Fusarium kamalianum S. Rana, and S.K. Singh

Rana, Shiwali & Singh, Sanjay K., 2024, Fusarium kamalianum, a new species of Fusarium from India from ornamental Chamaedorea seifrizii, Phytotaxa 659 (1), pp. 1-23 : 15-17

Fusarium kamalianum S. Rana, and S.K. Singh sp. nov. Figures 2–3 .

MycoBank Number:—MB 847910

Holotype:— AMH 10483

Etymology:—This specific epithet represents Professor Kamal, a popular mycologist in India, to honor his extraordinary contribution to Indian mycology.

Host/Distribution: Wilted Chamaedorea seifrizii is in Pune, India.

Original description:— Asexual morph Mycelium white delicate floccose. Hyphae simple to branched, septate, hyaline to subhyaline, smooth-walled, sometimes arranged in loose parallel bundles, sometimes showing anastomoses, 1–8.82 µm wide (x̄ = 3.92 µm, n=10). Macroconidiogenus cells integrated (reduced to conidiophore), short, bulged, sometimes appear denticulate, ampuliform (x̄ = 3.75 × 2.2 µm, n=15). Conidiophores simple to branched, arising laterally from superficial hyphae, 1–3 septate, 30.5–127.75 × 1.5–4.65 µm (x̄ = 75.95 × 2.77 µm, n=15). Microconidia produced in loose gleosporic mass, produced on terminal phialides, variable in shape and size, fusoid, allantoid, straight to curved, base narrowly truncate, apex sub-obtuse to obtuse, smooth-walled, hyaline, produced abundantly, sometimes guttulate, 0 to 1-septate, 3.45–18.70 × 1.18–5.0 µm (x̄ = 9.78 × 3.06 µm, n=30). Macroconidia straight to curved, 3–5 septate, foot cell prominent, base narrowly truncate, apex sub obtuse, beak short, 18.90–46.05 × 1.95–4.75 µm (x̄ = 27.64 × 3.83 µm, n=30). Chlamydospores are produced abundantly on SNA, smooth to rough-walled, intercalary, solitary, or in chain (2–3), sometimes muriform.

Sexual morph: Unknown.

Culture characteristics:—Colonies growing on PDA reach 52 mm after five days at 25° C; colonies from above are reddish brown (9D6) to white (9 A 1), irregular, filamentous, centre raised, margins flat cottony; colonies from below caput mortuum (26 F 2) to greyish yellow (4 B 3). After five days, the colony started producing pigments; greyish orange (6 B 4) diffusible pigment was observed after ten days. After eight days, orange-white (5 A 6) to melon-yellow (5 A 2) colored exudates were observed. Colonies on SNA reach 37 mm after four days of incubation at 25° C. Colonies from the front and reverse are white (1 A 1), flat, slightly cottony, margin regular, entire, and smooth.

Known distribution:—Pune, Maharashtra, India.

Material examined:— INDIA, Maharashtra, Pune (31.9754 N ” 76.6507 E ”), Chamaedorea seifrizii, S.K. Singh , 22 October 2021, AMH 10483 (holotype), deposited in Ajrekar Mycological Herbarium ( AMH), India. Ex-type culture is deposited in the National Fungal Culture Collection of India ( NFCCI 5154).

GenBank numbers: tef-1α = OQ128117, tub2 = OQ128115, rpb2 = OQ128116, LSU = OR436906, and ITS = OR436905.

Other specimen examined: INDIA, Maharashtra, Pune (31.9754 N ” 76.6507 E ”), Chamaedorea seifrizii, S.K. Singh , 22 October 2021, NFCCI 5741 ; GenBank numbers: tef-1α = PP681683, tub2 = PP681681, rpb2 = PP681682, LSU = PP668089 , and ITS = PP668088 .

Notes:— Fusarium kamalianum is placed in the Fusarium oxysporum species complex based on morphology and phylogeny. The tef-1α sequence of F. kamalianum showed 92.2% identity with Fusarium foetens strain CBS 110286 and 90.95% identity with Fusarium oxysporum strain CBS 144134. Fusarium kamalianum shares several morphological characteristics with members of the FOSC, including chlamydospores that are mostly formed terminally and short monophialides that arise directly from hyphae. Polyphialides are absent in the FOSC ( Gerlach & Nirenberg 1982, Nirenberg & O’Donnell 1998) but occasionally form in some F. foetens and F. kamalianum strains. In most strains belonging to FOSC, ovoidal to ellipsoidal microconidia are formed in heads by mono phialides dispersed in the aerial mycelium; in the case of F. kamalianum fusoid, allantoid, straight to curved microconidia are produced by phialides arising from the aerial mycelia. Other characters that distinguish F. kamalianum from members of the FOSC include the length of monophialides formed by the aerial mycelium, which can be up to 120 μm in F. kamalianum but only 14 mm in the FOSC ( Gerlach & Nirenberg 1982) and up to 35 mm in F. foetens ( Schroers et al. 2004) . Colonies of F. foetens produce a strong, pungent, and irritating odor on OA and PDA, which has not been described in any member of the FOSC; similar to FOSC, no odor was found from colonies of F. kamalianum . Usually, most strains of F. oxysporum , too, have no perceptible odor ( Gerlach & Nirenberg 1982). Based on the phylogenetic analyses and morphological characteristics, F. kamalianum is described as a distinct new species falling under FOSC.

