Erysiphe Species Research Articles

Hidden invasion and niche contraction revealed by herbaria specimens in the fungal complex causing oak powdery mildew in Europe

Deciphering the dynamics involved in past microbial invasions has proven difficult due to the inconspicuous nature of microbes and their still poorly known diversity and biogeography. Here we focus on powdery mildew, a common disease of oaks which emerged in Europe at the beginning of the twentieth century and for which three closely related Erysiphe species are mainly involved. The study of herbaria samples combined with an experimental approach of interactions between Erysiphe species led us to revisit the history of this multiple invasion. Contrary to what was previously thought, herbaria sample analyses very strongly suggested that the currently dominant species, E. alphitoides, was not the species which caused the first outbreaks and was described as a new species at that time. Instead, E. quercicola was shown to be present since the early dates of disease reports and to be widespread all over Europe in the beginning of the twentieth century. E. alphitoides spread and became progressively dominant during the second half of the twentieth century while E. quercicola was constrained to the southern part of its initial range, corresponding to its current distribution. A competition experiment provided a potential explanation of this over-invasion by demonstrating that E. alphitoides had a slight advantage over E. quercicola by its ability to infect leaves during a longer period during shoot development. Our study is exemplary of invasions with complexes of functionally similar species, emphasizing that subtle differences in the biology of the species, rather than strong competitive effects may explain patterns of over-invasion and niche contraction.

Taxonomy and phylogeny of the Erysiphe lonicerae complex (Helotiales, Erysiphaceae) on Lonicera spp.

The phylogeny and taxonomy of powdery mildews, belonging to the genus Erysiphe, on Lonicera species throughout the world are examined and discussed. Phylogenetic analyses revealed that sequences retrieved from Erysiphe lonicerae, a widespread powdery mildew species distributed in the Northern Hemisphere on a wide range of Lonicera spp., constitutes a complex of two separate species, viz., E. lonicerae (s. str.) and Erysiphe ehrenbergii comb. nov. Erysiphe lonicerae occurs on Lonicera spp. belonging to Lonicera subgen. Lonicera (= subgen. Caprifolium and subgen. Periclymenum), as well as L. japonica. Erysiphe ehrenbergii comb. nov. occurs on Lonicera spp. of Lonicera subgen. Chamaecerasus. Phylogenetic and morphological analyses have also revealed that Microsphaera caprifoliacearum (≡ Erysiphe caprifoliacearum) should be reduced to synonymy with E. lonicerae (s. str.). Additionally, Erysiphe lonicerina sp. nov. on Lonicera japonica in Japan is described and the new name Erysiphe flexibilis, based on Microsphaera lonicerae var. flexuosa, is introduced. The phylogeny of Erysiphe ehrenbergii and E. lonicerae as well as other Erysiphe species on honeysuckle is discussed, and a survey of all species, including a key to the species concerned, is provided. Citation: Bradshaw M, Braun U, Götz M, Takamatsu S (2020). Taxonomy and phylogeny of the Erysiphe lonicerae complex (Helotiales, Erysiphaceae) on Lonicera spp. Fungal Systematics and Evolution 7: 49-65. doi: 10.3114/fuse.2021.07.03.

<p><strong>A new species of the elm powdery mildew species complex (Erysiphaceae) on Chinese elm (<em>Ulmus parvifolia</em>) in East Asia segregated from <em>Erysiphe ulmi</em></strong></p>

Powdery mildews are common pathogens on wild elm trees as well as on planted ornamentals in Asia and Europe. The taxonomy of the powdery Erysiphe species on elms (Ulmus spp., Ulmaceae) is complicated by taxonomical changes and inconsistently labelled DNA data in databases and publications. Based on morphology and phylogenetic analysis of new collections from Germany and Taiwan, E. ulmi from Europe is revised, while specimens on U. parvifolia from East Asia revealed a separate clade indicating an undescribed species. Morphologically, both species can be distinguished by length of the foot cell of the conidiophore, whereas the teleomorph characteristics were not significantly distinctive.

