Pseudocercospora sp. B

Bakhshi, Mounes, Arzanlou, Mahdi, Babai-Ahari, Asadollah, Groenewald, Johannes Z. & Crous, Pedro W., 2014, Multi-gene analysis of Pseudocercospora spp. from Iran, Phytotaxa 184 (5), pp. 245-264 : 258-260

Pseudocercospora sp. B ( Fig. 9 )

Description in planta:— Leaf spots distinct, scattered over leaf surface, amphigenous, irregular to subcircular, 2–7 mm diam., pale brown in centre, surrounded by a slightly raised dark brown border. Mycelium internal. Caespituli predominantly epiphyllous, in dense fascicles, olivaceous-brown on leaves. Stromata well-developed, arising through stomata, or erumpent through the cuticle, globular, sub-immersed, 20–45 μm diam. Conidiophores medium brown, becoming paler toward the apex, arranged in dense fascicles, smooth to granular, 0–3-septate, unbranched, straight to curved, subcylindrical, uniform in width, apex rounded to subtruncate, (10–)20–26(–45) ×(2.5–)3–4 μm. Conidiogenous cells terminal, or conidiophores reduced to conidiogenous cells, pale brown, smooth, 10–25 × 2.5–3.5 μm, proliferating sympodially, c onidiogenous loci neither thickened nor darkened, 1–2.5 μm diam. Conidia solitary, subhyaline to pale brown, guttulate, subcylindrical to obclavate, somewhat constricted at septa, apex obtuse to subobtuse, base truncate to obconically truncate, straight to gently curved, 3–15-septate, (25–)48–65(–130) × 2–4 μm; hila not thickened nor darkened or refractive, 1–2.5 μm diam.

Cultural characteristics:— Colonies on MEA reaching 28 mm diam. after 20 days at 25 ºC in the dark; surface folded, erumpent with moderate aerial mycelium and irregular lobate margins; surface honey in centre, dark brown in outer region; reverse dark brown.

Material examined:— IRAN. Mazandaran Province: Ramsar, on Diospyros lotus L. ( Ebenaceae ), October 2012, M. Bakhshi ( CCTU 1206 = CBS 136114). Mazandaran Province: Ramsar, Kotra, on D. lotus , October 2012, M. Bakhshi ( CCTU 1191). Guilan Province: Talesh, Kishunben, on Diospyros lotus , October 2012, M. Bakhshi ( CCTU 1066).

Notes:— Pseudocercospora sp. B cannot be distinguished from several other species solely based on the ITS phylogeny. In the ACT phylogeny, it clusters in a clade with isolates of P. basiramifera and P. rubi . In the TEF 1-α phylogeny, it resides in a well-supported clade sister to a clade including P. cotoneastri and P. elaeocarpi . In the combined gene tree, it forms a distinct clade sister to the clade including P. cotoneastri and P. elaeocarpi . Ecologically, Pseudocercospora sp. B appears to be specific to Diospyros lotus as the Diospyros kaki trees growing next to the Diospyros lotus trees, which remained uninfected by this fungus. Thus far, two species of Pseudocercospora , namely P. kaki and P. diospyri -morrisianae have been reported from Diospyros ( Crous & Braun 2003) . Pseudocercospora sp. B is morphologically different from P. diospyri -morrisianae ( Kim & Shin 1998) based on its dense conidiophore fascicles and somewhat longer and narrower conidia . There are three Pseudocercospora species reported on other Diospyros species including P. diospyri -erianthae (on Diospyros eriantha and D. latifolia ), P. diospyricola (on Diospyros sp. ) and P. diospyri - lycioides (on D. lycioides var. lycioides ) ( Crous & Braun 2003). Morphologically Pseudocercospora sp. B differs from P. diospyri - eriantha by its medium brown conidiophores that become paler toward their apices, and 3–15- septate conidia with obtuse to subobtuse apices (versus 3–9-septate in P. diospyri - eriantha ) ( Crous & Braun 1995). Pseudocercospora sp. B also differs from P. diospyri - lycioides in having longer and wider conidiophores and wider conidia , and from P. diospyricola in lacking superficial mycelium and secondary conidiophores ( Crous & Braun 1995). Pseudocercospora sp. B agrees with the description of P. kaki given by Guo & Hsieh (1995: 92-93), based on Chinese material on Diospyros kaki and D. lotus ( U. Braun, pers. comm.). Unfortunately there is presently no DNA sequence data of P. kaki from Taiwan, which is the island from where it was originally described. The Iranian material studied here clusters quite distinct from the Japanese ( P. kaki ) and Korean ( P. cf. kaki ) material ( Fig. 2 ), but Pseudocercospora sp. B can only be resolved once fresh material from Taiwan has been subjected to DNA sequence analysis.

