Fusarium chuoi R. Hill, Gaya, D.T. Vu, Sand.-Den. & Crous, 2021

Crous, P. W., Osieck, E. R., Jurjevi, Ž, Boers, J., Van Iperen, A. L., Starink-Willemse, M., Dima, B., Balashov, S., Bulgakov, T. S., Johnston, P. R., Morozova, O. V., Pinruan, U., Sommai, S., Alvarado, P., Decock, C. A., Lebel, T., McMullan-Fisher, S., Moreno, G., Shivas, R. G., Zhao, L., Abdollahzadeh, J., Abrinbana, M., Ageev, D. V., Akhmetova, G., Alexandrova, A. V., Altés, A., Amaral, A. G. G., Angelini, C., Antonín, V., Arenas, F., Asselman, P., Badali, F., Baghela, A., Bañares, A., Barreto, R. W., Baseia, I. G., Bellanger, J. - M., Berraf-Tebbal, A., Biketova, A. Yu., Bukharova, N. V., Burgess, T. I., Cabero, J., Câmara, M. P. S., Cano-Lira, J. F., Ceryngier, P., Chávez, R., Cowan, D. A., de Lima, A. F., Oliveira, R. L., Denman, S., Dang, Q. N., Dovana, F., Duarte, I. G., Eichmeier, A., Erhard, A., Esteve-Raventós, F., Fellin, A., Ferisin, G., Ferreira, R. J., Ferrer, A., Finy, P., Gaya, E., Geering, A. D. W., Gil-Durán, C., Glässnerová, K., Glushakova, A. M., Gramaje, D., Guard, F. E., Guarnizo, A. L., Haelewaters, D., Halling, R. E., Hill, R., Hirooka, Y., Hubka, V., Iliushin, V. A., Ivanova, D. D., Ivanushkina, N. E., Jangsantear, P., Justo, A., Kachalkin, A. V., Kato, S., Khamsuntorn, P., Kirtsideli, I. Y., Knapp, D. G., Kochkina, G. A., Koukol, O., Kovács, G. M., Kruse, J., Kumar, T. K. A., Kušan, I., Læssøe, T., Larsson, E., Lebeuf, R., Levicán, G., Loizides, M., Marinho, P., Luangsa-ard, J. J., Lukina, E. G., Magaña-Dueñas, V., Maggs-Kölling, G., Malysheva, E. F., Malysheva, V. F., Martín, B., Martín, M. P., Matočec, N., McTaggart, A. R., Mehrabi-Koushki, M., Mešić, A., Miller, A. N., Mironova, P., Moreau, P. - A., Morte, A., Müller, K., Nagy, L. G., Nanu, S., Navarro-Ródenas, A., Nel, W. J., Nguyen, T. H., Nóbrega, T. F., Noordeloos, M. E., Olariaga, I., Overton, B. E., Ozerskaya, S. M., Palani, P., Pancorbo, F., Papp, V., Pawłowska, J., Pham, T. Q., Phosri, C., Popov, E. S., Portugal, A., Pošta, A., Reschke, K., Reul, M., Ricci, G. M., Rodríguez, A., Romanowski, J., Ruchikachorn, N., Saar, I., Safi, A., Sakolrak, B., Salzmann, F., Sandoval-Denis, M., Sangwichein, E., Sanhueza, L., Sato, T., Sastoque, A., Senn-Irlet, B., Shibata, A., Siepe, K., Somrithipol, S., Spetik, M., Sridhar, P., Stchigel, A. M., Stuskova, K., Suwannasai, N., Tan, Y. P., Thangavel, R., Tiago, I., Tiwari, S., Tkalčec, Z., Tomashevskaya, M. A., Tonegawa, C., Tran, H. X., Tran, N. T., Trovão, J., Trubitsyn, V. E., Van Wyk, J., Vieira, W. A. S., Vila, J., Visagie, C. M., Vizzini, A., Volobuev, S. V., Vu, D. T., Wangsawat, N., Yaguchi, T., Ercole, E., Ferreira, B. W., de Souza, A. P., Vieira, B. S. & Groenewald, J. Z., 2021, Fusarium chuoi R. Hill, Gaya, D. T. Vu, Sand. - Den. & Crous, R. Hill, Gaya, D. T. Vu, Sand. - Den. & Crous sp. nov., Fungal Planet 47 (1), pp. 310-311 : 311

Fusarium chuoi R. Hill, Gaya, D.T. Vu, Sand.-Den. & Crous , sp. nov.