An easy and robust method for isolation and validation of single-nucleotide polymorphic markers from a first Erysiphe alphitoides draft genome

Isolating genetic markers is often costly and time-consuming for non-model fungal species. However, these markers are of primary importance to identify the origin of invasive species and to infer their reproductive mode and dispersal ability. We slightly modified a recent molecular method to quickly isolate and validate single-nucleotide polymorphism (SNP) markers, from a first Erysiphe alphitoides draft genome, one of the main causal agent of oak powdery mildew in Europe. Although the draft assembly was strongly fragmented (555,289 contigs), we successfully isolated 1700 SNPs from 75 single-copy genes conserved in most fungal genomes. Ninety percent of them allowed to clearly distinguish the two main Erysiphe species reported on European oaks: E. alphitoides and E. quercicola. Thirty-six SNPs, located in distinct genes, were then validated using a strategy of MassArray genotyping on 95 E. alphitoides isolates sampled in Europe. This genotyping showed that only monospore isolates had the expected haploid signature, whereas direct genotyping from field leaves showed signature of mixed infection. Considering haploid isolates, these markers led to the first results of population genetic diversity, and suggested that E. quercicola may have a more asexual reproduction than its sister species, E. alphitoides.

Phylogeny and taxonomy of powdery mildew on Viburnum species

ABSTRACT The phylogeny and taxonomy of powdery mildew on Viburnum species is evaluated and discussed. Morphological and phylogenetic analyses revealed two new species and demonstrated that Erysiphe hedwigii and E. viburni should be reduced to synonymy and are referred to herein as E. viburni. The two new species, E. viburniphila and E. pseudoviburni, previously hidden under E. viburni (including E. hedwigii), is described on the basis of European, North American, and East Asian powdery mildew collections on Viburnum edule, V. tinus, V. odoratissimum var. awabuki, and V. sieboldii. The sexual morph of E. viburniphila is similar to that of E. viburni; however, morphological differences exist in their asexual morphs. Analyses of sequences from the internal transcribed spacer (ITS) and 28S genomic regions of Erysiphe species obtained on Viburnum species (and other closely allied Eryisphe species) throughout the world reveled that E. viburniphila and E. pseudoviburni are in two different monophyletic groups that are separate from all other Erysiphe species. Erysiphe hedwigii and E. viburni on Viburnum species have often been recognized as separate species based on morphological differences in the size of their chasmothecia and the number of chasmothecial appendages. Taxonomic conclusions based on these morphological distinctions within these species are unreliable (these characters are rather variable and often have overlapping ranges). The present phylogenetic analyses suggest that E. hedwigii has to be reduced to synonymy with E. viburni. To fix the application of the species names E. hedwigii and E. viburni, epitypes have been designated for these taxa with ex-epitype sequences. Additionally, the Asian species E. miranda is phylogenetically confirmed as a species of its own, described in detail and discussed.

Erysiphedeutziicola sp. nov. (Erysiphaceae, Ascomycota), a powdery mildew species found on Deutziaparviflora (Hydrangeaceae) with unusual appendages.

A powdery mildew (Erysiphales) has recently been collected on leaves of an ornamental shrub Deutziaparviflora in Baihua Mountain, Beijing, China. Microscopic examination of the chasmothecia suggested a species belonging to Erysiphesect.Erysiphe, above all due to mycelioid chasmothecial appendages, although circinate apices of the appendages were rather in favour of Erysiphesect.Uncinula, which is a fairly rare combination of appendage characteristics in Erysiphe. Phylogenetic analyses of ITS and 28S rDNA sequences demonstrated that the two examined powdery mildew collections on D.parviflora clustered together as an independent lineage within Erysiphe with 100% bootstrap support, representing a species of its own, which is phylogenetically allied to, but clearly distinct from Erysiphedeutziae and, in addition, morphologically quite different from all known Erysiphe species on hosts belonging to the Hydrangeaceae. The new species on D.parviflora is described as Erysiphedeutziicola.

