Powdery Mildew Species Research Articles

First report of Erysiphe bunkiniana from Pakistan

During August–September 2018, powdery mildew symptoms were observed on both surfaces of leaves of Isodon rugosus in the Abbottabad and Malakand districts of Pakistan. The causal agent was identified as Erysiphe bunkiniana, based on its asexual morph and chasmothecia, and its identity was confirmed by molecular data. This is the first Pakistani report of Erysiphe bunkiniana and the first sequence obtained for this powdery mildew species.

First Draft Genome Assemblies of Pleochaeta shiraiana and Phyllactinia moricola, Two Tree-Parasitic Powdery Mildew Fungi with Hemiendophytic Mycelia.

Powdery mildew fungi (Erysiphaceae) are widespread obligate biotrophic plant pathogens. Thus, applying genetic and omics approaches to study these fungi remains a major challenge, particularly for species with hemiendophytic mycelium. These belong to a distinct phylogenetic lineage within the family Erysiphaceae. To date, only a single draft genome assembly is available for this clade, obtained for Leveillula taurica. Here, we generated the first draft genome assemblies of Pleochaeta shiraiana and Phyllactinia moricola, two tree-parasitic powdery mildew species with hemiendophytic mycelium, representing two genera that have not yet been investigated with genomics tools. The Pleochaeta shiraiana assembly was 96,769,103 bp in length and consisted of 14,447 scaffolds, and the Phyllactinia moricola assembly was 180,382,532 bp in length on 45,569 scaffolds. Together with the draft genome of L. taurica, these resources will be pivotal for understanding the molecular basis of the lifestyle of these fungi, which is unique within the family Erysiphaceae.

Diversity of Powdery Mildew Mycoparasite Ampelomyces quisqualis under Natural Ecosystem and Its Molecular Characterization

The powdery mildew are the most common diseases which widely affect crops in many countries. The mildew infection appeared on leaves, petiole, buds, inflorescence and other tender tissues of crops causing 65% of the crop loss. Even though the fungicidal spray to control the disease, the residual and environmental effects are causing long term ecological imbalance in cropping system. Recently, an alternative and eco-friendly mycoparasite associated with powdery mildew pathogens was used against Erysiphe sp, Leveilulla sp, Sphaerotheca sp and Oidium sp. This study aimed to mitigated the use of the expensive and harmful fungicides to save human health and to reduce the financial costs of controlling the fungal infections of crops in the field by using a commercial biofungicide naturally associated with different species of powdery midew fungi. Our results exhibited that the isolation of the mycoparasite Ampelomyces quisqualis from the mildew pathogens was closely associated with most of the genera of powdery mildew pathogens. The natural mycoparasitization efficiency of A. quisqualis was observed and higher (81%) efficiency was recorded in Erysiphe cichoracearum followed by 76% in black gram powdery mildew caused by Erysiphe polygoni. A total of 20 mycoparasitic Ampelomyces isolates were enumerated from pycnidia of 6 different powdery mildew species that naturally infected their host plants. The pycnidial morphological variations of A.quisqualis and the largest size of pycnidia was found in the Erysiphe chichoracearum (73.54µm length × 42.15µm width) shows maximum efficiency in natural parasitization. The molecular characterization of A.quisqualis isolates based on using rDNA ITS region was carried out and sequenced. The phylogenetic analysis was performed using the Maximum likelihood technique was shown the distinct relatedness with five Ampelomyces isolates made in the present study were clustered. This is the first and detailed study on diversity of Ampelomyces and quantification of natural mycoparasitism of different genera of powdery mildew of A. quisqualis.

First Report of Powdery Mildew Caused by Podosphaera xanthii on Cucurbita ficifolia in Korea.