Pseudocercospora vitis (Lév.) Speg., Anales Mus. Nac. Hist. Nat. Buenos Aires, Ser. 3, 20: 438. 1910 ( Fig. 10 ) Additional synonyms in Crous & Braun (2003)

Description in planta:— Leaf spots distinct, amphigenous, circular to subcircular, 2–15 mm diam., with black circle in the centre arounded by brown circle and black border (appearing as eye-spot). Mycelium internal. Caespituli epiphyllous. Stromata well-developed, substomatal to intraepidermal, semi-immersed to superficial, 35–70 μm diam. Conidiophores synnematous, arising from stromata, through stomata or erumpent through the cuticle, brown, smooth, unbranched, straight to curved, subcylindrical, regular in wide, (95–)155–195(–245) × 4–5.5 μm. Conidiogenous cells terminal, brown, smooth, proliferating sympodially, (12–)15–20(–30) × 3.5–5 μm, loci neither thickened nor darkened. Conidia solitary, brown, obclavate, apex subobtuse, base obconically truncate, straight to gently curved, 2–7-septate, (28–)40–55(–75) × 3–4.5 μm; hila neither thickened nor darkened or refractive, 1–2.5 μm diam.

Habitat/Distribution:— Known to inhabit Ampelopsis aconitifolia , A. arborea , A. cordata , A. brevipedunculata , Cissus rhodesiae , Cissus sp. , Vitis amurensis, V. california , V. cordifolia , V. davidii , V. labrusca , V. palmate , V. rotundifolia , V. rupestris , V. vinifera , Vitis sp., worldwide including Australia, Austria, Bangladesh, Barbados, Brazil, Bulgaria, China, Colombia, Cyprus, Denmark, Egypt, France, Georgia, Germany, Guatemala, India, Indonesia, Iran, Italy, Japan, Korea, Lebanon, Libya, Madagascar, Malaysia, Malta, Mauritius, Mexico, Moldova, Mozambique, Myanmar, Nepal, New Caledonia, New Zealand, Oman, Pakistan, Panama, Peru, Poland, Portugal, Russia (Asia and European part), Saudi Arabia, Slovakia, Slovenia, Somalia, South Africa, Sri Lanka, Swaziland, Tadzhikistan, Taiwan, Thailand, Trinidad and Tobago, Ukraine, USA (AL, FL, LA, NC, WI), Uzbekistan, Venezuela, former Yugoslavia, Zimbabwe ( Crous & Braun 2003, Farr & Rossman 2014).

Material examined:— IRAN. Guilan Province: Sowme’eh Sara, Bahambar, on Vitis sp. ( Vitaceae ), August 2012, M . Bakhshi ( CCTU 1076 ) .

Notes:— Pseudocercospora vitis is the type species of the genus Pseudocercospora . This species always forms a monophyletic clade in all of the individual gene trees including LSU, ITS, ACT and TEF1 -α. In the combined gene tree ( ITS, ACT and TEF1 -α), it clusters in a well-supported basal clade .

Figures

FIGURE 2. A Bayesian inference phylogenetic tree of 59 isolates of Pseudocercospora. The tree was built using concatenated sequences of the ITS, ACT and TEF1-α loci, each with a separate model of DNA evolution. Species clades from Iran are indicated in green coloured blocks and species names in black text. Culture accession numbers are listed along with host plant (orange text) and place of origin (dark blue text). The tree was rooted to Passalora eucalypti (CBS 111318). Bayesian posterior probabilities ≥ 0.95 are indicated with colourcoded branches and scale bar indicates number of expected changes per site.

FIGURE 9. Pseudocercospora sp. B. a–b. Leaf spots. c–d. Fasciculate conidiophores. e–g. Conidia. Scale bars = 10 µm.

FIGURE 10. Pseudocercospora vitis. a. Leaf spots on upper and lower leaf surface. b, c. Synnematal fascicles with conidiophores and conidiogenous cells. d–g. Conidia. Scale bars = 10 µm.