Verticillium dahliae

General information about Verticillium dahliae is provided below. Included are a morphological description, comments about morphologically similar species and phylogenetic affiliation. The data is from Inderbitzin et al. (2011) where additional information can be found. Host range data is from Inderbitzin and Subbarao (2014).

Species Description

Colonies on PDA after two weeks 4–6 cm diam, white at first, later darkening due to the formation of microsclerotia (Figures 6a, 6b). Aerial mycelium generally abundant, floccose, at times sparse and pruinose, or appressed to the agar and appearing water-soaked. Aerial hyphae smooth-walled, (1.5–) 2–4 µm wide, at times containing inflated cells up to 9 µm wide (Figure 6c). Conidiophores erect or slanted, generally determinate (Figure 6d), branched or unbranched (Figure 6e), formed disjointedly throughout the colonies, hyaline, 80–800 µm in length, 3–4 µm wide, narrowing towards the apex, transversely septate, septa spaced more narrowly towards the apex. Conidiogenous cells are phialides (Figure 6f), arranged in (1–) 2–3 (–10) whorls along conidiophores (Figures 6d, 6e), arising below transverse septum (Figure 6f). Whorls spaced 50–100 µm apart, closer towards the apex, consisting of (1–) 2–4 (–6) phialides (Figures 6d, 6e). Apical whorls consisting of one apical and one to several lateral phialides (Figure 6d). At times solitary phialides are formed laterally from vegetative hyphae (Figure 6g). Phialides subulate, tapering from 2–3 µm at the base to 1–2 µm at the tip, terminal phialides 40–60 µm long, lateral phialides 25–50 µm long (Figures 6d, 6e, 6f, 6g). Conidia hyaline, smooth-walled, non-septate, cylindrical with rounded apices to oval (Figure 6h), allantoid or tapering at times, (3.5–) 6.5 µm±1.5 µm (–13.5)×(2.0–) 3.0 µm±0.5 µm (–4.5) (l/w = (1.4–) 2.2±0.3 (–3.4), n = 80), accumulating at the tip of the phialides (Figures 6d, 6e). Microsclerotia immersed in agar, regularly or irregularly distributed throughout the colonies, composed of rounded, brown-pigmented cells up to 13 µm diam, solitary microsclerotia rounded to elongate or irregular in shape, 25–100 µm diam, aggregates of microsclerotia up to 200 µm diam (Figures 6i, 6j, 6k). At times short, brown-pigmented hyphae attached to microsclerotia present (Figure 6k).

Morphologically similar species

Verticillium dahliae resembles V. longisporum, but has smaller conidia.

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Figure 6. Morphological features of Verticillium dahliae strain PD322 (ex-epitype) unless otherwise noted.

6a. Colony after 14 days on PDA, frontal view. 6b. Colony after 14 days on PDA, reverse view. 6c. Inflated cells present in mycelium after 28 days on PDA. 6d. Conidiophore after 15 days on WA-p. 6e. Branched conidiophore after 12 days on WA-p. 6f. Whorl phialide after 25 days on WA-p. 6g. Solitary phialide after 14 days on PDA. 6h. Conidia after 9 days on PDA. 6i. Microsclerotia after 12 days on WA-p. 6j. Microsclerotia of the V. dahliae holotype material from stem of Dahlia sp. 6k. Short brown-pigmented hypha composed of torulose cells attached to microsclerotium after 49 days on PDA. Scale bar: 6a, 6b = 2 cm; 6c, 6f–6k = 20 µm; 6d, 6e = 50 µm. Imaging method: 6a, 6b = DS; 6c, 6f–6h = DIC; 6d, 6e, 6i, 6k = BF; 6j = PC.

doi:10.1371/journal.pone.0028341.g006

Phylogenetic position

Verticillium dahliae belongs to the group of Verticillium that does not produce yellow-pigmented hyphae (group Flavnonexudans), and is one of the parents of V. longisporum that is a diploid hybrid. For a phylogenetic tree, see Figure 1 in Inderbitzin et al. (2011).

Host range and geographic distribution

These are inferred from GenBank ITS records, and most likely underestimate the current host range and geographic distribution of V. dahliae.

SubstratesGeographic distribution# plant hosts / # countries
African eggplant (Solanum aethiopicum), Alectryon (Alectryon sp.), Almond (Prunus dulcis), American black nightshade (Solanum nigrum), Anaheim pepper (Capsicum annuum), Apricot (Prunus armeniaca), Artichoke (Cynara scolymus), Aztec marigold (Tagetes erecta), Bell pepper (Capsicum annuum), Black raspberry (Rubus sp.), Black-eyed Susan (Rudbeckia hirta), Brassica oleracea var. capitatac, Brassica oleracea var. italicaC, Broccoli (Brassica oleracea var. botrytis), Cabbage (Brassica oleracea), Celandine (Chelidonium majus), Chamomile (Matricaria chamomilla), Chicory (Cichorium intybus),
Chili pepper (Capsicum annuum), Chinese cabbage (Brassica oleracea), Coleus (Coleus verschaffeltii), Coneflower (Echinacea purpurea), Cosmos (Cosmos bipinnatus), Cota palaestina, Cotton (Gossypium hirsutum), Cyprus- vetch (Lathyrus ochrus), Eggplant (Solanum melongena), European smoketree (Cotinus coggygria), European yellow lupine (Lupinus luteus), Figmarigold (Lampranthus spp.), Flax (Linum usitatissimum), French marigold (Tagetes patula), Grapevine (Vitis vinifera), Green ash (Fraxinus pennsylvanica), Horse- radish (Armoracia rusticana), Icelandic poppy (Papaver nudicaule), Italian cockleburr (Xanthium italicum), Jalapeno (Capsicum annuum), Japanese maple (Acer palmatum), Lactuca sativa var. longifolia, Lambsquarters (Cheno- podium album), Lenspod whitetop (Cardaria draba), Lettuce (Lactuca sativa), Lupine (Lupinus polyphyllus), Nestegis sp., New Zealand spinach (Tetragonia tetragonioides), Norway maple (Acer platanoides), Oilseed rape (Brassica napus sp. oleifera), Okra (Abelmoschus esculentus), Old-man-in-the-Spring (Senecio vulgaris), Olive (Olea europaea), Opium poppy (Papaver somniferum), Orange coneflower (Rudbeckia fulgida), Paprika (Capsicum annuum), Peach (Prunus persica), Peanut (Arachis hypogaea), Peppermint (Mentha x piperita), Pistachio (Pistacia vera), Potato (Solanum tuberosum), Pumpkin (Cucurbita pepo), Purple coneflower (Echinacea purpurea), Radish (Raphanus raphanistrum), Rose (Rosa sp.), Scentless false mayweed (Tripleurospermum perforatum), Skullcap (Scutellaria lateriflora), Soil, Spinach (Spinacia oleracea), Stock (Matthiola Ait. f.), Strawberry (Fragaria x ananassa), Sunflower (Helianthus annuus), Tomato (Solanum lycopersicum), Tulip tree (Liriodendron tulipifera), Udo (Aralia cordata), Watermelon (Citrullus lanatus) Australia, Austria, Belgium, Brazil, Canada, China, Denmark, France, Germany, Greece, Iran, Israel, Italy, Japan, Moldova, Netherlands, New Zealand, Russia, Spain, Tunesia, UK, Ukraine, USA (CA, IL, NY, OR, TX, WA, WI), Uzbekistan, former Yugoslavia 74 / 25