From leaf to continent: The multi-scale distribution of an invasive cryptic pathogen complex on oak

Abstract The spatial distribution and niche differentiation of three closely related species (Erysiphe alphitoides, Erysiphe quercicola and Erysiphe hypophylla) causing oak powdery mildew was studied at scales ranging from the European continent, where they are invasive, to a single leaf. While E. alphitoides was dominant at all scales, E. quercicola and E. hypophylla had restricted geographic, stand and leaf distributions. The large-scale distributions were likely explained by climatic factors and species environmental tolerances, with E. quercicola being more frequent in warmer climates and E. hypophylla in colder climates. The extensive sampling and molecular analyses revealed the cryptic invasion of E. quercicola in nine countries from which it had not previously been recorded. The presence of the three species was also strongly affected by host factors, such as oak species and developmental stage. Segregation patterns between Erysiphe species were observed at the leaf scale, between and within leaf surfaces, suggesting competitive effects.

First Conclusive Report of an Erysiphe sp. Causing Powdery Mildew on Moth Vine (Araujia sericifera) in Australia and Worldwide

Moth vine (Araujia sericifera, Apocynaceae), native to South America, has been introduced as an ornamental plant to many parts of the world and has become an invasive environmental weed in some countries such as Australia and New Zealand. In May 2017, heavy powdery mildew infection was observed on moth vine in Ravensbourne National Park, Queensland, and also at two sites in Sydney, NSW, Australia. Powdery mildew mycelium covered large parts of the upper surfaces of older leaves with other parts of the plants not exhibiting disease symptoms. Conidiophores consisted of foot-cells, somewhat curved to sinuous at the base, (19-) 21 to 33 × 7 to 10 µm, followed by one or two cells of approximately the same length, each 14 to 25 (-29) × 7 to 10 µm, and conidia produced singly. Conidia were subcylindrical or ellipsoid-ovoid, (27-) 29 to 41 × 16 to 21 μm, and produced germ tubes apically or subapically, with lobed ends. Hyphal appressoria were lobed to multilobed. The sexual morph was not found. Based on these characteristics, the powdery mildew fungus was identified as an Erysiphe sp. (Braun and Cook 2012). Specimens from the three collection sites were deposited in the Queensland Plant Pathology Herbarium as BRIP 66127-66129. The rDNA ITS region was sequenced for each specimen as described by Kiss et al. (2018). The 552-bp long ITS sequences (deposited in GenBank as MG551719–21) were identical to several others including LC009920, LC010042, and LC010073, available in GenBank as E. aquilegiae, E. knautiae, and E. euphorbiae, respectively. Pathogenicity tests were done twice on small asymptomatic A. sericifera plants collected in Queensland. In each test, six plants at the 6 to 10 leaf stage were removed from the soil and maintained with their roots in water. Three plants were inoculated by dusting conidia from field collected plants onto the leaves; the three other plants were not inoculated. Plants were maintained separately under transparent plastic covers for 3 weeks. The first symptoms appeared on the inoculated leaves 7 to 10 days post inoculation. All the noninoculated plants remained asymptomatic. Light microscopy and ITS sequencing confirmed the identity of the pathogen. To our knowledge, this is the first report of a conclusively identified Erysiphe sp. infecting A. sericifera globally. So far, powdery mildew has been reported on A. sericifera twice: an unidentified Oidium sp. was listed on this weed in Australia (Simmonds 1966), and Oidium cf. insolitum was reported on A. sericifera in Argentina (Waipara et al. 2006). This latter fungus is very different from any Erysiphe species (Braun and Cook 2012). Several powdery mildews infecting diverse plant species share ITS sequences that are 97 to 99% similar, or identical, to that of E. aquilegiae (Takamatsu et al. 2015), just like the fungus reported here. This group needs a taxonomic re-evaluation (Takamatsu et al. 2015). Also, additional studies are needed to determine the host range of this Erysiphe sp. and its impact on A. sericifera populations.

