Single host plant species may harbour more than one species of Peronospora - a case study on Peronospora infecting Plantago.

The genus Peronospora is the largest genus of the oomycetes, fungus-like members of the kingdom Straminipila that also contains amoeboid (e.g., Leukarachnion) and plant-like (e.g., Laminaria) lifeforms. Peronospora species are obligate biotrophic plant pathogens, causing high economic losses in various crops and ornamentals, including Plantago species. Several species of Plantago are used as speciality crops and medicinal plants. In this study, Peronospora species parasitic on Plantago were investigated based on morphology and phylogenetic analyses using two nuclear (ITS, nrLSU) loci and one mitochondrial (cox2) locus. As a result of these investigations, 10 new species are added to the already known Peronospora species on Plantago. Interestingly, it was found that four independent species are parasitic to Plantago major, highlighting that the reliance on the host plant for pathogen determination can be misleading in Peronospora. Taking this into account, morphological and phylogenetic analyses should be conducted as a prerequisite for effective quarantine regulations and phytosanitary measures. Citation: Mu M, Choi Y-J, Kruse J, et al. 2024. Single host plant species may harbour more than one species of Peronospora - a case study on Peronospora infecting Plantago. Persoonia 52: 94-118. https://doi.org/10.3767/persoonia.2024.52.04 .

First Report of Impatiens Downy Mildew Outbreaks Caused by Plasmopara obducens Throughout the Hawai'ian Islands.

Downy mildew of impatiens (Impatiens walleriana Hook.f.) was first reported from the continental United States in 2004. In 2011 to 2012, severe and widespread outbreaks were documented across the United States mainland, resulting in considerable economic losses. On May 5, 2013, downy mildew disease symptoms were observed from I. walleriana 'Super Elfin' at a retail nursery in Mililani, on the Hawai'ian island of Oahu. Throughout May and June 2013, additional sightings of the disease were documented from the islands of Oahu, Kauai, Maui, and Hawai'i from nurseries, home gardens, and botanical park and landscape plantings. Symptoms of infected plants initially showed downward leaf curl, followed by a stippled chlorotic appearance on the adaxial leaf surfaces. Abaxial leaf surfaces were covered with a layer of white mycelia. Affected plants exhibited defoliation, flower drop, and stem rot as the disease progressed. Based on morphological and molecular data, the organism was identified as Plasmopara obducens (J. Schröt.) J. Schröt. Microscopic observation disclosed coenocytic mycelium and hyaline, thin-walled, tree-like (monopodial branches), straight, 94.0 to 300.0 × 3.2 to 10.8 µm sporangiophores. Ovoid, hyaline sporangia measuring 11.0 to 14.6 × 12.2 to 16.2 (average 13.2 × 14.7) µm were borne on sterigma tips of rigid branchlets (8.0 to 15.0 µm) at right angle to the main axis of the sporangiophores (1,3). Molecular identification of the pathogen was conducted by removing hyphae from the surface of three heavily infected leaves using sterile tweezers, then extracting DNA using the QIAGEN Plant DNA kit (QIAGEN, Gaithersburg, MD). The nuclear rDNA internal transcribed spacer was sequenced from each of the three samples bidirectionally from Illustra EXOStar (GE Healthcare, Piscataway, NJ) purified amplicon generated from primers ITS1-O and LR-0R (4). Resultant sequences (GenBank KF366378 to 80) shared 99 to 100% nucleotide identity with P. obducens accession DQ665666 (4). A voucher specimen (BPI892676) was deposited in the U.S. National Fungus Collections, Beltsville, MD. Pathogenicity tests were performed by spraying 6-week-old impatiens plants (I. walleriana var. Super Elfin) grown singly in 4-inch pots with a suspension of 1 × 104 P. obducens sporangia/ml until runoff using a handheld atomizer. Control plants were sprayed with distilled water. The plants were kept in high humidity by covering with black plastic bags for 48 h at 20°C, and then maintained in the greenhouse (night/day temperature of 20/24°C). The first symptoms (downward curling and chlorotic stippling of leaves) and sporulation of the pathogen on under-leaf surfaces of the inoculated plants appeared at 10 days and 21 days after inoculation, respectively. Control plants remained healthy. Morphological features and measurements matched those of the original inoculum, thus fulfilling Koch's postulates. To our knowledge, this is the first report of downy mildew on I. walleriana in Hawai'i (2). The disease appears to be widespread throughout the islands and is likely to cause considerable losses in Hawai'ian landscapes and production settings. References: (1) O. Constantinescu. Mycologia 83:473, 1991. (2) D. F. Farr and A. Y. Rossman. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ July 16, 2013. (3) P. A. Saccardo. Syllogue Fungorum 7:242, 1888. (4) M. Thines. Fungal Genet Biol 44:199, 2007.