Etymology. From chuối, Vietnamese vernacular name for Musa spp. , from which the ex-type strain was isolated.

Classification — Nectriaceae , Hypocreales , Sordariomycetes.

On SNA and CLA, sporulation abundant from aerial conidiophores and sporodochia. Aerial conidiophores erect or prostrate, copiously branching laterally and sympodially, giving rise to macro-, and rarely, microconidia; aerial conidiogenous cells mono- and polyphialidic, subulate to subcylindrical, smooth- and thin-walled, proliferating sympodially, 6.5–40.5 × 2.5–4 µm, with apical flared collarette and periclinal thickening; aerial conidia of two types: microconidia often produced on prostrate conidiophores, rarely on aerial mycelium, aggregating in false heads, ellipsoidal, subcylindrical to slightly falcate, 0 –1-septate, 8–15 × 2–29.5 µm; macroconidia fusiform to falcate, straight to apically dorsiventrally curved, apex curved to pointed, base obtuse to papillate, 1–3-septate, smooth- and thin-walled; 1-septate conidia: (14–)18–27.5(–29.5) × (2.5–)3–4 μm (av. 22.8 × 3.2 μm); 2-septate conidia: 26–28.5 × 3–4 μm (av. 27.4 × 3.6 μm); 3-septate conidia: (28–)31.5–43(–50.5) × 3–4 μm (av. 37.3 × 3.5 μm). Sporodochia saffron, luteous to ochreous coloured ( Rayner 1970), formed abundantly on the agar surface and carnation leaves under nuv. Conidiophores in sporodochia, densely and irregularly branched, bearing apical whorls of 2 – 4 monophialides; sporodochial monophialides subcylindrical, 10–26 × 2.5–4.5 µm, smooth- and thin-walled, with a distinct apical collarette. Sporodochial conidia (macroconidia) falcate, almost straight to gently curved, tapering at both ends, apex curved to blunt, base poorly- to well-developed foot-shaped, 1–6-septate, hyaline, smooth- and thin-walled; 1-septate conidia: (14.5–)15–20.5(–24) × 3–4.5 µm (av. 17.9 × 3.9 µm); 2-septate conidia: 21.5–32 × 3–4.5 µm (av. 26.4 × 3.5 µm); 3-septate conidia: (33–)43–61(–71.5) × (3–)4–5 µm (av. 51.8 × 4.2 µm); 4-septate conidia: (50.5–)55–69(–74.5) × 3.5–5 µm (av. 62.3 × 4.2 µm); 5-septate conidia: 54 × 4.5 µm (rare); 6-septate conidia: (49.5–)56.5–71(–73) × (3.5–)4–4.5(–5) µm (av. 63.8 × 4.3 µm). Chlamydospores not observed.

Culture characteristics — Colonies on potato dextrose agar (PDA) and oatmeal agar (OA) growing in the dark at 24 °C covering and entire 9 cm Petri dish in 7 d. Colony surface peach to vinaceous, flat, velvety to felty with abundant floccose aerial mycelium forming concentric rings; colony margins undulate. Reverse flesh to salmon with diffuse coral to brick pigment throughout the medium.

Typus. VIETNAM, Hà Tĩnh Province, HƯƠng SƠn District,SƠn Kim commune , N18°25'37.38" E105°12'53.95", inside seed of Musa itinerans (Musaceae) , 9 Nov. 2014, D.M. Thu, L.T. Phong & T.T. Duong, isol. R. Hill (holotype CBS H-24901 ,culture ex-type CBS 148464 ; ITS, LSU, cmdA, rpb1, rpb2, tef1 and tub2 sequences GenBank OK586454 , OK586452 , OK626304 , OK626306 , OK626302 , OK626308 and OK626310 , MycoBank MB 841865).

