Fusarium atrovinosum L. Lombard & Crous, Fungal Systematics and Evolution 4: 190 (2019)

Index Fungorum number: IF 831559; MycoBank number: MB 831559; Facesoffungi number: FoF 09577; Fig. 1

Saprobic on dead stalk of Sorghum bicolor. Sexual morph Undetermined. Asexual morph Conidiophores 20–50 µm tall, carried on aerial mycelium, unbranched or irregularly or sympodially branched, bearing a terminal single phialide or whorl of 2–3 phialides. Conidiogenous cells 9–23×2–4 µm, polyphialides, subulate to subcylindrical, smooth. Conidia 4–14×2–3 µm, formed in false heads on the phialide tips, hyaline, fusiform to ellipsoidal to obovoid, smooth and thin-walled, mostly 0-septate, rarely 1–2-septate then larger. Chlamydospores 5–22 µm diam., abundant, globose to subglobose, smooth to slightly verrucose, formed terminally or intercalarily in chains of three or more; wall 1–1.5 µm.

Culture characteristics – Colonies on PDA reaching 90 mm at 24 °C after 28 d in the dark; surface vinaceous, mycelium dense to woolly, without odour; reverse livid red to dark vinaceous. On SNA colonies sparse, white to pale rosy buff in the centre, powdery due to abundant; reverse pale rosy buff. On CLA aerial mycelium abundant, white, lacking sporodochia on the carnation leaf pieces. On WA colonies sparse and powdery; pale rosy vinaceous in the centre; reverse pale rosy vinaceous.

Material examined – AUSTRALIA, Goondiwindi, on dead stalk of Sorghum bicolor, 19 February 2018, N. Vaghefi, BRIP 70767a, new record.

GenBank numbers – CAL = MW403492 , RPB2=MW403493, TEF1-α=MW403494.

Notes – Fusarium atrovinosum belongs to the Fusarium chlamydosporum species complex (O’Donnell et al. 2009; Lombard et al. 2019b). In a four-locus phylogeny (Fig. 2), the isolate (BRIP 70767a) was recovered in a well-supported clade (98% MLBS, 1.00 BYPP) that contained the type strain of F. atrovinosum (CBS 445.67). This isolate (BRIP 70767a) was morphologically and culturally similar to the type strain of F. atrovinosum (CBS 445.67) described in Lombard et al. (2019b). Fusarium atrovinosum was described on Triticum aestivum (wheat) in Australia (Lombard et al. 2019b). Subsequently, F. atrovinosum has been reported from Brazil in association with rice seed and other hosts (Costa 2020). These studies indicate that F. atrovinosum may have an association with grass (Poaceae) hosts. This is the first record of F. atrovinosum on Sorghum (Fig. 1).

Figure 1 – Fusarium atrovinosum (BRIP 70767a, new record). a, b Culture on PDA from surface and reverse. c Conidiophores. d Conidia. e Chlamydospores. Scale bars: a, b=1 cm, c–e=10 µm

Figure 2 – Phylogram generated from Bayesian analysis based on combined CAL, RPB1, RPB2 and TEF1-α sequence data representing Fusarium chlamydosporum species complex and related taxa. The second measure of branch support was obtained through Maximum Likelihood (ML) analysis of the same alignment using RAxML v. 8 (Stamatakis 2014) based on the GTR substitution model with gamma-distribution rate variation for each partition. Reference strains were obtained from Lombard et al. (2019b). The tree is rooted to Fusarium concolor (NRRL 13459). The analysis was performed using MrBayes v. 3.2.4 (Ronquist et al. 2012) based on the K80, K80+G, and HKY+G nucleotide substitution models selected for CAL, RPB2, and TEF1-α, respectively, using PAUP v. 4.0 (Swofford 2003) and MrModeltest v. 2.3. (Nylander 2009). Maximum likelihood bootstrap support values (MLBS) greater than 80% are placed above the nodes and Bayesian posterior probabilities (BYPP) equal to or greater than 0.95. Branches with MLBS=100% and BYPP=1.00 are thickened. Scale bar indicates the number of substitutions per nucleotide. Ex-type strains are in bold and newly isolate is in blue