First Report of Downy Mildew Caused by Plasmopara halstedii on Black-eyed Susan (Rudbeckia fulgida cv. 'Goldsturm') in Maryland.

The North American perennial black-eyed Susan (Rudbeckia fulgida cv. Goldsturm) is an important nursery crop, prized by gardeners and landscapers for its persistent bloom and ease of cultivation. In September 2013, disease symptoms characteristic of downy mildew were observed from multiple R. fulgida plants at two commercial nurseries in the Maryland counties of Howard and Anne Arundel. Over 100 R. fulgida were affected by this disease in both nurseries, rendering the plants unmarketable and causing a substantial financial loss. Plants exhibited dark necrotic lesions on the adaxial leaf surface, and sporulating masses of white mycelium on the abaxial leaf surface and on the adaxial in extreme infections. Plants were stunted with a reduced number of blooms. Microscopic visualization showed coenocytic mycelium, hyaline sporangiophores (length 261 to 904 µm; = 557 µm; n = 20) that were straight and monopodially branched at right angles with several terminal branchlets. Sporangia were hyaline, ovoid to elliptical with smooth surfaces ( = 31 × 28 µm; n = 50). Based on morphological data, the organism was identified as Plasmopara halstedii (Farl.) Berl. & De Toni in Sacc (2). Voucher specimens were deposited in the U.S. National Fungus Collections (BPI 892792 to 892794). Molecular identification was conducted by extracting genomic DNA from sporangiophores and mycelium tweezed from the surface of three infected plants, with extractions performed using the QIAGEN Plant DNA kit (QIAGEN, Gaithersburg, MD). The large subunit of the nuclear rDNA was amplified by PCR using primers LROR and LR7 (3) and sequenced bidirectionally. BLASTn searches of NCBI GenBank showed that the resultant rDNA sequences (accessions KF927152 to KF927154) shared 99% nucleotide identity with curated P. halstedii sequences, consistent with morphological identification. To confirm pathogenicity, three 3.78-liter (1 gallon) containerized R. fulgida cv. Goldsturm plants were inoculated with a sporangial suspension of 2.4 × 104 sporangia/ml and sprayed until both the upper and lower surface of the leaves were completely covered. One negative control plant was sprayed with deionized water. Plants were placed in clear plastic bags in a growth chamber (20°C, 12-h photoperiod). Disease symptoms were observed 3 days post inoculation on all plants. The control plant was symptomless. Morphological features of the pathogen on the surface of inoculated plants were identical to those observed from the original infected plants. Although P. halstedii on R. fulgida cv. Goldsturm has been previously reported in Virginia in 2006 and Florida in 2004, to our knowledge, this is the first report on R. fulgida cv. Goldsturm in Maryland (1). Black-eyed Susans are widely distributed throughout Maryland's landscape and are a staple plant for gardeners, nurserymen and landscape professionals. Given the destructive nature of this disease, downy mildew has the potential to cause considerable economic losses to the state's ornamental crop industry. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , November 18, 2013. (2) P. A. Saccardo. Syllogue Fungorum 7:242, 1888. (3) R. Vilgalys and M. Hester. J. Bacteriol. 172:4238, 1990.

First Report of Boxwood Blight Caused by Calonectria pseudonaviculata in Delaware, Maryland, New Jersey, and New York.

