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Studies on evolution and systematics of the powdery mildew fungi
... Obligate biotrophism and host specialization in powdery mildews may have evolved with and adapted to specific angiosperm host species during a boom in host range and diversity 70 million years ago (Takamatsu 2018). This holds true for P. aphanis, as strawberry is its only reported host. ...
... Fungicide resistance in mildews of other pathosystems has been researched more extensively. Although these are different pathogen species affecting other crops, they are closely related to P. aphanis (Takamatsu 2018). ...
... While there are published reports of fungicide resistance in several powdery mildews in the US and internationally, this data cannot be directly applied to the current state of fungicide resistance in populations of P. aphanis in California. The causal agents of grape and cucurbit powdery mildews are close relatives to P. aphanis, but are not genetically identical (Takamatsu 2018). The studies conducted on P. aphanis provide excellent reference but cannot provide a full characterization of current disease and host plant resistance in California. ...
Strawberry powdery mildew, caused by Podosphaera aphanis, affects leaves, fruit, and runners of strawberry plants. Infected leaves have reduced photosynthetic capability and infected fruit become unmarketable. Both of these factors translate to economic loss for the grower and therefore merit taking measures to control the disease. One objective of this study was to evaluate the resistance developed in populations of strawberry powdery mildew to chemical control measures. A fungicide assay was developed to evaluate the efficacy of six treatments (penthiopyrad, quinoxyfen, myclobutanil, trifloxystrobin, cyflufenamid, fluopyram + trifloxystrobin) for control of the disease. Nineteen isolates of strawberry powdery mildew were collected from Balico, Salinas, Watsonville, San Luis Obispo, Santa Maria, Ventura, and Oxnard CA and tested through the assay. The number of isolates resistant to each treatment was: penthiopyrad (7), quinoxyfen (6), myclobutanil (7), trifloxystrobin (2), cyflufenamid (1), fluopyram + trifloxystrobin (0). This documents resistance in P. aphanis to multiple chemicals used for its control. Documentation of any resistance is novel in California and novel worldwide with resistance to Fungicide Resistance Action Committee (FRAC) codes 7 and 13. Another objective of this study was to evaluate host plant resistance to strawberry powdery mildew. Twelve cultivars were evaluated in a winter greenhouse trial, sixteen cultivars in a summer greenhouse trial, and the ten cultivars shared in both trials were also evaluated in two fields. The cultivars found to be most susceptible to mildew infection were BG 3.324 and Royal Royce. The cultivars found to be the least susceptible to mildew infection were Fronteras, San Andreas, and Sweet Ann. The cultivars evaluated represent more than 55% of the state’s acreage and the host plant resistance information will be a valuable tool to growers looking to culturally control powdery mildew.
... The information provided in this study is a valuable contribution to the creation of a database on the fungal diversity, including pathogenic fungi in the country. According to our investigation the majority of determined host plants are herbs in contrast to Asia, where deciduous host plants dominate in number (Amano 1986, Takamatsu 2018. Especially, the genus Levellula is common and occurs mainly on herbaceous plants in the arid regions of Azerbaijan. ...
The present paper summarizes the taxonomic studies of Erysiphaceae (Helotiales, Ascomycota) in Azerbaijan. It represents a checklist of powdery mildews, which was prepared by combining all data collected from various works dealing with mycobiota of the country since mid of the last century. Consequently, 133 taxa belonging to the currently recognised genera – Arthrocladiella, Blumeria, Erysiphe, Golovinomyces, Leveillula, Neoërysiphe, Phyllactinia, Podosphaera, Sawadaea of the family Erysiphaceae have been reported. Host plants include angiosperms from 51 families and 227 genera. Current systematic position of each powdery mildew fungus was given with detailed information on their examined specimens.
... As one of the most important plant pathogenic groups, species of Erysiphaceae can infect ca. 10,000 species of angiosperms including many economically important, cultivated species such as cereals, vegetables, fruit trees, and other flowering plants ( Takamatsu 2018). ...