Erysiphe azerbaijanica and E. linderae: Two new powdery mildew species (Erysiphales) belonging to the Microsphaera lineage of Erysiphe

Two new species, Erysiphe azerbaijanica on Castanea sativa and E. linderae on Lindera praecox, both belonging to the Microsphaera lineage of the genus Erysiphe are described based on morphological and molecular data. Erysiphe azerbaijanica is distinguished from other Erysiphe species occurring on Castanea spp. by its cylindrical conidia with a length/width ratio of 2–3.6, longer conidiophore, and foot-cells. Molecular analyses indicated that this species forms a clade of its own, supporting the morphological observations. Molecular phylogenetic analyses showed that E. blasti s. lat. is divided into two genetically differentiated groups associated with different host species. Based on the sequence differences in the 28S rRNA gene and ITS region, connected with differences in the number and length of appendages, the fungus on L. praecox is described as a new species, E. linderae.

Notes on powdery mildews (Erysiphales) in Thailand IV. Erysiphe species on Malvaceae, Menispermaceae, Moraceae, Nyctaginaceae, Polygonaceae, Solanaceae and Urticaceae

This report provides morphological descriptions of powdery mildews found on Malvaceae, Menispermaceae, Moraceae, Nyctaginaceae, Polygonaceae, Solanaceae and Urticaceae and five specimens are identified with ITS rDNA sequences. These include a new species on Boehmeria siamensis (Urticaceae); Pseudoidium schmiedeknechtii on Schoutenia glomerata, Hibiscus floccosus and Urena lobata; Erysiphe kydiae-calycinae on Kydia calycina; E. pseudolonicerae on Cyclea barbata; E. nyctaginacearum on Mirabilis jalapa; E. polygoni on Antigonon leptopus, Muehlenbeckia platyclada and Polygonum odoratum; Pseudoidium cf. neolycopersici on Physalis sp. and Erysiphe species on Ficus subincisa new for Thailand were described. Based on our finding, we make new taxonomic conclusions for E. nyctaginacearum, it is a new combination of Ps. nyctaginacearum found on M. jalapa and Ps. antigononis is a new synonym of E. polygoni found on A. leptopus.

First Report of Powdery Mildew Caused by Erysiphe alphitoides on Euonymus japonica in Korea