Boxwood (Buxus spp.) are commercially important evergreen ornamental plants with an annual market value of over $103 million in the United States. The recent U.S. incursion of boxwood blight disease caused by the fungus Calonectria pseudonaviculata (syn. Cylindrocladium pseudonaviculatum, Cy. buxicola) threatens the health and productivity of boxwood in both landscape plantings and nurseries. The first confirmed U.S. reports of the disease were made from Connecticut and North Carolina in November 2011 (2,4), followed by diagnoses in 10 additional states during 2012 and 2013. By August 2013, symptoms consistent with boxwood blight had been observed from B. sempervirens in Delaware, Maryland, New Jersey, and southeastern New York. Affected plants showed rapid onset of disease symptoms: dark brown to black spots or diffuse dark areas on leaves, followed by defoliation. Narrow, elongate black cankers also formed on current season shoots. Symptomatic stems and leaves were placed in petri dishes with moistened filter paper at 22°C for 3 days under continuous light. Conidiophores were excised, then placed on potato dextrose agar amended with streptomycin and neomycin (0.3 g/l). Resultant colonies showed dark brown pigmentation at the colony center surrounded by tan to reddish brown rings with white mycelia at the advancing edge. Conidia (n = 30 per isolate) were hyaline, cylindrical, rounded at both ends, with a single septum (45 to 76 × 4 to 6 µm; avg. 63 × 5 µm). Conidiophores (n = 20 per isolate) comprised a stipe, a hyaline septate stipe extension (length 119 to 192 µm; avg. 150 µm) and a terminal ellipsoidal vesicle (diameter 4 to 10 µm; avg. 7 µm). Based on morphological characteristics, the causal agent was identified as C. pseudonaviculata (1,4). Voucher specimens were deposited in the U.S. National Fungus Collections (BPI 892698 to 701). To verify morphological diagnosis, genomic DNA was extracted from fungal biomass grown in liquid cultures of yeast extract peptone dextrose media. A portion of the ß-tubulin gene (TUB2) was PCR amplified and sequenced bi-directionally using primers Bta/Bt2b (3). BLASTn searches of NCBI GenBank databases using the TUB2 sequences (Accession Nos. KF785808 to 11) demonstrated 96 to 100% sequence identity with other C. pseudonaviculata isolates. To confirm pathogenicity, 5-month-old B. sempervirens and B. microphylla seedlings were spray-inoculated with a spore suspension of 1 × 104 conidia/ml. One isolate from each state was independently tested with four replicates each. Non-inoculated water-sprayed plants served as negative controls. Plants were maintained in growth chambers at 22°C under constant light. Blight symptoms developed 4 to 5 days post inoculation. C. pseudonaviculata was re-isolated from inoculated plants; no symptoms or signs were observed from control plants. To our knowledge, this is the first report of C. pseudonaviculata in the states of Delaware, Maryland, New Jersey, and New York. This report demonstrates that C. pseudonaviculata is now widespread across the United States eastern seaboard, and represents a substantial threat to boxwood plants in North American landscapes and nurseries. References: (1) P. Crous et al. Sydowia 54:23, 2002. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, USDA-ARS. Retrieved from http://nt.ars-grin.gov/fungaldatabases , 30 August 2013. (3) N. L. Glass and G. C. Donaldson. Appl. Environ. Microbiol. 61:1323, 1995. (4) K. L. Ivors et al. Plant Dis. 96:1070, 2012.

Peronosporaceae species causing downy mildew diseases of Poaceae, including nomenclature revisions and diagnostic resources.

Downy mildew pathogens of graminicolous hosts (Poaceae) are members of eight morphologically and phylogenetically distinct genera in the Peronosporaceae (Oomycota, Peronosporales). Graminicolous downy mildews (GDMs) cause severe losses in crops such as maize, millets, sorghum, and sugarcane in many parts of the world, especially in tropical climates. In countries where the most destructive GDMs are not endemic, these organisms are often designated as high-risk foreign pathogens and subject to oversight and quarantine by regulatory officials. Thus, there is a need to reliably and accurately identify the causal organisms. This paper provides an overview of the Peronosporaceae species causing graminicolous downy mildew diseases, with a description of their impact on agriculture and the environment, along with brief summaries of the nomenclatural and taxonomic issues surrounding these taxa. Key diagnostic characters are summarized, including DNA sequence data for types and/or voucher specimens, morphological features, and new illustrations. New sequence data for cox2 and 28S rDNA markers are provided from the type specimens of three species, Peronosclerospora philippinensis, Sclerospora iseilematis, and Sclerospora northii. Thirty-nine species of graminicolous downy mildews are accepted, and seven previously invalidly published taxa are validated. Fifty-five specimens are formally designated as types, including lectotypification of 10 species, neotypification of three species, and holotype designation for Sclerophthora cryophila. Citation: Crouch JA, Davis WJ, Shishkoff N, Castroagudín VL, Martin F, Michelmore R, Thines M (2022). Peronosporaceae species causing downy mildew diseases of Poaceae, including nomenclature revisions and diagnostic resources. Fungal Systematics and Evolution 9: 43-86. doi: 10.3114/fuse.2022.09.05.

