioconidia in chains, so the distinction between aleurioconidia produced in chains (T. paradoxa) and aleurioconidia produced singly (Chalaropsis punctulata) appears trivial at the genus level, and we have synonymized Chalaropsis with Thielaviopsis.
There was some minor variation in LSU and ITS sequences among isolates of T. basicola and T. thielavioides. Punja and Sun (1999)
saw substantial variation in RAPD markers among isolates of T. basicola, and they speculated that genetically distinct strains of T. basicola may be adapted to specific hosts. Hammond (1935)
reported on a strain of T. thielavioides that appeared to have adapted to peach (Prunus persica). The morphological and genetic variation found in T. thielavioides suggest that T. thielavioides may also be comprised of host specialized forms, perhaps in the process of speciation.
Other described Thielaviopsis species warrant further study. Thielaviopsis wallemiaeformis Dom. et Ihn. (Dominik and Ihnatowicz 1975
) was considered an invalid name by Kiffer and Delon (1983)
. Thielaviopsis abuensis Chouhan et Panwar (Chouhan and Panwar 1980
) appears morphologically similar to T. basicola. Sugiyama (1968)
described Chalaropsis thielavioides var. ramosissima from buried plant material and distinguished it from T. thielavioides var. thielavioides based on more elongated and larger aleurioconidia. Our examination of the isolate from the holotype of var. ramosissima (C1630) did not reveal a distinction in morphology between var. ramosissima and var. thielavioides, and we have synonymized these varieties.
Our attempts to produce perithecia through pairings of different isolates of T. basicola and T. thielavioides have consistently failed, though other Ceratocystis species readily form perithecia and ascospores on agar media. From the data presented here, it appears that loss of the sexual state has occurred at least once in the evolution of Ceratocystis, and speciation appears to have occurred in this asexual lineage. Although delineation of species can be difficult for asexual fungi (Harrington and Rizzo 1999
), minor morphological characters separate T. ovoidea and T. populi from T. thielavioides, and further speciation may be taking place in T. thielavioides and T. basicola.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Accepted for publication May 27, 2001.
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LITERATURE CITED |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSTAXONOMYDISCUSSIONLITERATURE CITED |
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Batra LR., 1967 Ambrosia fungi: a taxonomic revision and nutritional studies of some species Mycologia 59:979-1017
Bremer K., 1988 The limits of amino acid sequence data in angiosperm phylogenetic reconstruction Evolution 42:795-803
Cassar S, Blackwell M., 1996 Convergent origins of ambrosia fungi Mycologia 88:596-601
Chouhan JS, Panwar KS., 1980 A new species of synnematous Thielaviopsis Ind Phyto 33:503-505
de Hoog G, Scheffer R., 1984 Ceratocystis versus Ophiostoma: a reappraisal Mycologia 76:292-299
DeScenzo RA, Harrington TC., 1994 Use of (CAT)5 as a DNA-fingerprinting probe for fungi Phytopathology 84:534-540
Dominik T, Ihnatowicz A., 1975 Soil fungi from Eloka near Abidjan in equatorial West Africa Zesz Nauk Wyzsz Szk Szczec 50:13-27
Eriksson T., 1998 AutoDecay version 4.0 Stockholm University, Department of Botany. Program distributed by author
Felsenstein J., 1985 Confidence limits on phylogenies: an approach using the bootstrap Evolution 39:783-791
Hammond JB., 1935 The morphology, physiology and mode of parasitism of a species of Chalaropsis infecting nursery walnut trees J Pom Hort Sci 13:81-107
Harrington TC., 1981 Cycloheximide sensitivity as a taxonomic character in Ceratocystis Mycologia 73:1123-1129
Harrington TC., 1987 New combinations in Ophiostoma of Ceratocystis species with Leptographium anamorphs Mycotaxon 28:39-43
Harrington TC., Rizzo DM., 1999 Defining species in the fungi In: Worrall JJ, ed. Structure and dynamics of fungal populations. Dordrecht, The Netherlands: Kluwer Academic Press. p 43–70
Harrington TC., Steimel J, Kile G., 1998 Genetic variation in three Ceratocystis species with outcrossing, selfing and asexual reproductive strategies Eur J For Path 28:217-226
Harrington TC., Wingfield MJ., 1998 The Ceratocystis species on conifers Can J Bot 76:1446-1457
Hennebert GL., 1967 Chalaropsis punctulata, a new hyphomycete Anton Leeuw 33:333-340
Kiffer E, Delon R., 1983 Chalara elegans (Thielaviopsis basicola) and allied species II—Validation of two taxa Mycotaxon 18:165-174
Minter DW, Kirk PM, Sutton BC., 1982 Holoblastic phialides Trans Br Mycol Soc 79:75-93
Minter DW, Kirk PM, Sutton BC., 1983 Thallic phialides Trans Br Mycol Soc 80:39-66
Nag Raj TR, Kendrick WB., 1975 A monograph of Chalara and allied genera Waterloo, Ontario: Wilfrid Laurier University Press
Nag Raj TR, Kendrick WB., 1993 The anamorph as generic determinant in the holomorph: the Chalara connection in the ascomycetes, with special reference to the Ophiostomatoid Fungi In: Wingfield MJ, Seifert KA, Webber JF, eds. Ceratocystis and Ophiostoma: taxonomy, ecology and pathology. St Paul, Minnesota: American Phytopathological Society. p 71–74
Paulin AE, Harrington TC., 2000 Phylogenetic placement of anamorphic species of Chalara among Ceratocystis and other ascomycetes Stud Mycol 45:169-186
Peyronel B., 1916 Una nova malattia del lupino prodotta da Chalaropsis thielavioides Peyr. nov. gen. et nova sp Staz Sper Agr Ital 49:583-596
Punja ZK, Sun LJ., 1999 Morphological and molecular characterization of Chalara elegans (Thielaviopsis basicola) cause of black root rot on diverse plant species Can J Bot 77:1801-1812
Riggs W, Mims CW., 2000 Ultrastructure of chlamydospore development in the plant pathogenic fungus Thielaviopsis basicola Mycologia 92:123-129
Sugiyama J., 1968 Mycoflora in core samples from stratigraphic drillings in middle Japan. II. The taxonomic status of the genus Chalaropsis Peyronel (Hyphomycetes) J Fac Sci Tokyo Univ (sect 3) 1:29-48
Swofford DL., 1998 PAUP*: Phylogenetic Analysis Using Parsimony (* and Other Methods) Version 4 Sunderland, Massachusetts: Sinauer Associates
Went FA., 1893 Die ananaziekte van het suikerriet Meded Proefstn Suik-Riet W Java, V
Witthuhn RC, Wingfield BD, Wingfield MJ, Harrington TC., 1999 PCR- based identification and phylogeny of species of Ceratocystis sensu stricto Mycol Res 103:743-749
Witthuhn RC, Harrington TC, Steimel JP, Wingfield BD, Wingfield MJ., 2000 Comparison of isozymes, rDNA spacer regions, and MAT-2 DNA sequences as phylogenetic characters in the analysis of the Ceratocystis coerulescens complex Mycologia 92:447-545
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