Cucurbita ficifolia Bouché, called fig-leaf gourd, is a cucurbitaceous climbing plant native to the Americas. During summer and autumn of 2020, almost all of fig-leaf gourds planted in an experimental plot in Jeonju (35°50'54″N, 127°07'46″E), Korea, were found to be infected by a powdery mildew with a 100% disease severity. Symptoms first appeared as white, small, irregular colonies, later coalesced into abundant hyphal growth on both sides of the leaves and young stems. Subsequently premature senescence and poor growth of affected leaves was observed. A voucher specimen was housed in the Korea University herbarium (KUS-F32173). For morphological characterization of the fungus, fresh materials were used for microscopy. Conidiophores (n = 30) were straight, 90 to 190 × 10 to 12 μm and produced three to six immature conidia in chains with a crenate outline. Conidia (n = 30) were ellipsoid-ovoid to barrel-shaped, measured 28 to 38 × 18 to 24 μm with a length/width ratio of 1.3 to 2.0, and contained distinct fibrosin bodies. No chasmothecia were found over the course of the season. The morphological feature of the fungus and the host genus were compatible with those of Podosphaera xanthii (Castagne) U. Braun & Shishkoff (Braun and Cook 2012), a well-known cucurbitaceous powdery mildew. For further confirmation, DNA was extracted from mycelium taken from above mentioned specimen. Internal transcribed spacers (ITS1 and ITS2) and large subunit (LSU) gene of the rDNA were amplified using primer pairs ITS1F/PM6 and PM3/TW14, respectively (Takamatsu and Kano 2001). Newly obtained sequences were registered to the GenBank under the accession numbers OL677355 for ITS and OL677356 for LSU. Our sequences shared 99.54~99.77% identity for ITS (MW559231 and MT250855) and 99.58% for LSU with sequences of P. xanthii (MK357445 and MK357438) in BLAST'n search. Pathogenicity tests were performed twice by pressing method of mycelial patches of the infected leaf onto the young leaves of five healthy fig-leaf gourd plants. Five non-inoculated plants were used as controls. Inoculated leaves started to develop powdery mildew signs after 5 days treatment, whereas the control plants remained symptomless. The fungus on the inoculated plants was morphologically identical to that originally observed on diseased plants, fulfilling Koch's postulates. To date three powdery mildew species have been reported on C. ficifolia (Farr and Rossman 2021). Among these reports, Golovinomyces orontii sensu lato was known from Chile, Mexico, United Kingdom, and Germany, Leveillula taurica from Korea and Podosphaera fuliginea (currently P. xanthii) was recorded Australia and India. To our knowledge, this is the first report of P. xanthii on C. ficifolia in Korea. Since this plant is used as grafting rootstock for preventing soil-borne gummy stem blight of cucumber caused by Didymella bryoniae in Korea (Choi et al. 2009), economic importance of the powdery mildew occurring on leaves of this plant is currently limited. Nevertheless, presence of a powdery mildew could be informative to breeding program of Cucurbita spp. and safe production of C. ficifolia fruits globally.

Simultaneous Detection of Plant- and Fungus-Derived Genes Constitutively Expressed in Single Pseudoidium neolycopersici-Inoculated Type I Trichome Cells of Tomato Leaves via Multiplex RT-PCR and Nested PCR

Type I trichomes of tomato leaves (Solanum lycopersicum Mill. cv. Moneymaker), as outgrowths of the plant epidermis, are suitable for monitoring infection processes of powdery mildew species using a high-fidelity digital microscope (DM) without fungal staining. On the trichomes, tomato powdery mildew (Pseudoidium neolycopersici L. Kiss) isolate KTP-03 produced a maximum of four vigorously elongated hyphae per conidium, which stopped growth approximately 12 days after inoculation. Single trichome cells, invaded by fungal hyphae at various fungal infection stages during the 12-day period after the inoculation of single conidia, were cut at the bases and directly collected with small precision scissors (i.e., microscissors) held by the manipulator under a DM. Subsequently, suc-polymerase chain reaction (PCR) (reverse transcription (RT)-PCR followed by nested (N)-PCR) was conducted to explore gene expression in the infected trichome. We selected intron-containing genes from tomatoes and powdery mildew fungi for the detection of constitutive gene transcripts, namely plasma membrane H+-ATPase (LHA2) and β-tubulin 2 (TUB2) genes. In suc-PCR, a single band from spliced mRNAs of both LHA2 and TUB2 genes were detected, suggesting that both genes were successfully transcribed in single KTP-03-infected trichomes. With combined primers for both LHA2 and TUB2 (multiplex RT-PCR/N-PCR), two bands were detected through the amplification of intron-spliced mRNAs of both genes. Therefore, our single-trichome cell PCR amplification method is effective for detecting the expression patterns of genes from both tomato and powdery mildew fungus. Combinations of digital microscopy, microscissors, and multiplex RT-PCR/N-PCR amplification techniques will be useful for simultaneously analysing the molecular interactions between plants and powdery mildew fungi at the level of single tomato leaf trichome cells. Also, this employed technique will be of benefit in other plant species and crops, possessing leaf trichome cells, to elucidate the molecular interactions between plants and pathogens.