First Report of Anthracnose Disease of Ornamental Feather Reed Grass (Calamagrostis × acutifolia 'Karl Foerster') Caused by Colletotrichum cereale.

Calamagrostis × acutifolia 'Karl Foerster' (feather reed grass) is a cool-season grass grown extensively as an ornamental plant throughout the United States. In July 2005, severe foliar damage was observed in feather reed grasses in a residential garden in Barrington, NJ. Symptoms were observed as small, yellowish brown, oval to irregularly shaped spots on the blades, with spread and coalescence of spots leading to eventual necrosis and plant death. Numerous acervuli with black setae diagnostic of fungi in the genus Colletotrichum were present on necrotic lesions. Two distinct fungi were isolated from diseased tissue by plating small sections of infested leaf tissue on potato dextrose agar (PDA) supplemented with 40 µg/liter each of penicillin, ampicillin, gentomycin, and streptomycin. The first fungus was identified as Colletotrichum gloeosporioides based on morphological, cultural (2), and molecular characteristics. Variable colonies of gray-white mycelia with masses of pink-to-salmon hued conidia formed at 25°C on PDA under constant light. Conidia were hyaline, aseptate, straight, and cylindrical with rounded apices (11.0 to 18.5 × 2.5 to 5.0 µm). Sequencing of the internal transcribed spacer (ITS) rDNA region showed the fungus to be most similar to C. gloeosporioides (GenBank Accession No. EU979125). The second fungus was identified as C. cereale based on morphological, cultural, and molecular characteristics (1). Variable colonies of gray-tan-white mycelia formed at 25°C on PDA under constant light and salmon-colored conidial masses surrounded numerous setae. Conidia were hyaline, aseptate, falcate, fusiform, and guttulate (15.0 to 21.5 × 2.5 to 4.5 µm). Hyphal appressoria were ovoid, sometimes lobate or multilobate (10.5 to 13.5 × 7.5 to 10.0 µm). Maximum likelihood phylogenetic analysis of the ITS sequence (GenBank Accession No. DQ126193) and fungal mating type idiomorph Mat1-2 HMG box (GenBank Accession No. DQ131962) identified the fungus as C. cereale (1). Pathogenicity was determined by inoculating healthy feather reed grasses (11.4-liter pots) established 61 cm off-center in a mulched bed. Three replicate plants per treatment were sprayed with a 20-ml conidial solution (5 × 104 conidia/ml in 0.1 potato dextrose broth) of either C. cereale or C. gloeosporioides and an uninoculated control. Temperatures ranged from 19 to 36°C and humidity varied between 31 and 79%. No symptoms were observed in uninoculated controls or plants inoculated with C. gloeosporioides. Plants inoculated with C. cereale developed disease symptoms within 21 days; the fungus was subsequently reisolated from symptomatic leaves and confirmed as C. cereale. To our knowledge, this is the first report of anthracnose of feather reed grass caused by C. cereale (formerly known as C. graminicola). Although C. cereale is known to inhabit numerous cool-season grass hosts, this is the first description of this fungus as a pathogen of an ornamental grass. Given the recent emergence of anthracnose epidemics caused by C. cereale on golf course turfgrass, the identification of this fungus as a pathogen of Calamagrostis × acutifolia highlights the need for nurseries and regulatory personnel to screen ornamental grasses such as feather reed grass for the presence of C. cereale so that the disease does not become problematic. References: (1) J. A. Crouch et al. Phytopathology 96:46, 2006. (2) B. C. Sutton. The genus Glomerella and its anamorph Colletotrichum in: Colletotrichum: Biology, Pathology and Control. J. A. Bailey and M. J. Jeger, eds. CAB International, Wallingford, UK, 1992.