This is the twelfth contribution to the Fungal Diversity Notes series on fungal taxonomy, based on materials collected from many countries which were examined and described using the methods of morphology, anatomy, and strain culture, combined with DNA sequence analyses. 110 taxa are described and illustrated, including five new genera, 92 new species, eight new combinations and other taxonomic contributions (one new sequenced species, one new host and three new records) which are accommodated in 40 families and 1 incertae sedis in Dothideomycetes. The new genera are Amyloceraceomyces, Catenuliconidia, Hansenopezia, Ionopezia and Magnopulchromyces. The new species are Amyloceraceomyces angustisporus, Amylocorticium ellipsosporum, Arthrinium sorghi, Catenuliconidia uniseptata, Clavulina sphaeropedunculata, Colletotrichum parthenocissicola, Coniothyrium triseptatum, Cortinarius indorusseus, C. paurigarhwalensis, C. sinensis, C. subsanguineus, C. xiaojinensis, Diaporthe pimpinellae, Dictyosporella guizhouensis, Diplodia torilicola, Fuscoporia marquesiana, F. semiarida, Hansenopezia decora, Helicoarctatus thailandicus, Hirsutella hongheensis, Humidicutis brunneovinacea, Lentaria gossypina, L. variabilis, Lycoperdon lahorense, L. pseudocurtisii, Magnopulchromyces scorpiophorus, Moelleriella gracilispora, Neodevriesia manglicola, Neodidymelliopsis salvia, N. urticae, Neoroussoella magnoliae, Neottiella gigaspora, Ophiosphaerella chiangraiensis, Phaeotremella yunnanensis, Podosphaera yulii, Rigidoporus juniperinus, Rhodofomitopsis pseudofeei, Russula benghalensis, Scleroramularia vermispora, Scytinopogon minisporus, Sporormurispora paulsenii, Thaxteriellopsis obliqus, Tomentella asiae-orientalis, T. atrobadia, T. atrocastanea, T. aureomarginata, T. brevis, T. brunneoflava, T. brunneogrisea, T. capitatocystidiata, T. changbaiensis, T. citrinocystidiata, T. coffeae, T. conclusa, T. cystidiata, T. dimidiata, T. duplexa, T. efibulata, T. efibulis, T. farinosa, T. flavidobadia, T. fuscocrustosa, T. fuscofarinosa, T. fuscogranulosa, T. fuscopelliculosa, T. globospora, T. gloeocystidiata, T. griseocastanea, T. griseofusca, T. griseomarginata, T. inconspicua, T. incrustata, T. interrupta, T. liaoningensis, T. longiaculeifera, T. longiechinuli, T. megaspora, T. olivacea, T. olivaceobrunnea, T. pallidobrunnea, T. pallidomarginata, T. parvispora, T. pertenuis, T. qingyuanensis, T. segregata, T. separata, T. stipitata, T. storea, Trichoderma ceratophylletum, Tyromyces minutulus, Umbelopsis heterosporus and Xylolentia reniformis. The new combinations are Antrodiella descendena, Chloridium macrocladum, Hansenopezia retrocurvata, Rhodofomitopsis monomitica, Rh. oleracea, Fuscoporia licnoides, F. scruposa and Ionopezia gerardii. A new sequenced species (Graphis supracola), one new host (Aplosporella prunicola) and three new geographical records (Golovinomyces monardae, Paradictyoarthrinium diffractum and Prosthemium betulinum), are reported.
... Powdery mildews are obligate biotrophic ascomycetes that occur on a wide range of dicotyledonous and monocotyledonous host plants. The family Erysiphaceae has a nearly worldwide distribution, with the exception of the Antarctic region, and currently comprises around 900 species in 18 genera [1][2][3]. Golovinomyces was originally introduced by Braun [4] as a section of the genus Erysiphe (s. lat.) and was later raised to genus rank by Heluta [5]. ...
Background:
Previous phylogenetic analyses of species within the genus Golovinomyces (Ascomycota, Erysiphales), based on ITS and 28S rDNA sequence data, revealed a co-evolutionary relationship between powdery mildew species and hosts of certain tribes of the plant family Asteraceae. Golovinomyces growing on host plants belonging to the Heliantheae formed a single lineage, comprised of a morphologically differentiated complex of species, which included G. ambrosiae, G. circumfusus, and G. spadiceus. However, the lineage also encompassed sequences retrieved from Golovinomyces specimens on other Asteraceae tribes as well as other plant families, suggesting the involvement of a plurivorous species. A multilocus phylogenetic examination of this complex, using ITS, 28S, IGS (intergenic spacer), TUB2 (beta-tubulin), and CHS1 (chitin synthase I) sequence data was carried out to clarify the discrepancies between ITS and 28S rDNA sequence data and morphological differences. Furthermore, the circumscription of species and their host ranges were emended.
Results:
The phylogenetic and morphological analyses conducted in this study revealed three distinct species named, viz., (1) G. ambrosiae emend. (including G. spadiceus), a plurivorous species that occurs on a multitude of hosts including, Ambrosia spp., multiple species of the Heliantheae and plant species of other tribes of Asteraceae including the Asian species of Eupatorium; (2) G. latisporus comb. nov. (≡ Oidium latisporum), the closely related, but morphologically distinct species confined to hosts of the Heliantheae genera Helianthus, Zinnia, and most likely Rudbeckia; and (3) G. circumfusus confined to Eupatorium cannabinum in Europe.
Conclusions:
The present results provide strong evidence that the combination of multi-locus phylogeny and morphological analysis is an effective way to identify species in the genus Golovinomyces.