HomePlant DiseaseVol. 101, No. 2First Report of Powdery Mildew Caused by Erysiphe alphitoides on Euonymus japonica in Korea PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Powdery Mildew Caused by Erysiphe alphitoides on Euonymus japonica in KoreaH. B. Lee and T. T. T. NguyenH. B. LeeSearch for more papers by this author and T. T. T. NguyenSearch for more papers by this authorAffiliationsAuthors and Affiliations H. B. Lee T. T. T. Nguyen , Division of Food Technology, Biotechnology & Agrochemistry, College of Agriculture & Life Sciences, Chonnam National University, Gwangju 61186, Korea. Published Online:16 Nov 2016https://doi.org/10.1094/PDIS-08-16-1128-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Euonymus japonica, family Celastraceae, is an evergreen shrub native to Korea, China, and Japan that is often used as an ornamental hedge plant. In October 2014, powdery mildew symptoms and signs were observed amphigenously on the leaves of E. japonica in a park in Seoul, Korea. Also, in June 2016, the same symptoms were found on E. japonica plants in a garden in Gwangju (35°10′N, 126°55′E), Korea, showing higher incidence and severity. Diseased leaves showed white colonies, associated with brown spots on the surface due to the presence of a hyperparasite, Ampelomyces quisqualis, and heavily infected young leaves. Voucher specimens were deposited at Environmental Microbiology Laboratory Fungarium, Chonnam National University, Gwangju, Korea, as EML-EJP1, EML-EJP2, and EML-EJP3. Appressoria of the fungus were lobed, and solitary or in opposite pairs. Measurements were made of 20 conidiophores and 50 conidia. Conidiophores were cylindrical, 45.0 to 77.0 × 6.5 to 10.5 μm. Foot cells of the conidiophores were straight to substraight to cylindrical, and followed by 1 to 3 shorter cells. Conidia were formed singly, cylindrical or ellipsoid-cylindrical, and measured 26.5 (–36.5) to 45 × 12 to 18.5 μm with a L/W ratio of 1.8 to 3.3. Short to moderately long germ tubes were produced terminating in lobed appressoria. The teleomorph was not found. Morphological characters were consistent with anamorphic Erysiphe species. To identify the fungus at the species level, mycelia and conidia of four samples from Euonymus japonica were collected with a sterile needle under a stereomicroscope. rDNA was extracted from mycelia and conidia using the Higene Genomic DNA Prep Kit for fungi (Biopact Corp., Korea). The internal transcribed spacers (ITS1 and ITS2) and 5.8S gene was amplified using primers ITS1F (5′-CTTGGTCATTTAGAGGAAGT-3′) and LR5F (5′-GCTATCCTGAGGGAAAC-3′) as by Lee (2013). A BLASTn search of the rDNA ITS sequences in GenBank indicated that EML-EJP1 (KP325487), EJP2 (KX495611), and EJP3 (KX495610) matched 100% (608/608 bp), 99.6% (766/769 bp), and 99.8% (497/498 bp) with Erysiphe alphitoides (Griffon & Maubl.) Braun & Takam (EF672350, AB257430, and AB292700, respectively). Phylogenetic analysis showed that our strains, EML-EJP1, EJP2, and EJP3, were placed within Alphitoides clade comprising E. alphitoides, E. akebiae, E. menispermi var. dahurica, E. wallrothii, E. sinomenii, and E. euonymicola. Interestingly, when the ITS sequences of our strain and some E. alphitoides were compared with E. euonymicola as a subclade within the Alphitoides clade, there was one base difference between them. The morphological characteristics of our strain completely matched E. alphitoides described by Takamatsu et al. (2007), except for a slight difference in width. The pathogenicity was confirmed by gently pressing the infected leaves onto five leaves of 5-year-old E. japonica plants. Five leaves were inoculated on each plant. The inoculated and noninoculated plants were maintained at 23 ± 2°C with a 12-h photoperiod and 80 to 85% RH. Ten days after inoculation, the symptoms were similar to those observed in the original diseased plants and the fungus on inoculated leaves was morphologically identical to that detected on their leaves, fulfilling Koch’s postulates. No disease developed on the controls. So far, E. euonymicola (formerly Oidium euonymi-japonici) has been found in only Euonymus spp. (Farr and Rossman 2016). In addition, Quercus spp. has been reported as the host of E. alphitoides. Recently, Sorbaria sorbifolia, Wisteria brachybotrys, and W. frutescens have been determined as additional hosts for E. alphitoides (Denton et al. 2016). This information indicates that E. alphitoides is able to infect a wide range of hosts and may pose a threat to multiple woody ornamental plant species. Further studies on the host and geographical ranges of E. alphitoides species are needed. To our knowledge, this is the first report of powdery mildew caused by E. alphitoides on E. japonica in Korea and in the world.

Geographical and spatial distributions of two Erysiphe species occurring on lilacs (Syringa spp.)

Two Erysiphe species, viz., E. syringae and E. syringae-japonicae, are known to occur on lilacs (Syringa spp.). Erysiphe syringae migrated to Europe in the 19th century or early 20th century from the putative geographic origin North America and became widely distributed in Europe by mid-20th. Erysiphe syringae-japonicae was newly introduced to Europe in the 1990s and expanded from eastern Europe westward. Geographic distributions of these Erysiphe species were investigated using PCR restriction fragment length polymorphism (PCR-RFLP) method in Japan and Europe. Only E. syringae-japonicae is distributed on Hokkaido Island, Japan, whereas E. syringae and E. syringae-japonicae coexist in an extended area of Honshu Island. Only E. syringae-japonicae was detected from DNAs extracted from chasmothecia with a few exceptions, suggesting that E. syringae does not produce chasmothecia in Japan. Investigation of samples collected in Europe revealed that E. syringae and E. syringae-japonicae coexist in various regions of Europe. Erysiphe syringae coexists with E. syringae-japonicae on a single lilac leaf without observed spatial differentiation.