First Report of Colletotrichum cereale Causing Anthracnose Foliar Blight of Creeping Bentgrass in Mississippi and Alabama.

Colletotrichum cereale Manns, formerly C. graminicola (Ces.) G.W. Wils., is the causal agent of anthracnose foliar blight (AFB) of creeping bentgrass (Agrostis stolonifera L.) and other grass species (1). AFB is most prevalent on creeping bentgrass during summer heat stress (2). Symptoms of AFB progress from older to younger leaves with leaf tips becoming chlorotic and eventually developing complete leaf necrosis. Symptoms in turf stands appear as yellow-to-bronze, irregularly shaped patches often associated with a loss of turf density (2). When C. cereale is actively infecting the foliar tissue, appressoria can be observed microscopically in the leaf sheaths of creeping bentgrass. C. cereale colonizes the foliar tissue, producing abundant acervuli, where conidia and setae develop. Creeping bentgrass samples exhibiting symptoms of AFB were collected from West Point, MS and Birmingham, AL in July 2006. Symptomatic plants with signs of C. cereale were surface disinfested and plated onto one-quarter-strength potato dextrose agar (PDA). Monoconidial C. cereale isolates were grown on full-strength PDA for 21 days at 25°C under fluorescent lights. Single-celled conidia were mostly falcate, ranged from 13.1 to 25.6 µm long × 3.6 to 6.3 µm wide, and averaged 22.2 × 4.7 µm. Hyphal appressoria were irregularly shaped and heavily lobed, ranging from 5.6 to 16.1 µm long × 4 to 10.6 µm wide, and averaged 12.1 × 7.9 µm. In culture, setae were acicular, five to seven septate, thick walled, ranged from 74 to 213.5 µm long, and averaged 151.3 µm. The morphological characteristics of 44 AFB isolates were similar to those of C. cereale reported by Crouch et al. (1). Nucleotide sequences were generated for the internal transcribed spacer rDNA for isolates OO7-T42, OW15-H32, and 04-111 (GenBank Accession Nos. EU859957, EU859958, and EU859959). Maximum likelihood-based phylogenetic analyses of these sequences with authentic isolates of Colletotrichum species from grass hosts (2) indicated that all three isolates were C. cereale. 'Penn A-1' creeping bentgrass seedlings (10.16-cm pots) were inoculated with the C. cereale isolates OO7-T42, OW15-H32, or 04-111 by spraying a conidial suspension (1.5 × 105 conidia/ml) on plants until water droplets were evident within the canopy. An uninoculated control sprayed with distilled water only was used for comparison. Three replicates per C. cereale isolate were included simultaneously when performing Koch's postulates. The inoculated creeping bentgrass seedlings were placed in covered plastic boxes to maintain humidity and incubated under 12 h of fluorescent light with day/night temperatures at 35/28°C. After 4 days, the covers were removed and creeping bentgrass was maintained an additional 14 days until symptoms and signs were observed on the foliage. C. cereale was reisolated from inoculated creeping bentgrass exhibiting symptoms of AFB for all three isolates used. No acervuli, setae, or conidial masses were observed on uninoculated control plants. To our knowledge, this is the first report of C. cereale causing AFB on creeping bentgrass in Mississippi and Alabama. References: (1) J. A. Crouch et al. Phytopathology 96:46, 2006. (2) R. W. Smiley et al. Compendium of Turfgrass Diseases. The American Phytopathological Society, St. Paul, MN, 2005.

A psychometric analysis of the California Card Sorting Test.

The purpose of this study is to begin to characterize performance on the California Card Sorting Test (CCST), a relatively new measure of executive function specifically designed to fractionate problem-solving ability into its cognitive components. Data describing the performance of 135 neurologically intact young adults on the CCST and four other common measures of executive function are presented. Factor analyses indicated that the CCST is a valid measure of concept formation and abstract ability and that the CCST taps abilities different from those measured by commonly used tests of executive function. While further work must be done, the CCST seems to hold promise as a neuropsychological assessment instrument.