Powdery mildew poses a substantial threat to Chinese herbaceous peony (Paeonia lactiflora) cultivation, yet efficient identification methods for the pathogen are currently lacking, hampering early disease control. This study successfully identified Erysiphe paeoniae as the causative agent of powdery mildew in P. lactiflora in Beijing, leveraging morphological characteristics and rDNA ITS region sequencing. Furthermore, a high specificity and sensitivity specific PCR detection primers targeting E. paeoniae were developed based on ITS region sequences. Notably, these primers effectively circumvent contamination by host plant or other fungal DNA, enabling the detection of E. paeoniae DNA at concentrations as low as 1 × 10−15 ng/μL. This technological advancement provides a valuable tool for the early and rapid detection of E. paeoniae. Moreover, host range of E. paeoniae strain in our study was tested by inoculation combined with specific primers we developed. The isolated strain BJ20210618 can infect four species of Paeonia plants, including P. lactiflora, P. anomala, P. obovata, and P. veitchii. Among them, P. veitchii is a new host of E. paeoniae, reported for the first time in this study. Strikingly, this strain exhibited no infectivity towards Chinese tree peony (P. suffruticosa), diverging from prior reports suggesting E. paeoniae infects Chinese tree peony. We speculate that there may be different physiological races in E. paeoniae. We aligned the E. paeoniae strain BJ20210618 isolated from P. lactiflora in Beijing, China, E. paeoniae strain YN20220506 isolated from P. suffruticosa in Yunnan, China, along with the ITS sequences of 15 E. paeoniae strains and 13 closely related powdery mildews available on NCBI, and constructed a phylogenetic tree. Phylogenetic analysis of ITS sequences further supports these observations, distinguishing E. paeoniae from both P. lactiflora and P. suffruticosa into discrete clusters, highlighting the presence of distinct strains of E. paeoniae with different host specificities. This study not only enhances our understanding of the pathogen’s behavior and specificity but also provides invaluable tools and insights for effective disease management strategies.
The nucleotide sequences of the nuclear ribosomal DNA including 18S, 5.8S, and 28S rDNA and the internal transcribed spacer regions were determined for 33 powdery mildew taxa spanning 15 genera to infer the phylogenetic relationships for these fungi. Phylogenetic analyses revealed that Uncinula septata was placed in the primitive base to the large clade composed of all other powdery mildew taxa. Powdery mildews excluding Unc. septata were split into five major lineages. The Pseudoidium lineage consisted of six genera, i.e., Erysiphe, Microsphaera, Uncinula, Uncinuliella, Brasiliomyces, and Typhulochaeta, all of which are characterized by polyascal cleistothecia and Pseudoidium-type anamorph. The Eudoidium lineage consisted of three Erysiphe species (E. cichoracearum, E. orontii and E. galeopsidis) and Arthrocladiella mougeotii, which are characterized by polyascal cleistothecia and Euoidium-type anamorph. The endophytic lineage consisted of two Phyllactinia species (Phy. moricola and Phy. Kakicola), Leveillula taurica and Pleochaeta shiraiana, which are characterized by the presence of endophytic or partly endophytic mycelia. The fibrosin lineage consisted of the genera Sawadaea, Cystotheca, Podosphaera, and Sphaerotheca, all of which are characterized by the presence of well-developed fibrosin bodies in the conidia and conidiophores. The monocot lineage consisted of a single species, Blumeria graminis, which is well characterized by being parasitic to monocots, especially to cereal plants. Character polarization was discussed on several major characteristics. The mycelioid appendage which has long been regarded as an ancestral character may be a derived character as a result of an event that may have occurred multiple times independently due to convergence. Euoidium-type anamorph and clavate appressorial germ tube are considered to be ancestral characters to Pseudoidium-type anamorph and lobed germ tube. Ectophytic nature and polyascal cleistothecia are also regarded as ancestral features to endophytic nature and monoascal cleistothecia.
Erysiphe gracilis is a powdery mildew species that occurs on evergreen oak species belonging to Quercus subgen. Cyclobalanopsis in East Asia (China and Japan). In a previous report, we found that E. gracilis var. gracilis is divided into four genotypes each of them forming a separate clade with strong bootstrap support. In this study, we further investigated genotype speciation in E. gracilis var. longissima occurring on Q. acuta and Q. sessilifolia, and found that this variety is also divided into two distinct genotypes. These results suggested that E. gracilis represents a species complex consisting of six different species. Based on detailed morphological examinations correlating with results of molecular sequence analyses, we propose to divide E. gracilis into six species, encompassing three new species (E. uncinuloides, E. pseudogracilis, and E. longiappendiculata), one new name (E. longifilamentosa), and two known species (E. gracilis s. str. and E. hiratae). A key to the species concerned is provided.
Cystotheca lanestris on the new host Quercus canbyi, Microidium bauhiniicola on the new host Bauhinia macranthera and an undescribed species of Phyllactinia on Mimosa aculeaticarpa have recently been collected in Mexico. Analyses of morphological traits and molecular sequence data led to identifications of the causal agents of the powdery mildew diseases involved. Microidium bauhiniicola, hitherto only known from Argentina and Brazil, is new to Mexico. The phylogenetic analysis revealed an isolated position distant from Microidium indicating an undescribed genus, which is introduced as Bulbomicroidium gen. nov. Sequences derived from a Mexican specimen of C. lanestris on Quercus canbyi agree completely with other North American sequences, but differ from sequences retrieved from Asian collections, suggesting that C. lanestris in Asia is not conspecific with C. lanestris s. str. in North America. A new species of Phyllactinia on Mimosa malacophylla is morphologically similar to P. dalbergiae but readily distinguishable by differences in the asexual morph. Based on morphological peculiarities and results of molecular sequence analyses, this species is described as Phyllactinia mimosae sp. nov.
