Verticillium alfalfae

Verticillium alfalfae

MycoBank: MB563552

Etymology: Medicago sativa (‘alfalfa’), the only currently known host of this species.

Latin diagnosis.

Verticillio nonalfalfae morphologia simile, sed characteribus sequentiarum nucleidearum distinguendum. Actin positione 21 (T), 72 (G), 78 (T), 459 (A), 462 (A); Elongation factor 1-alpha positione 149 (G), 157 (G), 175 (G), 225 (A), 265 (T), 266 (A), 271 (A), 280 (C), 304 (T), 346 (C), 428 (T), 429 (T), 441 (G), 465 (T), 469 (C), 474 (T), 591 (C), 596 (T), 600 (C), 624 (T); Glyceraldehyde-3-phosphate dehydrogenase positione 173 (A), 324 (C); Tryptophan synthase positione 87 (A), 161 (T), 169 (C), 246 (T), 273 (T), 315 (T), 583 (T), 601 (C).

Description.

Colonies on PDA after two weeks 3.5–4.5 cm diam, white at first (Figures 5a, 5b), later darkening due to the formation of resting mycelium immersed in the agar. Aerial mycelium generally abundant, floccose to pruinose, hyphae smooth-walled, 2–3 µm wide. Conidiophores erect or slanted, generally determinate (Figure 5c), branched or unbranched, formed disjointedly throughout the colonies, hyaline, base brown-pigmented at times, enlarged to up to 11 µm at times, 70–570 µm in length, 4.5–6.5 µm wide, narrowing towards the apex to 2–2.5 µm, transversely septate, septa spaced more narrowly towards the apex (Figure 5c). Conidiogenous cells are phialides (Figure 5d), arranged in 1–4 (–6) whorls along conidiophores (Figure 5c). Whorls spaced 30–130 µm apart, closer towards the apex, consisting of (1–) 2–5 (–6) phialides, arising below transverse septum (Figures 5c, 5d). Apical whorls consisting of one apical and one to several lateral phialides (Figures 5c, 5d). Phialides subulate, tapering from 2–3 µm at the base to 1–2.5 µm at the tip, terminal phialides 40–60 µm long, lateral phialides 20–40 µm long (Figure 5d). Conidia hyaline, smooth-walled, cylindrical with rounded apices to oval (Figure 5e), allantoid at times, (4.5–) 6.0 µm±1.0 µm (–11.0)×(2.5–) 3.0 µm±0.5 µm (–4.0) (l/w = (1.4–) 1.9±0.3 (–2.9), n = 68), accumulating at the tip of the phialides (Figure 5c). Resting mycelium present (Figures 5f, 5g, 5h), consisting of brown-pigmented hyphae, up to 9 µm wide, thick-walled (Figures 5f, 5g), straight or curved, solitary or aggregated (Figure 5g), torulose at times.

Types.

Holotype: Dried culture of V. alfalfae strain PD489 (USA; alfalfa) deposited at UC (UC 1953895), an ex-holotype culture at CBS (CBS 130603) and NRRL (NRRL 54790).

Specimens examined.

The description was based on V. alfalfae strains PD338 (USA: PA; alfalfa), PD353 (USA: PA; alfalfa), PD489 (USA; alfalfa), PD620 (Canada; alfalfa), PD681 (USA; alfalfa), PD682 and PD683 (Japan: Hokkaidou; alfalfa) (Table S1).

Distribution and host range.

Currently known from Canada, Japan and the USA (PA), only from alfalfa.

Commentary.

Verticillium alfalfae is morphologically indistinguishable from V. nonalfalfae.