The California Card Sorting Test may dissociate verbal and non-verbal concept formation abilities.

Most neuropsychological measures of executive function provide only global indices of performance and are relatively insensitive to lateralized dysfunction. The present paper presents a right temporal lobectomy patient whose performance indicates that the California Card Sorting Test, a new measure of executive function, may dissociate verbal and non-verbal concept formation abilities. This case highlights the potential research and clinical value of this test compared to that of existing tests of executive function.

Factorial structure of the Wisconsin Card Sorting Test.

This study examined the factorial structure of the Wisconsin Card Sorting Test (WCST) in normal university students (N = 135) and a mixed clinical sample (N = 139). Two highly stable orthogonal factors were observed accounting for 70 and 21 per cent of the variance, respectively. Factor I was interpreted as reflecting undifferentiated executive function while Factor II may measure cognitive abilities associated with attentional function. This work can serve as the basis for further examination of the construct validity of the WCST and has implications for its use.

Impact of childhood rape and aggravated assault on adult mental health.

Associations among childhood assault (rape, aggravated assault, or both) and indices of adult mental health (posttraumatic stress disorder, major depressive episode) were examined in a national probability sample of 4,008 (weighted) women. Relationships among assault characteristics and these adult mental health indices were also investigated. Findings suggested particularly deleterious effects for childhood aggravated assault and rapes that caused additional physical injury.

Humoral immunostimulation. VIII. Increased incorporation of phosphate and turnover of phosphatidylinositol in cells treated with antibody.

Uptake of phosphate (32P) in L cells was modulated by reaction with anti-L cell antibody. A biphasic response was noted with high, cytotoxic concentrations inhibiting 32P uptake and low, cytostimulatory concentrations stimulating 32P uptake. Stimulation of 32P uptake was dependent upon multivalent binding as immune IgG and F(ab')2 were effective, but univalent Fab' was ineffective in enhancing 32P uptake into cells. Antibody stimulation of 32P uptake appeared to be an energy independent process and to take place by activation of 32P membrane transport with an increased Vmax (19.3 pmoles/min to 25.3 pmoles/min), but the same Km (0.22 mM). Isolation and measurement of cellular (primarily membrane) phospholipids demonstrated a dramatic increase of (2-fold) specific radioactivity in phosphatidylinositol. Early turnover of phosphatidylinositol may be an important signal for tumor cells to grow at an enhanced rate when exposed to cytostimulatory concentrations of antibody.

Classification accuracy of the portland digit recognition test in traumatic brain injury.

This study examined the classification accuracy of the Portland Digit Recognition Test (PDRT) in traumatic brain injury (TBI). It differs from past studies in assigning patients to malingering and control groups on the basis of compensation-seeking status and the presence of external markers for malingering. Sensitivity and Specificity were.77 and 1.00, respectively. Past research comparing compensation-seekers to noncompensation-seekers reported Sensitivities of.33 or lower (Specificity is always high). This study demonstrates that past research has seriously underestimated the Sensitivity of the PDRT and raises questions about the true Sensitivity of other malingering techniques as well.

Selected cases of poor outcome following a minor brain trauma: comparing neuropsychological and positron emission tomography assessment.

Neuropsychological residua are common particularly in the early stages following a minor traumatic brain injury (TBI), however, a minority of individuals complain of persistent deficits following months or years post-accident. Nine such cases are presented with little or no evidence of brain damage demonstrated according to non-functional neuroimaging (for example CT, MRI), yet their neuropsychological examinations were positive. Since the introduction of positron emission tomography (PET), which captures a functional approach, the question arose as to what extent the two techniques (i.e. PET and neuropsychological examination) are interrelated. All nine minor TBI cases revealed a corroboration between the positive neuropsychological findings confirmed on the PET. The PET procedure documented neuropathology which frequently was pronounced in the frontal and anteriotemporo-frontal regions. Moreover, no significant differences were evident between those five cases with reported loss of consciousness vs. those four cases without.