Powdery Mildew Caused by an Erysiphe sp. on Korean Ginseng

AbstractIn August and September 2014, Korean ginseng (Panax ginseng) plants showing symptoms of powdery mildew infection were found in a polyethylene film‐covered greenhouse in Suwon, Korea. The mildew was initially observed to occur in circular to irregular white colonies, which subsequently developed into abundant mycelial growths on both leaf surfaces. No chasmothecia were observed. Based on its morphological characteristics, the fungus was determined to be a species of Erysiphe. Phylogenetic analysis of the sequence of the internal transcribed spacer region of the ribosomal DNA obtained from the isolate placed the powdery mildew fungus in the genus Erysiphe. Here, we describe this Erysiphe sp. found growing on Korean ginseng using both illustrations and molecular data. A comparison of the Korean isolate and three previous records of powdery mildews known to grow on Panax plants is also provided. This is the first report of powdery mildew on Korean ginseng in Korea.

Erysiphe viburni-plicati and Podosphaera photiniae, two new species of Erysiphales (Ascomycota) from Japan

Two new species of the Erysiphales, Erysiphe viburni-plicati and Podosphaera photiniae, are described and illustrated in this paper. These two fungi were first reported in 1977 and 1996 as Podosphaera spp. from Japan, but have not yet been formally described and named. We performed detailed morphological re-examinations and phylogenetic analyses based on new specimens. The results clearly show that these fungi are new, hitherto undescribed species. Molecular analyses of E. viburni-plicati indicate that this fungus belongs to the genus Erysiphe, not to Podosphaera, although it has chasmothecia with a single ascus. This result reveals that monoascus-type chasmothecia are not confined to Podosphaera and Cystotheca as they are also formed by some Erysiphe species.

First Report of Oidium anamorph of Erysiphe hypophylla Causing Powdery Mildew on Leafy Lespedeza (Lespedeza cyrtobotrya) in Korea.

Leafy lespedeza (Lespedeza cyrtobotrya Miq.) is a deciduous shrub in the pea family (Fabaceae) that occurs in areas of East Asia including Korea, China, and Japan. It has been commonly used as a fence plant and for sand control in Korea. In late October 2011, a powdery mildew disease was observed on leafy lespedeza in several areas near Gwangju River, Gwangju, Korea. Symptoms appeared late in October when temperature fluctuation was high. Major symptoms included scattered white powdery to cottony colonies on both surfaces of the leaves which spread to stems, causing a minor chlorosis and distortion. Conidia were formed singly on conidiophores with 2 to 4 (commonly 3) septa including basal septum, primary conidia ellipsoid, apex rounded to subtruncate, base truncate; and secondary conidia subcylindrical to oblong when mature, and ends truncate. The size was 26.4 to 43.2 (av. 35.1) × 11.2 to 13.2 (av. 11.3) μm. Conidiophores were erect, cylindrical, wider at apex than foot cell, and straight or slightly flexuous in foot cells. The size was 60.1 to 81.3 (av. 78.1) × 6.2 to 12.1 (av. 8.3) μm. Chasmothecia were not observed. Morphologically, the conidia and conidiophores of our strain (EML-LCPW1) were very similar to those of Erysiphe hypophylla (syn. Microsphaera hypophylla) (4). From extracted genomic DNA, the internal transcribed spacer (ITS) region inclusive of 5.8S and 28S rDNA were amplified with ITS1 (5'-TCCGTAGGTGAACCTGCGG-3'), LR5F (5'-GCTATCCTGAGGGAAAC-3'), LROR (5'-ACCCGCTGAACTTAAGC-3'), and LR5F primer sets, respectively. Based on the morphology and ITS rDNA sequence analysis, the fungus was identified as E. hypophylla. rDNA ITS and 28S homologies of the fungus (EML-LCPW1, GenBank Accession Nos. JX512557 and JX512558) represented 100% (771/771) and 100% (775/775) identity values with E. hypophylla (AB292712 and AB292716, respectively) via NCBI BLASTn search of each isolate. The rDNA ITS (JX512557) and 28S (JX512558) sequence analysis revealed that the causal fungus matched E. hypophylla, forming a HypophyllaAlphitoides clade as Takamatsu et al. suggested that E. hypophylla is conspecific to E. alphitoides (3). So far, it has been known that E. communis, E. glycines var. lespedezae, and E. lespedezae cause powdery mildews on Lespedeza plants in the world (1). In Korea, only one Erysiphe species, E. lespedezae (= E. pisi), has been reported to cause powdery mildew on Lespedeza plants including L. bicolor and L. cyrtobotrya (2). In addition, 10 records with respect to Oidium sp. have been found on Lespedeza spp., including L. cyrtobotrya from Japan and L. chinensis from China (1). However, powdery mildew on Lespedeza plants, including leafy lespedeza caused by E. hypophylla, has not been reported in Korea or elsewhere in the world. This fungus has been reported in association with numerous oak (Quercus) species in nearby countries such as China and Russia (Far East), showing that it may be a potential source of inoculum in Korea as well. To our knowledge, this is the first report of Oidium anamorph of E. hypophylla on leafy lespedeza (L. cyrtobotrya) in Korea.

