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Colletotrichum: complex species or species ... - CBS - KNAW

Colletotrichum: complex species or species ... - CBS - KNAW

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Damm et al.Fig. 7. <strong>Colletotrichum</strong> cosmi (from ex-holotype strain <strong>CBS</strong> 853.73). A–B. Conidiomata. C–H. Conidioph<strong>or</strong>es. I–N. Appress<strong>or</strong>ia. O–P. Conidia. A, C–E, O. from Anthriscus stem.B, F–N, P. from SNA. A–B. DM, C–P. DIC, Scale bars: A = 200 µm, B = 100 µm, C = 10 µm. Scale bar of C applies to C–P.4.0 ± 0.3 µm, L/W ratio = 3.8.Culture characteristics: Colonies on SNA flat with entire margin,hyaline, buff to pale honey, on filter paper partly pale olivaceousgrey, the medium, filter paper and Anthriscus stem partly coveredwith floccose-felty whitish to pale olivaceous grey aerial myceliumand <strong>or</strong>ange acervuli, reverse of filter paper partly pale cinnamon,pale olivaceous grey to olivaceous grey; growth rate 23–24 mmin 7 d (33.5–34 mm in 10 d). Colonies on OA flat with entiremargin; surface entirely covered with thin floccose-felty white topale olivaceous grey aerial mycelium and <strong>or</strong>ange acervuli, reversevinaceous buff, purplish grey to fuscous black; growth rate 23–25mm in 7 d (33.5–37.5 mm in 10 d). Conidia in mass <strong>or</strong>ange.Material examined: Netherlands, Wageningen, from seed of Cosmos sp., collectiondate and collect<strong>or</strong> unknown (deposited in <strong>CBS</strong> collection in Nov. 1973 by G.H.Boerema), (<strong>CBS</strong> H-20794 holotype, culture ex-type <strong>CBS</strong> 853.73 = PD 73/856).Notes: Kwon et al. (1999) rep<strong>or</strong>t C. acutatum (s. lat.) to cause sunkenbrownish spots on stems, as well as symptoms on leaves, flowersand fl<strong>or</strong>al axes of Cosmos bipinnatus in K<strong>or</strong>ea. M<strong>or</strong>phologicalcharacters (conidia, appress<strong>or</strong>ia) are similar to those of strain <strong>CBS</strong>853.73, except f<strong>or</strong> setae, which our strain did not develop in ourstandard culture conditions. It is theref<strong>or</strong>e possible that the collectionfrom K<strong>or</strong>ea represents C. cosmi. <strong>Colletotrichum</strong> acutatum (s. lat.) isalso known as an anthracnose pathogen of flowers and flower budsof Cosmos bipinnatus in Japan (Yaguchi et al. 1996). The shape ofconidia and appress<strong>or</strong>ia of the Japanese fungus are similar to ourstrain, but the conidia are smaller, measuring 11–14 × 2.8–3.5 µm.Two other <strong>species</strong> are rep<strong>or</strong>ted from Cosmos bipinnatus in India, C.truncatum (as C. capsici) associated with seeds and causing seedand seedling rot (Srivastava et al. 1981) and C. gloeosp<strong>or</strong>ioidesassociated with leaves (Kumari et al. 1981). When strain <strong>CBS</strong>853.73 was first accessed into <strong>CBS</strong>, von Arx identified it as C.gloeosp<strong>or</strong>ioides, but with the remark “deviating by longer, slenderconidia”. Molecular data do not supp<strong>or</strong>t this identification; the strainbelongs to the C. acutatum <strong>complex</strong>, but it is possible that rep<strong>or</strong>tsof C. gloeosp<strong>or</strong>ioides refer to this <strong>species</strong>.<strong>Colletotrichum</strong> cosmi is part of clade 2. It can be separatedfrom other <strong>species</strong> by all gene sequences, but mostly with only 1bp divergence. There are m<strong>or</strong>e sequence divergences in GAPDHand HIS3; however, with these genes individually, the <strong>species</strong> sitswithin the very variable C. nymphaeae clade. The closest matchin a blastn search with the TUB2 sequence of strain <strong>CBS</strong> 853.73(with 99 % identity, 4 bp differences) was GU246633 from isolateR14 from Capsicum annuum from South K<strong>or</strong>ea (Sang et al. 2011),while the closest match with the GAPDH sequence covering ±the full length sequence (with 98 % identity, 4 bp differences) wasHQ846724 from isolate OBP6 from an unknown plant, probablyfrom India (P. Chowdappa, C.S. Chethana, S. Madhura, unpubl.data). We do not consider that these data in isolation are sufficientevidence to identify these sequences as <strong>or</strong>iginating from C. cosmi.There are 22 sequences in GenBank that match the ITS sequenceof strain <strong>CBS</strong> 853.73 with 99 % identity, all with 2 bp differences.62

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