Diplodia mutila
Diplodia mutila (Fr.: Fr.) Fr., Summa Veg. Scand. 2: 417. 1849.
≡ Sphaeria mutila Fr.: Fr., Syst. Mycol. 2: 424. 1823.
≡ Physalospora mutila (Fr.: Fr.) N.E. Stevens, Mycologia28: 333. 1936.
≡ Botryosphaeria stevensii Shoemaker, Can. J. Bot. 42: 1299. 1964.
Index Fungorum number: IF 201741; Facesoffungi number: FoF05978, Fig. 1
Description:
Saprobic on stem. Sexual morph: Unknown. Asexual morph: Conidiomata 295–300 µm diam., 180–220 µm high, pycnidial, solitary to gregarious, scattered, immersed to semi-immersed, globose, unilocular, dark or pale brown, ostiolate. Ostiole 45–47 µm diam., 53–55 µm high papillate, circular, central. Conidiomata wall 25–30 µm thin, composed of thick-walled, brown cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, annellidic, indeterminate, discrete, doliiform or ampulliform, hyaline or pale brown, smooth, formed from the inner cells of the pycnidial wall. Conidia 18–21 µm × 8–10 µm (x̅ = 19.3 × 9.8 µm, n = 10), elliptical or broadly clavate, apex obtuse, base truncate, cylindrical, spherical, 0–1-septate, constricted at the septum, dark- brown, smooth-walled.
Material examined: France, on dead stem, 1 January 1882, Roumeguère C (BR5020148393807).
Fig. 1. Diplodia mutila (BR5020148393807). a, b. Herbarium material. c, d. Appearance of conidiomata on host. e. Section through conidiomata. f. Peridium. g, h. Conidiogenesis. i–o. Conidia. Scale bars: c = 4000 μm, d = 200 μm, e = 100 μm, f, g = 20 μm, h–o = 10 μm.
Importance and distribution
Diplodia seriata is the causal agent of canker, dieback, fruit rot and leaf spot diseases on economically important forest and horticultural species (Farr & Rossman 2013) while others are endophytic contributing to plant health. Diplodia produces wide range of chemicals useful for pharmaceutical and medical industry such as Sphaeropsidins A and C and (+)-epiepoformin obtained from an organic crude extract of Diplodia quercivora isolated from oak (Quercus) exhibit phytotoxic, antifungal and zootoxic activity (Andolfi et al. 2014). Diplodia tip blight characterised by brown, stunted growth affects many conifer trees, commonly the Austrian pine (Brodde et al. 2019). Diplodia seriata is the causal agent of canker, dieback, fruit rot and leaf spot diseases on economically important forest and horticultural species (Farr & Rossman 2013). Diplodia corticola causes Bot canker of oak species which causes decrease yield and reducing profits from wood and cork production (Aćimović et al. 2019).
Biochemical importance of the genus, chemical diversity or applications
Diplodia produces a wide range of chemicals. Wada and Ishida (1976) reported a pentaketide, diplodialide-D, from Diplodia pinea. Evidente et al. (2012) reported two phytotoxic dihydrofuropyran-2-ones, named afritoxinones A and B from liquid culture of Diplodia africana, the causal agent of branch dieback of Juniperus phoenicea in Italy. The author reported other phytotoxic metabolites namely (3R,4R)-4-hydroxymellein and (3R,4S)-4-hydroxymellein, episphaeropsidone, oxysporone, R-(-)-mellein, and sphaeropsidin A. Diplodia cupressi also produces episphaeropsidone and Sphaeropsidone, a phytotoxic dimedone methyl ether (Evidente et al. 2011). Sphaeropsidins B, C obtained from D. cupressi shows antibacterial activity against Xanthomonas oryzae pv. oryzae (Evidente et al. 1997). Andolfi et al. (2014) reported 20-nor-ent-pimarane termed diplopimarane, sphaeropsidins A and C and (+)-epiepoformin was isolated from an organic crude extract of Diplodia quercivora isolated from oak (Quercus). Diplopimarane has antifungal activity against plant pathogens, phytotoxic against non-host plants such as tomato cuttings and is zootoxic against Artemia salina (Andolfi et al. 2014). Other compounds such as R-(-)-mellein (Abou-Mansour et al. 2015) and tyrosol were isolated from D. mutila (Kimura & Tamura 1973). Diploquinones A and B and Vanillic acid reported from D. mutila had phytotoxic effect on grapevine leaves (Reveglia et al. 2018). Nirma et al. (2012) reported biosynthesis of D-Mannitol by Diplodia pinea. These chemicals can be used as biomarkers to identify disease development.