A new powdery mildew species of the genus Microidium (Erysiphaceae) found on Phyllanthus reticulatus (Phyllanthaceae) in Thailand is described. Microidium phyllanthireticulati [= Oidium phyllanthi var. reticulati] is characterized by having amphigenous colonies on the host surface, long conidiophore foot-cells twisted at the base, and barrelshaped to cylindrical conidia with Microidium-type germ tubes. The new species differs from the allied and morphologically very similar M. phyllanthi in producing smaller conidia and conidiophores with longer foot-cells. Analyses of rDNA ITS + 28S sequence data support the separation of M. phyllanthi-reticulati from M. phyllanthi. The new species is described and illustrated in detail, and compared with other species assigned to Microidium.
Parauncinula, a genus belonging to the Erysiphaceae (powdery mildew family), consisted of only two species, P. curvispora and P. septata, which are distributed only in China and Japan (endemic to East Asia). This genus split from other powdery mildew genera at an early stage of evolution, and thus has been considered as one of the most ancestral genera in the Erysiphales. Phylogenetic analyses using rDNA internal transcribed spacer (ITS) region and 28S rRNA gene sequences indicated that one of the species, P. septata, is divided into three distinct genotypes. The ITS sequence similarities between the three genotypes were 96% or less, suggesting species level differences among the genotypes. Combined with detailed morphological observations, P. septata s. lat. is divided into three species, viz. P. septata s. str., P. polyspora, and P. uncinata. These species are clearly defined by morphological characteristics such as the number of ascospores per ascus and morphology of appendages, as well as DNA sequences. A key to the species of Parauncinula is also presented.
Powdery mildew fungi as parasites of vascular plants are supposed to appear not earlier than in the second half of the Cretaceous period (98 MY ago) and not later than in the Middle Palaeocene (60 MY ago) in the territory of old Angarida which corresponds to the South-Eastern part of present China. Basing on the data on paleogeography and paleobotany with regard for Koppen-Wegener hypothesis on the drift of the Earth poles it is proved that beginning from the end of the Cretaceous period to the middle of Palaeocene the given part of Angarida, Chukotka, Alaska and Pacific Ocean coast of North America were arranged at the same geographical latitude in the subtropical zone and were not separated by a water barrier. Thus, 65-60 MY ago there existed a corridor favourable for migration of heat-loving representatives of order Erysiphales. Powdery mildews could get to Europe via three corridors: northwards of the Urals ridge (the end of Oligocene; only cold-resistant species); southwards of this ridge (the end of Miocene; species confined to the heat-moderate zone) and downwards of the Akchygil transgression (Late Pliocene; xerophylic representatives of order Erysiphales). Further distribution of powdery mildews is connected with the development of humanity and population migrations.
Based on 18S, 5.8S, and 28S rDNA sequences, the phylogenetic position of Uncinula septata within the Erysiphales has been inferred. Although appendages of the ascomata are uncinula like, i.e., unbranched with curved-coiled apices, U. septata is situated at the very base of the large Erysiphales cluster, far away from the “pseudoidium clade” (Erysiphe emend., including Microsphaera and Uncinula). Morphologically, U. septata differs from the species of Erysiphe sect. Uncinula ( ≡ Uncinula) in having terminal, pluriseptate ascoma appendages, curved ascospores, and the absense of an anamorph. This species is a basal, tree-inhabiting powdery mildew with some additional ancestral characteristics, viz., uncinula-like appendages and 8-spored asci. The new genus Parauncinula with U. septata as the type species is proposed. Uncinula curvispora ( ≡ U.septata var. curvispora) is tentatively maintained as a separate species, which is also assigned to Parauncinula.
A phylogenetic analysis of the Erysiphe with uncinuloid ascoma appendages (Erysiphe section Uncinula, Erysiphales, Ascomycota) on Carpinus spp. was done using sequences of the rDNA ITS regions and the D1/D2 domains of the 28S rDNA. These results, combined with morphological data, revealed a complex consisting of several distinct taxa. These included the already described Erysiphe
carpinicola on C. japonica distinguishable from the Erysiphe sp. on C. betulus and C. tschonoskii as well as the one on C. laxiflora. Thus, it was shown that Oidium
carpini, described from Europe on Carpinus betulus, the powdery mildew with uncinula-like ascomata, recently found in Europe on this host, as well as an Erysiphe on C. tschonoskii in Japan, described previously as E. carpinicola, all belong to a single new species, named E. arcuata in this paper. As the powdery mildew on C. laxiflora was also distinct from other known species, it is named E. carpini-laxiflorae in this paper. The already described E. pseudocarpinicola and Erysiphe sp. on Carpinus cordata are two additional taxa, which are morphologically and genetically distinguished from the other species of Erysiphe sect. Uncinula on Carpinus spp.