Niche differentiation within a cryptic pathogen complex: climatic drivers and hyperparasitism at multiple spatial scales

Pathogens are embedded in multi‐trophic food webs, which often include co‐occurring cryptic species within the same pathogen complex. Nonetheless, we still lack an understanding of what dimensions of the ecological niche might allow these cryptic species to coexist. We explored the role of climate, host characteristics (tree autumn phenology) and attack by the fungal hyperparasite Ampelomyces (a group of fungi attacking plant pathogens) in defining the niches of three powdery mildew species (Erysiphe alphitoides, E. hypophylla and E. quercicola) within a cryptic pathogen complex on the pedunculate oak Quercus robur at the continental (Europe), national (Sweden and France) and landscape scales (a 5 km2 island in southwestern Finland). Previous studies have shown that climate separated the niches of three powdery mildew species (E. alphitoides, E. hypophylla and E. quercicola) in Europe and two species (E. alphitoides and E. quercicola) in France. In our study, we did not detect a significant relationship between temperature or precipitation and the distribution of E. alphitoides and E. hypophylla present in Sweden, while at the landscape scale, temperature, but not relative humidity, negatively affected disease incidence of E. alphitoides in an exceptionally warm year. Tree variation in autumn phenology did not influence disease incidence of powdery mildew species, and hyperparasite presence did not differ among powdery mildew species at the continental, national and landscape scale. Climate did not affect the distribution of the hyperparasite at the continental scale and at the national scale in Sweden. However, climate affected the hyperparasite distribution in France, with a negative relationship between non‐growing season temperature and presence of the hyperparasite. Overall, our findings, in combination with earlier evidence, suggest that climatic factors are more important than species interactions in defining the niches of cryptic species within a pathogen complex on oak.

Mogućnosti primene biouglja (biochar) u zaštiti bilja od prouzrokovača bolesti

Literature review showed, that the utilization of organic amendments has been proposed to decrease the incidence of plant diseases caused by soilborne pathogens. Biochar can be effective against both soilborne pathogens (e.g. Fusarium spp., Phytophthora spp., Rhizoctonia solani) and airborne (e.g. Botrytis cinerea, different species of powdery mildew). Five different mechanisms have been pro posed to explain biochar disease suppression: (1)-induction of systemic resistance in host plants; (2)enhanced abundance and activities of beneficial microbes, including mycorrhizal fungi; (3)-modification of soil quality in terms of nutrient availability and abiotic conditions such as liming eff ECT; (4)-direct fungitoxic effect of biochar; (5)-sorption of allelopathic, phytotoxic compounds that can directly harm plant roots and thus promote pathogen attacks. Potential side-effects of biochar have been reported, like the possibility of absorbing agrochemicals like herbicides, insecticides and fungicides, thus reducing their efficacy. A lot of investigations on the mechanisms underlying biochar disease suppression, as well as long-term field experiments, are very needed to make biochar a safe, affordable and effective tool for the control of these plant pathogens.

Colletotrichum fioriniae infecting invasive Japanese hop (Humulus scandens) in the United States.