Erysiphe paracarpinicola: A new species of Erysiphe sect. Uncinula on Carpinus cordata (Betulaceae)

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.

Erysiphe Javanica sp. nov., a New Tropical Powdery Mildew from Indonesia

During the collection of tropical powdery mildews in Cibodas Botanical Garden and Mount Tangkuban Perahu in Indonesia, we found interesting specimens on Castanopsis javanica (Fagaceae). Phylogenetic analysis using a combination of 28S and ITS rDNA sequences clearly showed that this fungus forms a distinct lineage among the Erysiphe species found on hosts of the plant genus Castanopsis. Therefore, we consider this fungus a new species of Erysiphe, described here as Erysiphe javanica. Differences between E. javanica and closely related Erysiphe species are discussed. Mycotaxon, Vol. 120. Hal. 189-194 ISSN 0093-4666

Erysiphe javanica sp. nov., a new tropical powdery mildew from Indonesia

During the collection of tropical powdery mildews in Cibodas Botanical Garden and Mount Tangkuban Perahu in Indonesia, we found interesting specimens on Castanopsis javanica (Fagaceae). Phylogenetic analysis using a combination of 28S and ITS rDNA sequences clearly showed that this fungus forms a distinct lineage among the Erysiphe species found on hosts of the plant genus Castanopsis. Therefore, we consider this fungus a new species of Erysiphe, described here as Erysiphe javanica. Differences between E. javanica and closely related Erysiphe species are discussed.

Two new species of Erysiphe sect. Uncinula (Erysiphales): Erysiphe fernandoae and E. michikoae

Two new species of Erysiphe section Uncinula are described and illustrated based on the molecular and morphological analyses: (1) Erysiphe fernandoae sp. nov. on Fernandoa adenophylla is distinct from other Erysiphe species on the plant family Bignoniaceae by having smaller asci, ca 12 appendages per chasmothecium and being found only in Asia; (2) Erysiphe michikoae sp. nov. on Celtis jessoensis differs from Erysiphe kusanoi on other Celtis species in having smaller chasmothecial, ascal and ascospore dimensions, and fewer number of chasmothecium appendages. The phylogenetic relationships of the two new species with other closely related species are discussed based on 28S and ITS rDNA sequences.

Development of appressoria on conidial germ tubes of Erysiphe species

Modes of branching of appressoria on conidial germ tubes of 36 Erysiphe spp. were studied. Only unlobed appressoria, termed alobatus pattern, were seen in E. lonicerae, E. magnifica and E. symphoricarpi. Viewed from above with light or scanning electron microscopes, other species had ± irregular lobing, but from below in the plane of contact with the substrate successive dichotomous branchings at 120° were seen to produce a five-lobed appressorium within 6h. Each division produced a temporarily dormant outward-facing lobe and an inward limb that continued growth and division to form the axis of curved, hooked, single- or double-headed symmetrical or asymmetrical structures in a helicoid cyme-like pattern. Outlines of extracellular material after removal of germinated conidia confirmed this manner of branching. After 36h some lobes re-divided forming botryose or jigsaw patterns even extending with extra appressoria to form candelabra-like structures. Conidia developed only one true germ tube; rarely secondary unswollen tubes emerged from spare shoulders or ends. The same true germ tubes developed initially on host surfaces, where secondary tubes and/ or extensions from appressorial lobes grew into colonyforming hyphae. Lobed appressoria of Neoerysphe and Phyllactinia also branched at 120°. Podosphaera xanthii exhibited a simpler branching pattern.