Colour illustrations. Flowers, fruits, leaves and seeds of Musa itinerans (background photo by D.T. Vu); from top to bottom and left to right: colony on PDA after 14 d at 24 °C in darkness (left = obverse,right = reverse), sporodochia formed on CLA,aerial conidiophore,aerial conidiogenous cells,aerial conidia, sporodochial conidia. Scale bars: black = 20 µm, white = 10 µm.

Additional material examined. VIETNAM, Nghệ An Province, Con Cuông District, Châu Khê commune, N19°1'48.73" E104°43'31.97", inside seed of M. itinerans , 18 Nov. 2014, L.T. Phong, V.V. Tung & T.T. Duong, isol. R. Hill (culture CBS 148465 ; ITS, LSU, cmdA, rpb1, rpb2, tef1 and tub2 sequences GenBank OK586455 , OK586453 , OK626305 , OK626307 , OK626303 , OK626309 and OK626311 ) .

Notes — Fusarium chuoi resides in the Asian clade of the Fusarium fujikuroi species complex ( FFSC: O’Donnell et al. 1998, Yilmaz et al. 2021, Crous et al. 2021b). Based on nucleotide searches using the Fusarium Pairwise ID engine on the Fusarioid-ID database (www.fusarium.org, Crous et al. 2021) the closest hit using the ITS sequence was Fusarium siculi (strain CBS 142422; identities = 449/450 (99 %), no gaps). The closest hit using the LSU sequence was F. siculi (strain CBS 142422; identities = 804/805 (99 %), no gaps). Closest hit using the cmdA sequence was Fusarium fractiflexum (strain NRRL 28852; identities = 426/434 (98 %), no gaps). Closest hit using the rpb1 sequence was F. fujikuroi (strain NRRL 13566; identities = 687/702 (98 %), no gaps). Closest hit using the rpb2 sequence was Fusarium globosum (strain CBS 428.97; identities = 856/867 (98 %), no gaps). Closest hit using the tef1 sequence was F. fractiflexum (strain NRRL 28852; identities = 619/643 (96 %), 2 gaps (0.3 %)). The phylogenetic results, however, showed that F. chuoi is not directly related to any of the previously described species of FFSC (see Suppl. material FP1353), clustering as the second basal-most species of that clade after F. sacchari .

Asian Fusarium spp. in the FFSC are characterised by mono-and polyphialides producing oval to ellipsoid, rarely pyriform to globose (i.e., F. annulatum , F. fujikuroi and F. globosum ) microconidia organized in chains or false heads; 3–5-septate sporodochial conidia and lacking chlamydospores. The elaborate, profusely branched aerial conidiophores of F. chuoi are comparable to those of F. concentricum , F. lumajangense , F. mangiferae and F. sacchari , all the latter species producing oval, ellipsoidal to allantoid microconidia on false heads.Aerial conidiophores of F. chuoi, however, mostly produce macroconidia, while microconidia grouped on false heads are restricted to short, mostly unbranched and prostrate conidiophores formed on the surface on the culture media.

Several Asian species of the FFSC have been reported from Musa spp. i.e., F. annulatum , F. concentricum , F. fujikuroi , F. lumajangense and F. sacchari ( Leslie & Summerell 2006, Maryani et al. 2019, Farr & Rossman 2021). The two strains representing F. chuoi were isolated as endophytes from asymptomatic seeds of wild banana ( Musa itinerans ), which had been collected predispersal and stored in the Millennium Seed Bank for ~2.5 years at -20 °C prior to isolation.

Supplementary material

FP1353 Phylogenetic tree.

Figures

Colour illustrations. Flowers, fruits, leaves and seeds of Musa itinerans (background photo by D.T. Vu); from top to bottom and left to right: colony on PDA after 14 d at 24 °C in darkness (left = obverse,right = reverse), sporodochia formed on CLA,aerial conidiophore,aerial conidiogenous cells,aerial conidia, sporodochial conidia. Scale bars: black = 20 µm, white = 10 µm.