Observations on the Morphology of Germ Tubes Produced by Conidia of Powdery Mildew Fungi on the Surface of Water

Mycologia ◽  
1994 ◽  
Vol 86 (5) ◽  
pp. 626 ◽  
Author(s):  
A. Sivapalan
Keyword(s):  
Powdery Mildew ◽  
Powdery Mildew Fungi ◽  
Germ Tubes

scholarly journals First Report of Powdery Mildew on Euphorbia pekinensis Caused by Podosphaera euphorbiae-helioscopiae in China

Plant Disease ◽  
2011 ◽  
Vol 95 (10) ◽  
pp. 1314-1314
Author(s):  
S. Y. Liu ◽  
L. L. Wang ◽  
W. T. Jiang ◽  
Y. Li
Keyword(s):  
Powdery Mildew ◽  
Perennial Grass ◽  
Morphological Characteristics ◽  
28S Rdna ◽  
Direct Sequence ◽  
Internal Transcribed Spacer Region ◽  
Powdery Mildew Fungi ◽  
Germ Tubes ◽  
Euphorbia Pekinensis Rupr ◽  
Taxonomical Study

Euphorbia pekinensis Rupr, the Peking spurge, is a perennial grass that is planted throughout northeast China. Its roots can be used as a Chinese medicine for diuretic or purgative purposes. Some diterpenoids isolated from Euphorbia spp. show strong antitumor, antivirus, skin-irritating, and tumor-promoting activities. Some species contain chemicals that can be used as pesticides. In September and October 2009, spurge plants were seriously infected by powdery mildew fungi in Changchun Agri-Expon, Jilin Province, China. White mildew colonies appeared in early autumn and initial colonies coalesced to cover the entire upper sides of leaves, stems, and petals 3 to 4 weeks after the disease was noticed. Until late October, chasmothecia were observed on leaves and stems and the infected areas also became dark brown. Mycelium was amphigenous, in patches, white, and persistent. Conidia with distinct fibrosin bodies were ellipsoid-cylindrical, 21.6 to 33.8 × 12 to 15.6 μm, and produced in chains. Germ tubes arose near a pole of the conidia and terminated in simple, unlobed apices. Conidiophores were 59.8 to 139.9 μm; foot cells were straight to slightly flexuous, followed by one to three cells, and 24 to 48 × 8.4 to 10.8 μm. Hyphal appressoria were papillate. Chasmothecia were 70 to 95 μm in diameter, averaging 79.4 μm, and were immersed in mycelia. Mycelioid appendages (5 to 12) occurred in the lower part of the chasmothecia and were flexuous, curved, thick walled, and strongly undulate. Appendages were long (349-) 490 to 1,000 (-1,300) μm, averaging 759.4 μm. They were often densely crowded around the chasmothecia. Asci were single, sessile or short stalked, 60 to 80 × 45 to 70 μm, and eight spored. Ascospores were ellipsoid-ovoid and 16.8 to 28.8 × 10.8 to 18 μm. The fungus was identified as Podosphaera euphorbiae-helioscopiae on the basis of morphological characteristics of the anamorphic and teleomorphic stages. An herbarium specimen was deposited in the Herbarium of Mycology of Jilin Agriculture University (CJLCC100). Genomic DNA was extracted from the chasmothecia, and the internal transcribed spacer region (ITS) and the D1/D2 domains of the 28S rDNA were amplified and sequenced (GenBank Nos. JF795490 and JF795491). The ITS sequence has 98% identity with those of Podosphaera lini, P. macularis, and P. spiraeae, and the D1-D2 sequence of 28S rDNA has 99% identity with those of P. negeri and P. spiraeae, which indicated that this fungus belongs to the genus Podosphaera, even though there is no direct sequence evidence that it is P. euphorbiae-helioscopiae. P. euphorbiae-helioscopiae has only been previously reported in Japan (2), occurring on Euphorbia helioscopia. This species is unique because of the long and curved, thick-walled appendages, and there is no comparable species (1). P. euphorbiae-hirtae and P. euphorbiae are reported to infect Euphorbiaceae plants. Both species differ from P. euphorbiae-helioscopiae in their conspicuously shorter appendages (1,3). To our knowledge, this is the first reported occurrence of powdery mildew on E. pekinensis, and P. euphorbiae-helioscopiae is new to China. This is also the first description of the anamorph of the fungus since there is no record in the Erysiphales Database. References: (1) U. Braun. Nova Hedwigia 89:1, 1987. (2) Y. Nomura. Taxonomical Study of Erysiphaceae of Japan. Yokendo LTD, Tokyo, 1997. (3) R. Y. Zheng and Y. N. Yu. Flora Fungorum Sinicorum. Vol. 1. Erysiphales. Science Press, Beijing, 1987.

