Venturia Sacc.

Syll. fung. (Abellini) 1: 586. 1882.

• Synonyms: Fusicladium Bonord., Handb. Mykol.: 80. 1851.
• Apiosporina Höhn., Sitzungsber. Kaiserl. Akad. Wiss., Math.-Naturw. Cl., Abt. 1, 119: 439. 1910.
• Metacoleroa Petr., Ann. Mycol. 25: 332. 1927.
• Caproventuria U. Braun, A Monograph of Cercosporella, Ramularia and Allied Genera (Phytopathogenic Hyphomycetes) 2: 396. 1998.
• Pseudocladosporium U. Braun, A Monograph of Cercosporella, Ramularia and Allied Genera (Phytopathogenic Hyphomycetes) 2: 392. 1998.
• Classification: Dothideomycetes, Pleosporomycetidae, Venturiales, Venturiaceae. 
• Type species: Venturia inaequalis (Cooke) G. Winter. Type material in Kew: IMI 47413.
• DNA barcode (genus): LSU. 
• DNA barcodes (species): ITS, tef1, tub2.

Ascomata pseudothecial, globose, subglobose, black, initially immersed, becoming erumpent, solitary, scattered or gregarious, covered with setae; ostiole central, papillate; ascomatal wall composed of a few layers of pigmented cells of textura angularis, which is of equal thickness or slightly thickened at apex. Hamathecium comprising septate, filiform pseudoparaphyses, evanescent in mature ascomata. Asci bitunicate, oblong to obclavate, fissitunicate dehiscence unknown, with or without a short, thick pedicel, rounded at the apex with an inconspicuous ocular chamber. Ascospores obliquely uniseriate, partially overlapping to biseriate, especially at the base, ellipsoidal, with broadly rounded ends, pale brown, 1-septate, slightly constricted at the septum, the upper cell shorter than the lower one, smooth-walled. Conidiophores single, sometimes arranged in small groups, straight to flexuous, pale olivaceous to dark brown, unbranched or occasionally branched, thin- to slightly thick-walled, conidiophores often reduced to conidiogenous cells or composed of several cells. Conidiogenous nodes smooth to verruculose. Conidia in simple or branched acropetal chains, ellipsoid-ovoid, obovoid, fusoid, obclavate-subcylindrical, canoe-shaped, straight to curved, subhyaline to medium brown, but mostly olivaceous, thin- to thick-walled, smooth to verruculose, 0–3(–4)-euseptate, germinating by production of germination tubes from middle or polar cells; hila often denticle-like, somewhat protuberant, unthickened or almost so, occasionally somewhat darkened-refractive; septum ontogeny: first septum median to sub-median.

Culture characteristics:

Colonies on PDA fuscous-black, and reverse dark fuscous-black, with moderate aerial mycelium and regular, but feathery margins. Colonies normally reaching not more than 15 mm diam after 1 mo on PDA at 25 °C in the dark.

Optimal media and cultivation conditions:

PDA, MEA and CMA. Optimal growing temperature is 24–28 °C. Sometimes grows faster after cold-shock under 10 °C for 1 wk.

Distribution:

Worldwide.

Hosts:

Mainly on woody dicotyledonous plants. Twenty-four families of plants have been reported hosting venturiaceous fungi, i.e. Aceraceae, Amaryllidaceae, Asteraceae, Betulaceae, Caprifoliaceae, Cornaceae, Dipsacaceae, Ericaceae, Fagaceae, Gentianaceae, Geraniaceae, Iridaceae, Juncaginaceae, Liliaceae, Onagraceae, Oleaceae, Polygonaceae, Ranunculaceae, Rhamnaceae, Rosaceae, Rubiaceae, Salicaceae, Sapindaceae and Ulmaceae (Barr 1968, 1989, Sivanesan 1977). After studying a large number of type materials of Venturia species, many have been found to be representative of other genera (Shen et al. in prep.).

Disease symptoms:

Leaf spots, flower and fruit canker.

Notes:

Species of Venturia are widely distributed in the northern temperate region of the world, and are saprobic or parasitic on a large variety of dicotyledonous plants. Venturia comprises 198 species according to Index Fungorum. Based on the morphology of type specimens studied, the diagnostic characteristics of Venturia are as follows: Ascomata immersed, semi-immersed or superficial, scattered or gregarious, often papillate and ostiolate with setae. Hamathecium narrowly cellular, hyaline, evanescent in mature ascomata. Asci 8-spored, bitunicate, fissitunicate, broadly cylindrical to obclavate, usually lacking a pedicel. Ascospores pale olivaceous to brown, 1-septate, usually asymmetrical. Morphological discrimination of the sexual morph is limited, and the asexual morph is more informative (Sivanesan 1977). The genus is morphologically comparable to the Mycosphaerella morph of Ramularia in having bitunicate, oblong to obclavate asci with a short, thick pedicel or pedicel lacking, ellipsoidal, 1-septate ascospores which are slightly constricted at the septum. However, Venturia can be distinguished from the sexual morph of Ramularia by its setose ascomata, pale olivaceous to brown and asymmetrical ascospores. In addition, pseudoparaphyses are lacking in the sexual morph of Ramularia. Although several studies have been conducted on the phylogeny of Venturia, they mostly relied on rDNA sequences of the ITS and LSU, which proved insufficient in distinguishing some species (Crous et al. 2007, Zhang et al. 2011). More genes, especially protein coding genes are required to provide a better resolution at the species level.