The very close relationship between the genera Erysiphe s.str. ( + Erysiphe sect. Erysiphe), Microsphaera, and Uncinula, which are connected by numerous intermediate taxa, is strongly supported by light as well as scanning electron microscopical features and has recently been confirmed by examinations of nucleotide sequences of rDNA internal transcribed spaces (ITS). Erysiphe s.str. and Microsphaera did not group into separate monophyletic lineage, but formed several small mixed clusters. It turned out that the formation of branched ascoma appendages does not have any taxonomic value at generic level. Therefore, Microsphaera is reduced to synonymy with Erysiphe s.str., and the new combinations, which are necessary, are introduced. Uncinula spp. form a basal subclade of the Erysiphe s.str./Microsphaera (Pseudoidium) clade, but since some species of Erysiphe s.str. belong in this subclade, it is necessary to reduce Uncinula to synonymy with the latter genus, too. Furthermore, examinations of nucleotide sequences of rDNA ITS regions of numerous taxa belonging to tribe Cystotheceae showed that Podosphaera and Sphaerotheca did not form separate monophyletic clades. Taxa of Sphaerotheca sect. Sphaerotheca and sect. Magnicellulatae grouped together with two different sets of Podosphaera spp. in two separate subclades of a single Podosphaera/Sphaerotheca clade. Based on these results and since Podosphaera and Sphaerotheca are morphologically only distinguished by having appendages which are branched and simple, respectively, it is proposed to merge the two genera. New combinations for Sphaerotheca spp. under Podosphaera are introduced.
Molecular phylogeny suggests a close relationship of Asteraceae to the early evolution of Golovinomyces. The family Asteraceae, with a geographic origin in South America, expanded into the Northern Hemisphere, where it may have been infected by an ancestor of Golovinomyces, thus starting a close host–parasite relationship. Using this event as a calibration point, we designed molecular clocks for powdery mildews using the 28S rDNA D1/D2 and internal transcribed spacer (ITS) regions. According to these clocks, the powdery mildews originated in the Late Cretaceous and the first radiation of the major lineages occurred at the Cretaceous/Paleogene boundary. Ancestral powdery mildews may have first radiated on broad-leaved deciduous trees in the high latitudes of the Northern Hemisphere, and continued further speciation whilst migrating to southward during the world cooling in the Paleogene and Neogene periods. The cradle of four herb infecting genera, viz. Blumeria, Golovinomyces, Leveillula, and Neoërysiphe may be within the area extending from Central/West Asia to the Mediterranean.
Powdery mildew fungi (Erysiphales, Ascomycota) are obligate biotrophs that infect a wide range of angiosperms. Phylogenetic analyses based on the nucleotide sequences of the nuclear ribosomal DNA revealed that the powdery mildew fungi are divided into five major lineages. The respective lineage was well defined by the morphology of conidial stage, but not of ascomata. In this fungal group, tree-parasitic taxa are generally ancestral, and multiple events of host expansion from trees to herbs have occurred within the respective lineage. Accompanying the host expansion to herbs, simplification of appendage morphology has occurred multiple times. The simple, mycelioid appendages are thus a result of convergence. The host expansion route was investigated in detail in the tribe Cystotheceae. Two sections of the genus Sphaerotheca were derived from the genus Podosphaera separately. The section Magnicellulatae was derived from a Podosphaera species parasitic to Prunus (Rosaceae), acquired parasitism to the Scrophulariaceae, and then expanded host range into the Asteraceae. After genetic radiation on the Asteraceae, they further expanded their host ranges into other plant families. According to the molecular clock (1.26%/100 million years, myr) reported by Berbee and Taylor, splitting of the Erysiphales and the Myxotrichaceae and first divergence within the Erysiphales was calculated to have occurred 100 and 76myr ago, respectively.
The genusMicrosphaera has been considered to be derived from sectionErysiphe of the genusErysiphe by a single event. Cleistothecial appendages are the most distinct difference between the two genera and have an important
role for overwintering. To understand the phylogenetic relationship betweenErysiphe sectionErysiphe andMicrosphaera more precisely, phylogenetic trees were constructed using the nucleotide sequences of the rDNA ITS region from 11Erysiphe (sectionErysiphe) and 16Microsphaera taxa. The phylogenetic trees indicated the close relationship between the two genera. However, the generaErysiphe (sectionErysiphe) andMicrosphaera did not group into separate monophyletic lineages; instead, they formed several small clusters that were mixed together.
This result suggests that the differentiations of the genera occurred two or more times independently. This also supports
the idea that appendage morphology does not always accurately reflect the phylogeny of the powdery mildews because the morphology
of appendages may evolve convergently under the selection pressure of their particular biotopes (host plants).
Powdery mildew fungi found on leaves, shoots, and stems of Phyllanthus acidus, P. amarus, and P. reticulatus proved to be a fungus having morphology unique in the Erysiphaceae. Light micrographs of a new germination pattern are added to discuss differences to other four germination patterns of the powdery mildews. The rDNA sequences (28S and 18S regions) of the fungi found on Phyllanthus spp. form a distinct monophyletic clade strongly supported by bootstrap (100%) in 18S + 28S trees, which indicates that the fungus is an isolated fungal group among the Erysiphaceae in tribal level. Because we cannot find the teleomorphic state of this fungus, a new subgenus Microidium of anamorphic genus Oidium is proposed to accommodate this organism.