Japanese hop (Humulus scandens) is a non-native, invasive plant that colonizes disturbed riparian areas throughout the eastern United States and Canada, forming dense, monocultural stands that displace native plant communities due to a high reproductive rate, rapid growth, climbing bines, and dense shading (Balogh and Dancza 2008). It is capable of serving as a reservoir for agronomically important plant pathogens, such as the Tomato spotted wilt virus and powdery mildew species that infect commercial hemp and hop fields (Yoon et al. 2018; Weldon et al. 2020). In the spring of 2016, diseased populations of H. scandens were observed along the Monocacy River in Frederick County, Maryland with severe chlorotic and necrotic leaf lesions. Symptomatic leaves were surface sterilized and placed in moist chambers at 25°C for sporulation. Sporulating acervuli, lacking setae, developed on irregular, tan necrotic leaf lesions following 7 to 12 days in a moist chamber (Figure 1). Conidia were hyaline, aseptate, smooth-walled, fusiform to cylindrical with both ends acute (Figure 1B). Conidia measured (n = 100) [L x W; Average (+ Std. Err), range]: 12.42 µm (± 0.10), 8.41 - 14.48 µm; x 3.91 µm (±0.03), 3.03 - 4.91 µm. Monoconidial fungal cultures were obtained by transferring conidia with a sterile glass needle to acidified potato dextrose agar and incubated at 25°C for 2 to 3 days. Based on phenotypic characteristics and conidial morphology and size, the pathogen appeared to belong to the Colletotrichum acutatum complex (Damm et al. 2012). Therefore, six loci (ITS, GADPH, CHS1, HIS3, ACT, and TUB2) were amplified and sequenced from a representative isolate, 16-008, for species characterization (GenBank accessions MW023070 to MW023075) (Damm et al. 2012). For the ITS region and ACT, GADPH, and CHS1 loci, isolate 16-008 was 100% identical to C. fioriniae and shared 99% similarity to TUB2 and HIS3 for multiple accessions of C. fioriniae in GenBank. Gene sequences were aligned, trimmed, concatenated, and analyzed against 32 reference strains, within the C. acutatum complex (Damm et al. 2012). Concatenated loci were used to generate a maximum likelihood phylogeny using W-IQ-TREE (Trifinopoulos et al. 2016). Results from the phylogenetic analysis demonstrated that isolate 16-008 was most genetically similar to C. fioriniae with a bootstrap support of 100% (Figure 2). Based on phenotypic and sequence analyses, isolate 16-008 was identified as C. fioriniae. Humulus scandens seedlings from Maryland (n = 3) were inoculated with a conidia suspension (107 conidia mL-1) with 0.125% Tween 20® and applied with an atomizer until runoff. Inoculated plants were placed in a dew chamber at 25°C for 2 days. Experimental plants were distributed in a mist tent at 25°C with 14 h of light and monitored for 2 weeks. Negative control plants (n = 2) were sprayed with a sterile 0.125% Tween 20® water solution. All inoculated plants were symptomatic by 12 days post inoculation. No symptoms were observed on the mock-inoculated plants. Symptoms were identical to disease field samples. Inoculations were repeated with the same results. Colletotrichum fioriniae was reisolated and confirmed from excised leaf lesions via ITS and ACT sequencing. To our knowledge, this is the first report of C. fioriniae naturally infecting H. scandens within the United States (Farr and Rossman 2020). Future studies will evaluate the host range of this isolate due to the species broad host range and the weed's extensive distribution.

Genome Sequence Resource for Erysiphe necator NAFU1, a Grapevine Powdery Mildew Isolate Identified in Shaanxi Province of China.

Erysiphe necator is an economically important biotrophic fungal pathogen responsible for powdery mildew disease on grapevine. Currently, genome sequences are available for only a few E. necator isolates from the United States. Based on the combination of Nanopore and Illumina sequencing technologies, we present here the complete genome assembly for an isolate of E. necator, NAFU1, identified in China. We acquired a total of 15.93 Gb of raw reads. These reads were processed into a 61.12-Mb genome assembly containing 73 contigs with an N50 of 2.06 Mb and a maximum length of 6.05 Mb. Combining the results of three gene-prediction modules (i.e., an evidence-based gene modeler [EVidenceModeler], an ab initio gene modeler, and a homology-based gene modeler), we predicted 7,235 protein-coding genes in the assembled genome of E. necator NAFU1. This information will facilitate studies of genome evolution and pathogenicity mechanisms of E. necator and other powdery mildew species through comparative genome sequence analysis and other molecular genetic tools.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Phylogeny and taxonomy of powdery mildew caused by Erysiphe species on Lupinus hosts