References:

• Menon 1956, Nüesch 1960, Barr 1968, Sivanesan 1977 (morphology); Schubert et al. 2003 (morphology of asexual stage); Crous et al. 2007, Zhang et al. 2011, 2016 (morphology and phylogeny).
• Barr ME (1968). The Venturiaceae in North America. Canadian Journal of Botany 46: 799–864.
• Barr ME (1989). The Venturiaceae in North America: Revisions and additions. Sydowia 41: 25–40.
• Crous PW, Schubert K, Braun U, et al. (2007). Opportunistic, human-pathogenic species in the Herpotrichiellaceae are phenotypically similar to saprobic or phytopathogenic species in the Venturiaceae. Studies in Mycology 58: 185–217.
• Menon R (1956). Studies on Venturiaceae on rosaceous plants. Phytopathologische Zeitschrif 27: 117–146.
• Nüesch J (1960). Beitrag zur Kenntnis der weidenbewohnenden Venturiaceae. Phytopathologische Zeitschrif 39: 329–360.
• Schubert K, Ritschel A, Braun U (2003). A monograph of Fusicladium s. lat. (hyphomycetes). Schlechtendalia 9: 1–132.
• Sivanesan A (1977). The taxonomy and pathology of Venturia species. Lubrecht & Cramer Ltd, Vaduz, Liechtenstein.
• Zhang JQ, Dou ZhP, Zhou YP, et al. (2016). Venturia chinensis sp. nov., a new venturialean ascomycete from Khingan Mountains. Saudi Journal of Biological Sciences 23: 592–597.
• Zhang Y, Crous PW, Schoch C, et al. (2011). A molecular, morphological and ecological re-appraisal of Venturiales – a new order of Dothideomycetes. Fungal Diversity 51: 249–277.

Table 21. DNA barcodes of accepted Venturia spp.

¹CBS: Westerdijk Fungal Biodiversity Institute, Utrecht, the Netherlands; CGMCC: Chinese General Microbiological Culture Collection Center, Beijing, China; MYA: the American Type Culture Collection; OYO: Private collection. ^T indicates ex-type strain.

²ITS: internal transcribed spacers and intervening 5.8S nrDNA; tef1: partial translation elongation factor 1-alpha gene; tub2: partial beta-tubulin gene.

• Crous PW, Schubert K, Braun U, et al. (2007). Opportunistic, human-pathogenic species in the Herpotrichiellaceae are phenotypically similar to saprobic or phytopathogenic species in the Venturiaceae. Studies in Mycology 58: 185–217.
• Ibrahim M, Schlegel M, Sieber TN (2016). Venturia orni sp. nov., a species distinct from Venturia fraxini, living in the leaves of Fraxinus ornus. Mycological Progress 15: 29.
• Marin-Felix Y, Groenewald JZ, Cai, L, et al. (2017). Genera of phytopathogenic fungi: GOPHY 1. Studies in Mycology xxxx.
• Newcombe G (2003). Native Venturia inopina sp. nov., specific to Populus trichocarpa and its hybrids. Mycological Research 107: 108–116.
• Sanchez-Torres P, Hinarejos R, Tuset JJ (2009). Characterization and pathogenicity of Fusicladium eriobotryae, the fungal pathogen responsible for loquat scab. Plant Disease 93: 1151–1157.
• Shen M, Zhang JQ, Zhang Y (2017). Venturia species form sooty mold-like colonies on leaves of Salix: introducing Venturia fuliginosa sp. nov. Mycosphere 7: 1292–1300.
• Zhang JQ, Dou ZhP, Zhou YP, et al. (2016). Venturia chinensis sp. nov., a new venturialean ascomycete from Khingan Mountains. Saudi Journal of Biological Sciences 23: 592–597.
• Zhang Y, Crous PW, Schoch C, et al. (2011). A molecular, morphological and ecological re-appraisal of Venturiales – a new order of Dothideomycetes. Fungal Diversity 51: 249–277.
• Zhao P, Kakishima M, Uzuhashi S, et al.  (2012). Multigene phylogenetic analysis of inter- and intraspecific relationships in Venturia nashicola and V. pirina. European Journal of Plant Pathology 132: 245–258.