Characterization of Powdery Mildew Caused by Leveillula taurica on Calla Lily in California

Spring calla lily (Zantedeschia spp.), also known as colored or miniature calla, has markedly increased in popularity in recent years, and the production acreage in the central coast counties of California (Monterey, Santa Cruz, and San Benito), therefore, has significantly increased. Commercial plantings of calla lily (Z. albo maculata and Z. rehmannii hybrids) in California have been infected with a powdery mildew for several years, with the disease particularly evident in late summer and fall. In 2001, powdery mildew was again prevalent, and the pathogen was examined in detail. Initial symptoms consisted of chlorotic, circular-to-oval leaf lesions with diffuse margins. As the disease progressed, white sporulation became visible on lesions. In advanced stages of the disease, the center tissue of lesions turned necrotic. For any such lesion, both the corresponding adaxial and abaxial sides of the leaf always exhibited the symptoms of the disease and developed sporulation of the pathogen. Epidermal strips from both sides of leaves and leaf cross sections were mounted in drops of lactophenol and aniline blue and examined with a light microscope. These preparations showed that epiphytic mycelium was absent and all conidiophores developed from endophytic mycelium and emerged through stomata. Conidiophores carried single or sometimes two conidia and were sometimes branched. Hyaline, single-celled conidia were dimorphic. Primary (terminal) conidia were lanceolate with distinct apical points and measured (58-) 67 to 78 (-81) × 14 to 22 μm. Secondary conidia were ellipsoid-cylindric and measured (56-) 58 to 72 × 17 to 22 μm. For both conidial types, length to width ratios were greater than three. Based on these characters, the pathogen was identified as Leveillula taurica (anamorph Oidiopsis taurica). Cleistothecia were not observed. To test whether the calla lily pathogen could infect another known host of L. taurica, diseased calla lily leaves were gently pressed against leaves of potted tomato (Lycopersicon esculentum) plants (2). Inoculated tomato plants were kept in a humidity chamber for 48 h and maintained in a greenhouse (24 to 26°C). After 12 days, chlorotic lesions appeared on inoculated tomato leaves, and sporulation of L. taurica was observed on the lesions. Uninoculated control tomato plants did not develop powdery mildew. To our knowledge, this is the first report of powdery mildew, caused by L. taurica, on calla lily in North America. This disease has been reported on calla lily in South Africa, Spain, Taiwan, Turkey, and Zimbabwe (1,3,4). References: (1) Y.-K. Chen et al. Ann. Phytopathol. Soc. Jpn. 62:580, 1996. (2) J. C. Correll et al. Plant Dis. 71:248, 1987. (3) K. A. Hirata. Host Range and Geographic Distribution of the Powdery Mildew Fungi. Japan Scientific Society Press, Tokyo, 1986. (4) E. Sezgin et al. J. Turkish Phytopathol. 13:111, 1984.

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Powdery Mildew, Caused by Leveillula taurica, on Matilija Poppy in California

Plant Disease ◽

10.1094/pdis-91-3-0329a ◽

2007 ◽

Vol 91 (3) ◽

pp. 329-329

Author(s):

S. T. Koike

Keyword(s):

Powdery Mildew ◽

Cross Sections ◽

Northern Mexico ◽

Leveillula Taurica ◽

Landscape Plants ◽

Initial Symptoms ◽

Humidity Chamber ◽

Advanced Stages ◽

Symptoms And Signs

Romneya coulteri, known as matilija poppy or coulter's matilija poppy, is a perennial woody shrub (family Papaveraceae) that is native to southern California and northern Mexico. The plant is used in landscape settings and has the largest flowers, measuring up to 16 cm across, of any plant native to California. In August 2006, in Monterey County, CA, landscape plants of R. coulteri were found affected with a powdery mildew disease. Initial symptoms consisted of chlorotic, irregularly shaped, vein-delimited lesions. As disease progressed, grayish white sporulation was visible on lesions on adaxial and abaxial sides of affected leaves. In advanced stages of the disease, lesions expanded up to 2 cm long and the center tissue of the lesions turned necrotic. Symptoms and signs were observed on both mature and younger foliage. The small matilija poppy planting consisted of six or seven plants and all plants were affected by the disease. Epidermal strips from both sides of leaves and leaf cross sections were mounted in drops of lactophenol and aniline blue and examined with a light microscope. These preparations showed that conidiophores developed from endophytic mycelium and emerged through stomates. Conidiophores were sometimes branched and carried one or two conidia. Hyaline, single-celled conidia were dimorphic. Primary (terminal) conidia were lanceolate with distinct apical points and measured 53 to 61 × 17 to 25 μm. Secondary conidia were ellipsoid-cylindric and measured 53 to 67 × 16 to 22 μm. On the basis of these characters, the pathogen was identified as Leveillula taurica (1). Only the anamorph Oidiopsis taurica stage was observed on plants. To prove pathogenicity, diseased leaves were collected from the landscape plantings. One diseased leaf was gently rubbed against one leaf of a potted, healthy matilija poppy. Twelve leaves were inoculated in this way, and plants were kept in a humidity chamber for 48 h and then maintained in a greenhouse (24 to 26°C). After 14 days, chlorotic lesions appeared on inoculated matilija poppy leaves and sporulation of L. taurica was observed several days later. Untreated control plants did not develop powdery mildew. The experiment was repeated and the results were the same. To my knowledge, this is the first report of powdery mildew caused by L. taurica on matilija poppy. There was no indication that the disease affected the growth of the host; however, powdery mildew reduced the quality of the appearance of this ornamental plant. Reference: (1) H. J. Boesewinkel. Bot. Rev. 46:167, 1980.