scholarly journals Bright-Field and Fluorescence Microscopic Study of Development of Erysiphe polygoni in Susceptible and Resistant Bigleaf Hydrangea

Plant Disease ◽  
2009 ◽  
Vol 93 (2) ◽  
pp. 130-134 ◽  
Author(s):  
Yonghao Li ◽  
Mark T. Windham ◽  
Robert N. Trigiano ◽  
Sandra M. Reed ◽  
James M. Spiers ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Hyphal Growth ◽  
Early Response ◽  
Resistance Mechanisms ◽  
Colony Development ◽  
Susceptible Cultivar ◽  
Bright Field ◽  
Erysiphe Polygoni ◽  
Infected Cells ◽  
Germ Tubes

Temporal development of Erysiphe polygoni and responses of bigleaf hydrangeas (Hydrangea macrophylla) to the fungal attack were investigated using bright-field and fluorescence microscopy. Conidia germinated 2 h after inoculation (HAI) and formed primary appressoria at the tip of the primary germ tubes within 4 HAI. Secondary germ tubes were initiated from primary appressoria or other parts of conidia 12 HAI. Hyphae developed through elongation of secondary germ tubes, and paired lateral appressoria were formed along hyphae within 2 days after inoculation (DAI). Conidiophores and conidia were formed 5 DAI. In the susceptible cultivar Nikko Blue and the resistant cultivar Veitchii, the fungus established a parasitic relationship, which was indicated by the formation of haustoria under primary appressoria and development of secondary germ tubes at 1 DAI. A hypersensitive response (HR) and accumulation of callose were detected in both resistant and susceptible cultivars at 3 DAI. Resistance to powdery mildew in Veitchii was evident by manifestation of early accumulation of callose, relatively high percentage of necrotic infected cells, and restricted colony development compared to the susceptible cultivar Nikko Blue. Restricting hyphal growth and sporulation by early response of callose accumulation and HR are important resistance mechanisms that could be used in screening hydrangeas for resistance to powdery mildew.

New records of microcyclic conidiogenesis in some powdery mildew fungi

Mycoscience ◽  
2011 ◽  
Vol 52 (3) ◽  
pp. 213-216 ◽  
Author(s):  
Alexandra Pintye ◽  
Sara Elisabetta Legler ◽  
Levente Kiss
Keyword(s):  
Powdery Mildew ◽  
New Records ◽  
Powdery Mildew Fungi

Checklist of powdery mildew fungi (Erysiphaceae) in Pakistan

Mycotaxon ◽  
2021 ◽  
Vol 136 (3) ◽  
pp. 689-689
Author(s):  
N.S. Afshan ◽  
I. Zafar ◽  
A.N. Khalid
Keyword(s):  
Powdery Mildew ◽  
Species List ◽  
Powdery Mildew Fungi

The 10-page "Checklist of powdery mildew fungi (Erysiphaceae) in Pakistan " by Afshan, Zafar, and Khalid may now be downloaded from Mycotaxon's mycobiota webpage. This annotated species list brings to 149 the number of freeaccess fungae now available on our website: http://www.mycotaxon.com/mycobiota/index.html

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