Based on a comparative phylogenetic analysis of Goloviomyces and their host tribes of the Asteraceae, we speculate that Golovinomyces first acquired parasitism to the Asteraceae after migration of the family into the Northern Hemisphere and before the divergence of the tribe Carduaeae. The divergence time of the Carduaeae is estimated to be 25.2Myr ago based on the molecular clock of rbcL sequences of the Asteraceae. When 25.2Myr is given at the node of the first split of the phylogenetic tree of Golovinomyces, nucleotide substitution rates of the Erysiphales are calculated to be 2.52 × 10-9 per site per year (0.01D=3.97Myr) in the ITS region and 6.5 × 10-10 per site per year (0.01D=15.4Myr) in the D1 and D2 regions of the 28S rDNA.
Phylogenetic relationships of Erysiphals within Ascomycota were inferred from the newly determined sequences of the 18SrDNA and partial sequences of the 28SrDNA including the D1 and D2 regions of 1O Erysiphales taxa．Phylogenetic analyses revealed that the Erysiphales form a distinct clade among ascomycetous fungi, Suggesting that the Erysiphales diverged from a single ancestral taxon. The Myxotrichaceae of the Onygenales was distantly related to the other onygenalean families and was the sister group to the Erysiphales clade, with which it combined to form a clade．The Erysiphales / Myxotrichaceae clade was also closely related to some discomycetous fungi (Leotiales, Cyttariales and Thelebolaceae) including taxa that form cleistothecial ascomata. The present molecular analyses as well as previously reported morphological ofservations ssuggest the possible exsistence of a novel evolutionary pathway from cleistothecial discomycetous fungi to Erysiphales and Myxotrichaceae. However, since most of these fungl, except for the Erysiphales，are saprophytic on dung and/or plant materials．the questions of how and why an obligate biotroph like the Erysiphales radiated from the saprophytjc fungi remain to be addressed. We also estimated the radiation time of the Erysiphales using the 18SrDNA sequences and the two molecular clocks that have been previously reported. The calculation showed that the Erysiphales split from the Myxotrichaceae 190-127 myr ago. Since the radiation time of the Erysiphales does not exceed 230 myr ago, even when allowance is made for the uncertainty of the molecular clocks, it is possible to consider that the Erysiphales evolved after the radiation of angiosperms. The results of our calculation also showed that the first radiation within the Erysiphales(138-92 myr ago）coincided with the date of a major diversification of angiosperms(130-90 myr ago). These results may support our early assumption that the radiation of the Erysiphales coincided with the evolution of angiosperm plants.
The nucleotide sequences of the nuclear ribosomal DNA including 18S, 5.8S, and 28S rDNA and the internal transcribed spacer regions were determined for 33 powdery mildew taxa spanning 15 genera to infer the phylogenetic relationships for these fungi. Phylogenetic analyses revealed that Uncinula septata was placed in the primitive base to the large clade composed of all other powdery mildew taxa. Powdery mildews excluding Unc. septata were split into five major lineages. The Pseudoidium lineage consisted of six genera, i.e., Erysiphe, Microsphaera, Uncinula, Uncinuliella, Brasiliomyces, and Typhulochaeta, all of which are characterized by polyascal cleistothecia and Pseudoidium-type anamorph. The Eudoidium lineage consisted of three Erysiphe species (E. cichoracearum, E. orontii and E. galeopsidis) and Arthrocladiella mougeotii, which are characterized by polyascal cleistothecia and Euoidium-type anamorph. The endophytic lineage consisted of two Phyllactinia species (Phy. moricola and Phy. kakicola), Leveillula taurica and Pleochaeta shiraiana, which are characterized by the presence of endophytic or partly endophytic mycelia. The fibrosin lineage consisted of the genera Sawadaea, Cystotheca, Podosphaera, and Sphaerotheca, all of which are characterized by the presence of well-developed fibrosin bodies in the conidia and conidiophores. The monocot lineage consisted of a single species, Blumeria graminis, which is well characterized by being parasitic to monocots, especially to cereal plants. Character polarization was discussed on several major characteristics. The mycelioid appendage which has long been regarded as an ancestral character may be a derived character as a result of an event that may have occurred multiple times independently due to convergence. Euoidium-type anamorph and clavate appressorial germ tube are considered to be ancestral characters to Pseudoidium-type anamorph and lobed germ tube. Ectophytic nature and polyascal cleistothecia are also regarded as ancestral features to endophytic nature and monoascal cleistothecia.