Phylogenetic analysis

The ITS, LSU, tef-1α, rpb2, and tub2 gene regions were used to determine this novel Fusarium’s identity. In the case of the first phylogenetic tree in which 103 sequences belonging to different species complexes of Fusarium were compared, the concatenated file contained sequence data with 33283 columns, 1438 distinct patterns, 935 parsimony-informative, 245 singleton sites, 2103 constant sites. TIM2e+ I + G 4, TIM2e+ G 4, TIM2e+ I + G 4, TNe+ I + G 4, and TNe+ G 4 were the best models selected for Tef- 1α, rpb2, ITS, LSU, and tub2 respectively. The partition-specific rates were 2.160, 1.076, 0.601, 0.165, and 0.989. Based on the above model, the phylogeny was carried out using the Maximum Likelihood Method. The log-likelihood of the consensus tree was -27073.797 ( Figure 4 ). For the second phylogenetic tree, which majorly consisted of the species belonging to the Fusarium oxysporum species complex, the concatenated file contained sequence data of 40 taxa with 3112 columns, 331 distinct patterns, 117 singleton sites, 177 parsimony-informative, 2818 constant sites. K 2 P + I, K 2 P + G 4, JC, K 2 P + I, and K 3 P + I were the best models selected for Tef- 1α, rpb2, ITS, LSU, and tub2 respectively. The partition-specific rates were 2.039, 0.867, 0.560, 0.522, and 1.031. The phylogeny was carried out using the maximum likelihood method based on the above model mentioned. The log-likelihood of the consensus tree was -6767.498 ( Figure 5 ). Tree branches were tested based on 1000 ultrafast bootstrap support replicates (UFBoot) and with an SH-like approximate likelihood ratio test (SH-like aLRT) with 1000 replicates. The combined phylogenetic tree generated using ITS, LSU, tef-1α, rpb2, and tub2 sequence data nested this isolate in a unique, distinct, and well-supported clade in the genus Fusarium under Fusarium oxysporum species complex supported with good SH-like aLRT, and ultrafast bootstrap (UFBoot) ( Figure 4 , 5 ).

The phylogenetic inference supported by morphology and phylogeny based on multiple gene regions, Fusarium kamalianum , is identified and documented here as a new species of Fusarium to science.

Figures

FIGURE 2. A. Rotted stem of Chamaedorea seifrizii (Bamboo palm); B. Wilted leaf of Chamaedorea seifrizii (Bamboo palm); C. In vitro culture of the pathogen of Chamaedorea seifrizii (F. kamalianum) on PDA; Pure colony of F. kamalianum growing on PDA after a week; D. Front view; F. Reverse view; E. Pure colony of F. kamalianum growing on SNA.

FIGURE 3. Morphological characters of Fusarium kamalianum NFCCI 5154. A–C. Microconidia on simple, long slender phialides; D. Branched phialides bearing microconidia; E. Elongate microconidia in the false head; F. Solitary monophialides; G, H. Smooth to rough walled chlamydospores; I. Coiled mycelia bearing phialides; J, K. Microconidia; L. Micro and macroconidia.—Scale bars: A–F, I-J = 20 µm, G, H, K, L = 10 µm.

FIGURE 4. Molecular phylogenetic analysis of new species, Fusarium kamalianum, generated by maximum-likelihood (ML) method based on combined ITS, LSU, tef-1α, rpb2, and tub2 sequence data. Different species complexes of Fusarium were used in the study to figure out the taxonomic position of F. kamalianum. The new species, Fusarium kamalianum, is represented in blue bold.

FIGURE 5. Molecular phylogenetic analysis of new species, Fusarium kamalianum generated by maximum-likelihood (ML) method based on combined ITS, LSU, tef-1α, rpb2, and tub2 sequence data. Isolates majorly belonging to Fusarium oxysporum species complex were used in the construction of the phylogenetic tree. The statistical support values are shown next to each node, UFBS, and SH-aLRT produced from 1000 replicates using IQ-TREE. The new species, Fusarium kamalianum is represented in blue bold.