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Ecological Basis of the Interaction betweenPseudozyma flocculosaand Powdery Mildew Fungi

Applied and Environmental Microbiology ◽

10.1128/aem.01255-10 ◽

2010 ◽

Vol 77 (3) ◽

pp. 926-933 ◽

Cited By ~ 16

Author(s):

Walid Hammami ◽

Candy Quiroga Castro ◽

Wilfried Rémus-Borel ◽

Caroline Labbé ◽

Richard R. Bélanger

Keyword(s):

Powdery Mildew ◽

Fluorescent Protein ◽

Close Relative ◽

Tomato Plants ◽

Powdery Mildews ◽

Biocontrol Activity ◽

Cellobiose Lipids ◽

Powdery Mildew Fungi ◽

Green Fluorescent ◽

Ecological Basis

ABSTRACTIn this work, we sought to understand how glycolipid production and the availability of nutrients could explain the ecology ofPseudozyma flocculosaand its biocontrol activity. For this purpose, we compared the development ofP. flocculosato that of a close relative, the plant pathogenUstilago maydis, under different environmental conditions. This approach was further supported by measuring the expression ofcyp1, a pivotal gene in the synthesis of unique antifungal cellobiose lipids of both fungi. On healthy cucumber and tomato plants, the expression ofcyp1remained unchanged over time inP. flocculosaand was undetected inU. maydis. At the same time, green fluorescent protein (GFP) strains of both fungi showed only limited green fluorescence on control leaves. On powdery mildew-infected cucumber leaves,P. flocculosainduced a complete collapse of the pathogen colonies, but glycolipid production, as studied bycyp1expression, was still comparable to that of controls. In complete contrast,cyp1was upregulated nine times whenP. flocculosawas applied toBotrytis cinerea-infected leaves, but the biocontrol fungus did not develop very well on the pathogen. Analysis of the possible nutrients that could stimulate the growth ofP. flocculosaon powdery mildew structures revealed that the complex Zn/Mn played a key role in the interaction. Other related fungi such asU. maydisdo not appear to have the same nutritional requirements and hence lack the ability to colonize powdery mildews. Whether production of antifungal glycolipids contributes to the release of nutrients from powdery mildew colonies is unclear, but the specificity of the biocontrol activity ofP. flocculosatoward Erysiphales does appear to be more complex than simple antibiosis.

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Studies of the powdery-mildew fungus, Leveillula taurica, on green pepper. II. Light and electron microscopic observation of the infection process

Canadian Journal of Botany ◽

10.1139/b79-296 ◽

1979 ◽

Vol 57 (22) ◽

pp. 2501-2508 ◽

Cited By ~ 14

Author(s):

Hitoshi Kunoh ◽

Mitsuru Kohno ◽

Sadayoshi Tashiro ◽

Hiroshi Ishizaki

Keyword(s):

Powdery Mildew ◽

Light And Electron Microscopy ◽

Host Cells ◽

Outer Cell ◽

Lipid Bodies ◽

Powdery Mildew Fungus ◽

Green Pepper ◽

Ultrastructural Studies ◽

Leveillula Taurica ◽

Powdery Mildew Fungi

Almost all ultrastructural studies of powdery-mildew fungi have been focused on the epiparasitic fungi. In this paper, one of the endoparasitic powdery-mildew fungi, Leveillula taurica (Lev.) Arn., on green pepper (Capsicum annuum L. var. angulosum Mill.) leaves was investigated by light and electron microscopy. Most germinated conidia formed a lobed adhesion body (similar to the appressorium in morphology but different in function) before stomatal invasion. The track of the adhesion body on the leaf epidermis was depressed, and no cuticular perforations were observed in it. After stomatal invasion, infection hyphae grew extensively into the intercellular spaces of the leaves and formed haustoria in the spongy- and palisade-parenchyma cells. The haustorium was flask shaped with a neck arising from the intercellular hypha. The overall profiles of the haustorium resembled those of epiphytic powdery-mildew fungi of other authors; the haustorium was composed of a nucleate central body and many anucleate lobes, and the entire structure was bounded by an extrahaustorial membrane. Papillae consisting of three distinct regions formed against the outer cell walls at the site of penetration. The most obvious alteration in infected host cells was a marked increase in the number of large lipid bodies. Lipid bodies increased in number with time after haustorial formation. They appeared first in the host cytoplasm near the extrahaustorial membrane, then in the extrahaustorial matrix and haustorial body.

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First Report of Powdery Mildew on Potato Caused by Leveillula taurica in North America

Plant Health Progress ◽

10.1094/php-2004-1214-01-hn ◽

2004 ◽

Vol 5 (1) ◽

pp. 15 ◽

Cited By ~ 4

Author(s):

Dean A. Glawe ◽

Lindsey J. du Toit ◽

Gary Q. Pelter

Keyword(s):

North America ◽

Middle East ◽

Powdery Mildew ◽

Russet Burbank Potato ◽

Russet Burbank ◽

The Other ◽

Leveillula Taurica ◽

Powdery Mildew Fungi ◽

First Time ◽

Made In

In August 2004, examination of powdery mildew-infected ‘Russet Burbank’ potato leaves from a furrow-irrigated field in Grant Co., WA, revealed two powdery mildew fungi, one referable to Erysiphe orontii and the other to Leveillula taurica (Lév.) G. Arnaud. Discovery of the two species sporulating together on diseased leaves is consistent with an observation made in the Middle East. This report documents, for the first time, L. taurica on potato in N. America and provides information on distinguishing it from E. orontii. Accepted for publication 9 December 2004. Published 14 December 2004.

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