Three powdery mildew species present on Nothofagus (viz. Erysiphe magellanica, E. nothofagi and E. patagoniaca) are endemic to South America and have unique ascomatal appendages that are not found in powdery mildews of the northern hemisphere. We determined the nucleotide sequences of the rDNA internal transcribed spacer regions and D1/D2 domains of the 28S rDNA of these three powdery mildew species to reveal their phylogenetic relationships with powdery mildews of the northern hemisphere. Although the molecular phylogenetic analyses indicated that the three Nothofagus powdery mildews are closely related to each other they did not group into one clade in either the ITS or 28S trees. Kishino-Hasegawa, Shimodaira-Hasegawa and Templeton tests could not significantly reject the constrained trees that were constructed based on the assumption that the Nothofagus powdery mildews would form a single clade. Based on this result and the evidence that all Nothofagus powdery mildews are endemic to South America and have similar morphological characteristics, it is likely that these three species diverged from a single ancestor present on Nothofagus. Calibration of evolutionary events with molecular clocks suggested that the Nothofagus powdery mildews split from the northern hemisphere relatives 22-16 million y ago (Ma) in the middle Miocene, and divergence among the Nothofagus powdery mildews occurred 17-13 Ma. These results do not support a southern hemisphere base of the Nothofagus powdery mildews.
A fungus isolated from Norway maple (Acer platanoides) in the Boston, Massachusetts, area was determined to be a species of Glomerella, the teleomorph of Colletotrin chum 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.
Golovinomyces is a strictly herb-parasitic genus in the Erysiphaceae. Host-parasite co-speciation was reported recently between the genus Golovinomyces and Asteraceae from molecular phylogenetic analyses. The Asteraceae originated in South America and latterly expanded their geographic distribution into the Northern Hemisphere. If the co-speciation between Golovinomyces and Asteraceae originated in South America, the geographic origin of Golovinomyces could be assumed to be South America. To address this question, Golovinomyces species from hosts of the tribe Mutisieae, an asteraceous tribe endemic to South America, were collected and the ITS and 28S rDNA regions sequenced. Results indicate that Oidium mutisiae and Golovinomyces leuceriae isolated from the Mutisieae do not belong at the base of the Golovinomyces tree. Instead, they are situated separately within two different clades of Golovinomyces isolates from the Northern Hemisphere. Therefore, the tribe Mutisieae is not the most early host of Golovinomyces. Present results suggest that Golovinomyces originated in the Northern Hemisphere, and not in South America. The new species Oidium reginae for the previous O. mutisiae on Mutisia decurrens is proposed.
A phylogeny of Erysiphe sect. Uncinula on Carpinus spp. was reconstructed using the 28S rDNA sequences and a combined alignment of the 28S, ITS, and IGS rDNA sequences. The analysis was supplemented with morphological data obtained from examination of voucher specimens. A sequence of Erysiphe sect. Uncinula on C. cordata formed a distinct lineage separated from sequences of other Erysiphe species on Carpinus spp., indicating a cryptic species, which is described as E. paracarpinicola. The new species is genetically as well as morphologically most similar to E. carpinicola s. str., but differs in having fewer asci per chasmothecium (mainly 3–5 vs 4–10) and shorter chasmothecial appendages. A key to species of Erysiphe sect. Uncinula on Carpinus spp. is provided.
Fungal phylogenetics has always been based on characters, but technological and intellectual advances are introducing new kinds of characters and new ways of thinking about them. First light microscopy, then electron microscopy, and now DNA sequencing successively upset previous views of fungal relationships. Phenetics, cladistics, and computerized data analysis and phylogenetic tree generation are now changing the intellectual rules for taxonomy and phylogenetics. The combination of new characters and new analytical tools have supported some taxonomic groups, established some new ones, and demolished a few old ones.
A new assemblage of Late Cretaceous fossil plants (the Kamikitaba assemblage) was discovered from the Ashizawa Formation of Futaba Group (Early Coniacian; 89Ma). The flora includes well-preserved mesofossils of angiosperm flowers, fruits, seeds, leaf fragments and woods.Some aspects on the origin of angiosperms and the vegetational consequences of Cretaceous and Paleogene flora are reviewed in the paper.
To understand the evolutionary history of Erysiphaceae tribe Cystotheceae, phylogentic trees were constructed from the nucleotide sequences of the ribosomal DNA internal transcribed spacer of 28 taxa of the fungal ingroup and two outgroup taxa. The first split of the ingroup taxa occurred between a clade composed of the genus Cystotheca and a clade composed of the genera Podosphaera and Sphaerotheca. Podosphaera and Sphaerotheca did not separate into clades. Instead, Podosphaera species parasitic to Prunus and Sphaerotheca section Magnicellulatae grouped together, with the remaining Podosphaera species and Sphaerotheca section Sphaerotheca forming another subclade. Since the first splits were shared by Podosphaera species in both subclades, it was assumed the ancestral features of both subclades were Podosphaera-like and the genus Sphaerotheca derived from a Podosphaera-like ancestral taxon on at least two independent occasions. The results of this study suggest that ancestral fungi of the tribe Cystotheceae were originally arborparasitic, and transition from arbor-parasitism to herb-parasitism may have occurred at least twice independently, accompanied by a morphological change of appendages. The mycelioid appendage of the genus Sphaerotheca and other herb-parasitic genera seems to have evolved convergently at multiple times as an adaptation to herb-parasitism.