Though there are 715 Diplodia epithets in Index Fungorum (2022), numerous species have been transferred to other genera such as Amphisphaeria, Aplosporella, Ascochyta, Ascochytulina, Botryodiplodia, Calophoma, Chaetodiplodia, Cucurbitaria, Cyanochyta, Cytoplea, Decorospora, Diaporthe, Diplodina, Eutypella, Granulodiplodia, Heimiodiplodia, Hymenopsis, Kamatella, Lasiodiplodia, Macrophoma, Massaria, Melanops, Metadiplodia, Microbotryodiplodia, Microdiplodia, Neodeightonia, Otthia, Ovicuculispora, Paradiplodiella, Peyronellaea, Phaeobotryon, Phyllosticta, Placodiplodia, Pseudodiplodia, Schizodiplodia, Sphaerella, Sphaeropsis, Striodiplodia, Strionemadiplodia, Syndiplodia and Synnemadiplodia. Diplodia comprises 397 species known on wide range of plants such as dead branches of Abutilon indicum (Malvaceae), Acacia decurrens (Fabaceae), Acanthophyllum pungens (Caryophyllaceae), Acer saccharum (Sapindaceae), Acorus gramineus (Acoraceae), Akebia quinata (Lardizabalaceae), Alnus rubra (Betulaceae), Ampelodesmos tenacis (Poaceae), Andrachne cordifolia (Euphorbiaceae), Prunus persica (Rosaceae). Diplodia is cosmopolitan reported from Asia (Japan, Pakistan), Europe (Kazakhstan, Spain), South Africa (Western Cape Province), South Australia and The United States (Illinois, New York, Washington). The genus also needs revision as several species lack molecular data and might belong to other genera.
References
Abou-Mansour E, Débieux JL, Ramírez-Suero M, Bénard-Gellon M et al. 2015 – Phytotoxic metabolites from Neofusicoccum parvum, a pathogen of Botryosphaeria dieback of grapevine. Phytochemistry 115, 207–215.
Aćimović S, Harmon C, Bec S, Wyka S, Broders K, Doccola J. 2016 – First Report of Diplodia corticola Causing Decline of Red Oak (Quercus rubra) Trees in Maine. Plant Disease 100, 649.
Alves A, Linaldeddu BT, Deidda A, Scanu B, Phillips AJL. 2014 –The complex of Diplodia species associated with Fraxinus and some other woody hosts in Italy and Portugal. Fungal Diversity 67, 143–156.
Andolfi A, Maddau L, Basso S, Linaldeddu B et al. 2014 – Diplopimarane, a 20 -nor-ent -Pimarane Produced by the Oak Pathogen Diplodia quercivora. Journal of Natural Products 11, 2352–2360.
Ariyawansa HA, Hyde KD, Jayasiri SC, Buyck B et al. 2015 – Fungal diversity notes 111–252— taxonomic and phylogenetic contributions to fungal taxa. Fungal Diversity 75, 27–274.
Brodde L, Adamson K, Julio Camarero J, Castaño C et al. 2019 – Diplodia Tip Blight on Its Way to the North: Drivers of Disease Emergence in Northern Europe. Frontiers in Plant Science 9, 1818.