ABSTRACT The genus Lupinus (Fabaceae) consists of over 250 plant species located throughout the world. Powdery mildew, caused by Erysiphe species, is a common disease infecting these ecologically, ornamentally, and agriculturally important plants. In the present work, we conducted phylogenetic and taxonomic analyses on Erysiphe species colonizing hosts of the leguminous genus Lupinus, using sequences from the internal transcribed spacer (ITS) and 28S genomic regions. Powdery mildews of the genus Erysiphe on Fabaceae are taxonomically intricate and challenging. Therefore, it is necessary to phylogenetically analyze the DNA retrieved from powdery mildew on lupines in a broad context that includes common and allied powdery mildew species that occur on a range of leguminous plants such as Erysiphe astragali, E. baeumleri, E. pisi, and E. trifoliorum. A new species Erysiphe lupini, found in the USA on Lupinus lepidus, L. polyphyllus, and Lupinus sp., is described. Additionally, Erysiphe intermedia (≡ Microsphaera trifolii var. intermedia) has been confirmed as a North American lupine powdery mildew that is a sister species to E. astragali on Astragalus spp. European Erysiphe collections on lupines were often referred to as E. intermedia, but our analyses have shown that they pertain to E. trifoliorum. The E. trifoliorum clade is composed of several species (i.e. E. baeumleri, E. euonymi, E. hyperici, and E. trifoliorum), that cannot be sufficiently resolved based solely on ITS+28S sequences. Morphological and biological differences between the species are discussed and provide evidence that the species concerned should be maintained. Finally, a sequence obtained from a powdery mildew collected in Portugal on the native Lupinus micranthus pertained to the Erysiphe guarinonii clade. This collection is tentatively treated as Erysiphe sp. To fix the application of the species names E. astragali, E. baeumleri (including its synonym E. marchica), and E. intermedia, epitypes have been designated with ex-epitype sequences.

One Crop Disease, How Many Pathogens? Podosphaera xanthii and Erysiphe vignae sp. nov. Identified as the Two Species that Cause Powdery Mildew of Mungbean (Vigna radiata) and Black Gram (V. mungo) in Australia.

Powdery mildew is a significant threat to mungbean (Vigna radiata) and black gram (V. mungo) production across Australia and overseas. Although they have been present in Australia for at least six decades and are easily recognized in the field, the precise identification of the pathogens causing this disease has remained unclear. Our goal was to identify the powdery mildew species infecting mungbean, black gram, and wild mungbean (V. radiata ssp. sublobata) in Australia. The internal transcribed spacer (ITS) and large subunit sequences of the ribosomal DNA and/or morphology of 57 Australian specimens were examined. Mungbean and black gram were infected by two species: Podosphaera xanthii and a newly recognized taxon, Erysiphe vignae sp. nov. Wild mungbean was infected only with P. xanthii. Mungbean and black gram powdery mildew ITS sequences from China, India, and Taiwan revealed the presence of only P. xanthii on these crops despite controversial reports of an Erysiphe species on both crops in India. Sequence analyses indicated that the closest relative of E. vignae is E. diffusa, which infects soybean (Glycine max) and other plants. E. vignae did not infect soybean in cross-inoculation tests. In turn, E. diffusa from soybean infected black gram and provoked hypersensitive response in mungbean. The recognition of a second species, E. vignae, as another causal agent of mungbean and black gram powdery mildew in Australia may complicate plant breeding efforts and control of the disease with fungicide applications.

Phylogeny and taxonomy of the Erysiphe adunca complex (Erysiphaceae, Helotiales) on poplars and willows

Erysiphe adunca s. lat. is a common powdery mildew species, distributed almost worldwide, on hosts of Populus and Salix species. Based on its wide host range and distribution as well as its strong morphological variations, E. adunca s. lat. was previously divided into several species or, alternatively, into varieties. However, comprehensive phylogenetic examinations on the putative monophyly of this species or the existence of a possible E. adunca species complex have not been conducted based on combined morphological and molecular approaches. In this study, we retrieved rDNA (ITS and LSU) sequences of 22 powdery mildew specimens on Populus and Salix spp. collected in China, Germany, Iran, Japan, Russia, and the United States and conducted morphological examinations of these and additional specimens. The morphological and molecular data obtained clearly indicate that E. adunca is a species complex comprised of at least four species., viz., E. adunca s. str. (on Populus spp. in Asia, Europe, and North America), E. capreae, including E. pseudoregularis as a new synonym (on Salix spp., particularly on species in Salix subgen. Vetrix sect. Vetrix in Asia, Europe, and North America), the reinstated E. salicis (on Salix spp. belonging to various subgenera of Salix in Asia and Europe), and E. mandshurica (which has been confirmed as a species of its own on Populus spp., in Asia). In addition to the clear phylogenetic differentiation, the morphology of the asexual and sexual morphs of E. adunca s. str., E. capreae and E. salicis is easily distinguishable. Sequences retrieved from collections on Salix gracilistyla (Uncinula salicis-gracilistylae), a species that was previously considered a variety of Uncinula adunca and Erysiphe adunca, formed a small subclade within the E. salicis clade and are now referred to as Erysiphe salicis var. salicis-gracilistylae comb. nov. Alphitomorpha adunca; Erysiphe capreae and E. salicis are epitypified, and a neotype is designated for Alphitomorpha obtusata, with ex-epitype sequences and, in the latter case, an ex-neotype sequence.