Immunofluorescence microscopy with two monoclonal antibodies raised to two Trichoderma reesei cellobiohydrolases revealed antigen localization at the germ tube tips of Erysiphe graminis f.sp. hordei. Cellobiohydrolase II was present principally at the appressorial germ tube tip and cellobiohydrolase I at the primary germ tube tip. Cell turgor measurements, determined by cytorrhysis and plasmolysis experiments revealed that mature E. graminis appressoria produced a maximum turgor pressure of approximately 2–4 MPa, coincident with host cell penetration from the appressorium. Taken collectively, these results imply that host penetration by E. graminis is effected by a combination of enzyme activity and mechanical force.
The phylogenetic position of Uncinula forestalis within the Erysiphales has been inferred from 5.8S, 18S, and 28S rDNA sequences. Although the appendages of the ascomata are Uncinula-like, i.e. unbranched with curved-coiled apices, U. forestalis is situated at the very base of the large Erysiphales cluster, far from the 'Pseudoidium' clade (Erysiphe, including Microsphaera and Uncinula) and separate from the recently introduced basal genus Parauncinula. U. forestalis differs morphologically from the species of Erysiphe sect. Uncinula in having terminal, fasciculate (as in Podosphaera tridactyla), septate ascoma appendages and a Euoidium-like anamorph (conidia catenate). In Parauncinula, the appendages are also terminal but not fasciculate, the ascospores are curved, and the anamorph is lacking. Uncinula forestalis is a basal, tree-inhabiting powdery mildew with some additional ancestral characteristics, including Uncinula-like appendages and 6-8-spored asci. The new genus Caespitotheca gen. nov. is described with C. forestalis comb. nov. (syn. Uncinula forestalis) as the type species. We calculated the timing of the divergence of U. forestalis and P. septata using a molecular clock of the Erysiphales (6.5 x 10-10 changes per site per year in domains D1 and D2 of 28S rDNA) and a 28S rDNA data set. The results suggest that the divergence of U. forestalis and P. septata from other Ervsiphales occurred between 90 and 80 Myr ago; i.e. the divergence of the two ancestral species may have occurred in the late Cretaceous.
The powdery mildew monotypic genus Queirozia was reduced to a synonym of Pleochaeta in 1982. Now, a re-examination of the type material of Queirozia and of two other specimens showed that Queirozia turbinata has a very distinct combination of characters that do not allow its placement within Pleochaeta. It has forked special aerial hyphae, subclavate and predominantly lemon-shaped conidia, and both conidiophores and conidia varying from greyish to yellowish brown (a feature that appears to be unique for this fungus within the Erysiphales). This may represent the first dematiaceous anamorphic powdery mildew known to science. This fungus also has hemiendophytic mycelium, a character considered almost exclusive to the tribe Phyllactinieae. The outer wall surface pattern of wrinkled and turgid conidia of Q. turbinata as observed under the SEM is different from those presented in the literature for this tribe. Molecular analysis showed that Q. turbinata belongs to the tribe Phyllactinieae and is phylogenetic closer to Pleochaeta than to Leveillula or Phyllactinia. It is therefore acknowledged that Queirozia is closely related to Pleocheta but too distinct morphologically from this genus to be accepted as a synonym. Emended descriptions of Queirozia and Q. turbinata are presented.
Phylogenetic analyses of Erysiphe alphitoides s. lat. using sequences of the rDNA ITS region and the D1/D2 domains of the 28S rDNA revealed a complex consisting of several genetically and morphologically distinguished taxa, including the already described Erysiphe alphitoides s. str. and E. hypophylla. The ascomata (chasmothecia) of E. hypophylla are morphologically very similar to those of E. alphitoides, but the two species are easily distinguishable by their symptoms, as well as the shape and size of the conidia. The fungus on Quercus phillyraeoides, distributed in warmer regions in southern Japan, is genetically clearly separated from E. alphitoides s. str., and morphologically characterized by having chasmothecia with appendages consistently shorter than the chasmothecial diameter. This fungus, named Erysiphe quercicola in this paper, is also able to infect some other oak species, and it is genetically identical with anamorphs on some tropical trees of other host genera. Collections of E. alphitoides s. lat. on Quercus acutissima and Q. variabilis, both belonging to Quercus sect. Cerris, are genetically distinct from E. alphitoides s. str., E. hypophylla and E. quercicola. They form two genetically and morphologically differentiated groups. The hypophyllous taxon on Q. acutissima and Q. variabilis, named Erysiphe hypogena in this paper, is characterized by forming distinctive persistent hypophyllous mycelial patches, causing necrotic discolouration of the host tissue. The epiphyllous taxon on these hosts, for which the name E. epigena is proposed, differs in having epiphyllous mycelium, smaller chasmothecia with fewer appendages, and does not cause leaf discolouration.
A new subgenus, Microidium, of Oidium (Erysiphaceae) on Phyllanthus spp
- C To-Anun
- S Kom-Un
- S Limkaisang
- W Fangfuk
- Y Sato
- S Takamatsu
．被子植物の起源と初期進化．北海道大学出 版会，札幌．
- 高橋正道
高橋正道(2006) ．被子植物の起源と初期進化．北海道大学出
版会，札幌．