Damm U, Crous PW, Fourie PH. 2007 – Botryosphaeriaceae as potential pathogens of Prunus species in South Africa, with descriptions of Diplodia africana and Lasiodiplodia plurivora sp. nov. Mycologia 99, 664–680.
de Wet J, Wingfield MJ, Coutinho T, Wingfield BD. 2002 – Characterization of the “C” morphotype of the pine pathogen Sphaeropsis sapinea. Forest Ecology and Management 161, 181–188.
Evidente A, Maddau L, Scanu B, Andolfi A, Masi M, Motta A, Tuzi A. 2011 – Sphaeropsidones, phytotoxic dimedone methyl ethers produced by Diplodia cupressi: a structure-activity relationship study. Journal of Natural Products 74, 757–63. doi: 10.1021/np100837r.
Evidente A, Masi M, Linaldeddu BT, Franceschini A et al. 2012 – Afritoxinones A and B, dihydrofuropyran-2-ones produced by Diplodia africana the causal agent of branch dieback on Juniperus phoenicea. Phytochemistry 77, 245–50.
Evidente A, Sparapano L, Fierro O, Bruno G, Giordano F, Motta A. 1997 – Sphaeropsidins B and C, phytotoxic pimarane diterpenes from Sphaeropsis sapinea f. sp. Cupressi and Diplodia mutila. Phytochemistry 45, 705–713.
Farr DF, Rossman AY. 2013 – Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.
González-Domínguez E, Alves A, León M, Armengol J. 2017 – Characterization of Botryosphaeriaceae species associated with diseased loquat (Eriobotrya japonica) in Spain. The Plant Pathology Journal 66, 77–89.
Hyde KD, Nilsson RH, Alias SA, Ariyawansa HA et al. 2014 – One stop shop: backbones trees for important phytopathogenic genera: I. Fungal Diversity 67, 21–125.
Kimura Y, Tamura S. 1973 – Isolation of L-b-phenyllactic acid and tyrosol as plant growth regulators from Gloeosporium laeticolor. Agricultural and Biological Chemistry 37, 2925–2925.
Nirma C, Rodrigues A, Basset C, Chevolot L et al. 2012 – Larvicidal Activity of Isoflavonoids from Muellera Frutescens Extracts Against Aedes Aegypti. Natural product communications 7, 1319–1322.
Osorio JA, Crous CJ, de Beer ZW, Wingfield MJ, Roux J. 2017 – Endophytic Botryosphaeriaceae, including five new species, associated with mangrove trees in South Africa. Fungal biology, 121, 361–393.
Phillips AJ, Alves A, Pennycook SR, Johnston PR, Ramaley A, Akulov A, Crous PW. 2008 –Resolving the phylogenetic and taxonomic status of dark-spored teleomorph genera in the Botryosphaeriaceae. Persoonia 21, 29–55.
Phillips AJL, Alves A, Abdollahzadeh J, Slippers B, Wingfield MJ, Groenewald JZ, Crous PW. 2013 – The Botryosphaeriaceae: genera and species known from culture. Studies in Mycology 76, 51–167.
Reveglia P, Savocchia S, Billones-Baaijens R, Masi M, Cimmino A, Evidente A. 2018 – Diploquinones A and B, Two New Phytotoxic Tetrasubstituted 1,4-Naphthoquinones from Diplodia mutila, a Causal Agent of Grapevine Trunk Disease. Journal of Agricultural and Food Chemistry 66, 11968–11973.
Tennakoon DS, Kuo C, Maharachchikumbura SSN, Thambugala KM et al. 2021 – Taxonomic and phylogenetic contributions to Celtis formosana, Ficus ampelas, F. septica, Macaranga tanarius and Morus australis leaf litter inhabiting microfungi. Fungal Diversity 108, 1– 215.
Wada K, Ishida T. 1976 – A new pentaketide, diplodialide-D, from Diplodia pinea. Journal of The Chemical Society, Chemical Communications 340–341.
Yang T, Groenewald JZ, Cheewangkoon R, Jami F, Abdollahzadeh J, Lombard L, Crous PW. 2017 – Families, genera and species of Botryosphaeriales. Fungal Biology 121, 322–346.
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