First report of powdery mildew of rainforest spinach (Elatostema reticulatum), native to Australia, caused by Podosphaera xanthii

Powdery mildew-infected rainforest spinach (Elatostema reticulatum) plants were found in Queensland, Australia. Based on morphology and nrDNA ITS sequence analyses, the pathogen was identified as Podosphaera xanthii, a powdery mildew species with a worldwide distribution and a broad host range. This is the first record of P. xanthii infecting E. reticulatum, and the first powdery mildew infection recorded for this native Australian plant.

Phylogeny and taxonomy of Erysiphe species (powdery mildew: Erysiphaceae) occurring on the ash trees (Fraxinus spp.).

The genus Fraxinus (Oleaceae), known as ash trees, currently comprises 43 recognized species that are distributed in temperate and subtropical regions of the northern hemisphere. Two Erysiphe (sect. Uncinula) species have been known on Fraxinus spp. so far. In this study, Fraxinus powdery mildews from different areas of the world were collected to make molecular and morphological analyses. These specimens are divided into three distinct molecular phylogenetic groups, which are distinguishable by their morphology and/or host preference. The powdery mildew occurring on F. apertisquamifera and F. lanuginosa is described as a new species, E. fraxinea. Epitypes are designated for E. fraxinicola and E. salmonii. Applying previous traditional species delimitations, various hosts were shared by E. fraxinicola as well as E. salmonii, but the current analyses strongly suggest strict host specificity among these three powdery mildew species. Evolutionary timing calculated by molecular clock analysis suggests co-evolution of powdery mildews with their Fraxinus hosts.

A new species of Podosphaera sect. Sphaerotheca subsect. Sphaerotheca from India—first report of powdery mildew causing wilting and ultimately death of leaves of Filipendula vestita

Podosphaera filipendulensis, a new teleomorph of powdery mildew was discovered on living leaves of Filipendula vestita (Rosaceae). It is the first species of powdery mildew that causes wilting and ultimately death of apical infected leaves of F. vestita. It is described, illustrated and compared with other Podosphaera species reported on Rosaceae and a key to all species reported on Rosaceae is provided. The phylogeny of this species has been inferred from internal transcribed spacer (ITS) rDNA sequence data. Phylogenetically, P. filipendulensis is close to P. ferruginea var. ferruginea and P. macularis but differs in having larger chasmothecia, smaller peridium cells, shorter, narrower and aseptate appendages, 8-spored asci and smaller ascospores.

Occurrence of Erysiphecorylacearum causing powdery mildew of Corylusavellana in Romania

AbstractErysiphe corylacearum, a species of powdery mildew that parasitizes on Corylus spp., has been detected for the first time in Romania. Shortly after the first European record of this pathogen from Ukraine, it was found in many locations throughout the Romanian Carpathians. Disease symptoms on Corylus avellana, morphological characteristics and molecular data (rDNA internal transcribed spacer region) of this pathogen are provided.

Мучнисторосяные грибы (Erysiphaceae) Ферганской долины (в пределах Узбекистана): первый аннотированный список видов

A first annotated checklist of powdery mildews (Erysiphaceae) recorded from the Fergana Valley (within Uzbekistan) was compiled on the base of original long-term research, revisions of previously collected specimens deposited at Tashkent Mycological Herbarium of the Institute of Botany of Academy of Sciences of Uzbekistan (TASM), and earlier publications of other mycologists and phytopathologists. In total, 67 erysiphaceous species of ten genera on 153 angiosperm host plant species of 100 genera and 37 families have been recorded, including 21 species and 1 variety found for the first time in the Fergana Valley. The most species-rich genera in the investigated area are Leveillula (16 species), Erysiphe (15), Podosphaera (12), Golovinomyces (10), and Phyllactinia (8), whereas the genera Arthrocladiella, Blumeria, and Sawadaea are only represented by a single species per genus. Such a particular taxonomic composition of powdery mildews can be considered typical for Central Asia, especially with regard to the prevailing position of Leveillula. The present checklist contains detailed information about all particular findings for each powdery mildew species: recorded host plant species, typical habitats, collection locations, collection dates, collectors’ names and TASM herbarium specimen numbers. The most common species are Blumeria graminis, Erysiphe cruciferarum, E. trifoliorum, E. polygoni, Golovinomyces artemisiae, Leveillula alhagi, L. cylindrospora, L. lappae, L. papilionacearum, L. picridis, L. taurica, Podosphaera clandestina, P. pannosa, P. xanthii, Phyllactinia babayanii, P. fraxini, and P. moricola; whereas all other powdery mildew species are relatively rare.

Evolution of Disease Severity and Susceptibility in the Asteraceae to the Powdery Mildew Golovinomyces latisporus: Major Phylogenetic Structure Coupled With Highly Variable Disease Severity at Fine Scales.

Pathogen host range and pathogen severity are dependent on interactions with their hosts and are hypothesized to have evolved as products of a coevolutionary arms race. An understanding of the factors that affect host range and pathogen severity is especially crucial in introduced pathogens that infect evolutionarily naïve hosts and cause substantial damage to ecosystems. Powdery mildews are detrimental pathogens found worldwide in managed and natural systems. Golovinomyces latisporus is a powdery mildew species that is especially damaging to plants within Asteraceae and to plants within the genus Helianthus in particular. In this study, we evaluated 126 species within Asteraceae to measure the role of host plant morphophysiological traits and evolutionary history on susceptibility to G. latisporus and disease severity. We observed phylogenetic signal in both susceptibility and severity within and among major clades of the Asteraceae. In general, there was a major phylogenetic structure of host severity to G. latisporus; however, there was some fine-scale phylogenetic variability. Phylogenetic statistical methods showed that chlorophyll content, biomass, stomatal index, and trichome density were not associated with disease severity, thus providing evidence that phylogenetic structure, rather than observed plant morphophysiological traits, is the most reliable predictor of pathogen severity. This work sheds light on the role that evolutionary history plays in plant susceptibility and severity to disease and underscores the relative unimportance of commonly assessed host plant traits in powdery mildew severity.

Molecular data from up to 130‐year‐old herbarium specimens do not support the presence of cherry powdery mildew in Australia

AbstractA strain of Podosphaera clandestina has been highlighted as a priority pest threat to the Australian cherry industry. Australia currently has no records of powdery mildew on cherry (Prunus avium). P. clandestina is reported to cause disease on a range of Rosaceae genera including Crataegus and Prunus; in Australia, P. clandestina has only been recorded on Crataegus. A recent species revision identified Podosphaera cerasi on P. avium as a separate species from P. clandestina. Therefore, a revision of which powdery mildew species is present in Australia on Crataegus is required to inform Australian plant biosecurity. Reference collection specimens from the Victorian Plant Pathology Herbarium (VPRI) recorded as Podosphaera spp. collected between 1889 to 2008 on cherry and three other host plant genera from Australia and overseas were sampled for DNA extraction and next‐generation sequencing (NGS). Sequence data from preserved specimens were successfully mapped to internal transcribed spacer (ITS) sequences of P. clandestina in the strict sense, P. cerasi, and Podosphaera prunicola, and chloroplast matK sequences were used to identify plant hosts. Australian specimens on Crataegus hosts were P. clandestina in the strict sense and specimens on Prunus from the USA were identified as P. cerasi and P. prunicola. The outcome of this study confirmed the powdery mildew on Australian Crataegus specimens to be P. clandestina and none of the cherry powdery mildews (Podosphaera pruni‐avium, P. cerasi, or P. prunicola) are present on Australian specimens in the VPRI collection, which suggests they are not present in Australia.

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.