Fusarium guizhouense Lin Huang, Jiao He & D.W. Li, 2024

He, Jiao, Li, De-Wei, Cui, Wen-Li, Zhu, Li-Hua & Huang, Lin, 2024, Morphological and phylogenetic analyses reveal three new species of Fusarium (Hypocreales, Nectriaceae) associated with leaf blight on Cunninghamia lanceolata in China, MycoKeys 101, pp. 45-80 : 45

Fusarium guizhouense Lin Huang, Jiao He & D.W. Li sp. nov.

Fig. 7

Etymology.

Epithet is after Guizhou Province where the type specimen was collected.

Holotype.

China, Guizhou Province, Qiandongnan Miao and Dong Autonomous Prefecture, Cengong County, Kelou Town, 27°22′58″N, 108°22′9″E, isolated from leaf spots of Cunninghamia lanceolata , May 2017, Wen-Li Cui, (holotype: CFCC 57575). Holotype specimen is a living specimen maintained via lyophilization at the China Forestry Culture Collection Center (CFCC). Ex-type (GZ7-20-1) is maintained at the Forest Pathology Laboratory, Nanjing Forestry University.

Host/distribution.

From C. lanceolata in Kelou Town, Cengong County, Qiandongnan Miao and Dong Autonomous Prefecture, Guizhou Province, China.

Description.

Sexual state not observed. Asexual state: Sporulation abundant from sporodochia, rarely from conidiophores formed directly on the substrate mycelium. Conidiophores in the aerial mycelium absent. Sporodochia bright orange colored, formed abundantly on carnation leaves. Conidiophores in sporodochia (13.8-)18.8-25.8(-29.8) μm, (mean ± SD = 22.3 ± 3.5 μm, n = 39), irregularly branched and densely packed, bearing apical whorls of 1-4 phialides; sporodochial phialides subulate to subcylindrical, (8.2-)10.6-14.7(-16.9) × (2.7-)3.1-4.0(-4.8) μm, (mean ± SD = 12.6 ± 2.0 × 3.6 ± 0.5 μm, n = 40), smooth, thin-walled. Sporodochial macroconidia colorless, straight or slightly curved, wider at the middle or apical part, tapering towards the base, with a blunt and often curved apical cell and a foot-like to slightly notched basal cell, 4-5-septate. Four-septate conidia: (30.8-)33.3-40.9(-40.6) × (4.5-)5.3-6.4(-6.9) μm, (mean ± SD = 37.1 ± 3.8 × 5.9 ± 0.5 μm, n = 52), five-septate conidia: (33.4-)38.0-45.4(-51.3) × (5.0-)5.7-6.9(-7.5) μm, (mean ± SD = 41.7 ± 3.7 × 6.3 ± 0.6 μm, n = 60), smooth, thin-walled. Chlamydospores absent.

Culture characteristics.

Colonies on PDA growing in the dark with an average growth rate of 16.7 mm/d at 25 °C. Colony color white at first, becoming buff, felty to cottony. Aerial mycelium abundant, loose to densely floccose; margins irregular and fimbriate. Reverse pale buff with white periphery. Odor absent. Colonies on SNA incubated at 25 °C in the dark were irregular, growing at 9.7 mm/d. Colony surface pure white, aerial mycelium scant, forming irregular rings at the periphery of the colony; margins lobate or serrate. Reverse pure white, without diffusible pigments. Colonies on OMA incubated at 25 °C in the dark were irregular, aerial mycelium abundant, loose to densely floccose, growing at 13.1 mm/d. Colony in reverse was white with litter gray pigmentation. Colonies on CMA incubated at 25 °C in the dark were round, colony surface and reverse white, flat, radially striated, membranous to dusty, aerial mycelium scant or absent; colony margins irregular, lobate or serrate, growing at 9.6 mm/d.

Additional materials examined.

China, Guizhou province, Qiandongnan Miao and Dong Autonomous Prefecture , Cengong County, Kelou Town , 27°22′58″N, 108°22′9″E, isolated from leaf spots of Cunninghamia lanceolata , May 2017, Wen-Li Cui, isolates: GZ7-20-1-1, GZ7-20-1-2, GZ7-20-1-3 .

Notes.

The isolates of F. guizhouense were phylogenetically close to F. sambucinum (ex-holotype, CBS 146.95), F. poae (ex-type, NRRL 26941), and F. venenatum (ex-type, CBS 458.93) (Fig. 5 ). Between F. guizhouense isolates and ex-holotype of F. sambucinum CBS 146.95, there were 34/577 differences in TEF-1α, 8/897 in RPB2. The RPB1 sequence of F. sambucinum CBS 146.95 was missing. Between F. guizhouense isolates and ex-type of F. poae NRRL 26941, there were 24/897 differences in RPB2, 26/641 in RPB1. The TEF-1α sequence of F. poae NRRL 26941 was missing. Between F. guizhouense isolates and ex-type of F. venenatum CBS 458.93, there were 20/577 differences in TEF-1α, 8/897 in RPB2. The RPB1 sequence of F. venenatum CBS 458.93 was missing. The PHI analysis showed that there was no significant recombination between F. guizhouense isolates and its related species (Φw = 0.7313) (Fig. 3C ). Morphologically, Sporodochial phialides of the F. guizhouense isolates (10.6-14.7 × 3.1-4.0 μm) were smaller than those of F. sambucinum NRRL 22203 (ex-lectotype) (14.0-18.0 × 3.8-4.5 µm) ( Nirenberg 1995). Fusarium sp. FSAMSC_11 (NRRL 22192) is closely related to F. guizhouense , but it has no morphological data available ( Laraba et al. 2021). Further study on this isolate (NRRL 22192) is necessary to determine its taxonomic placement. In conclusion, the phylogenetic and morphological evidence support this fungus being a new species within the F. sambucinum species complex.

Figures

Figure 3. Splitgraphs showing the results of the pairwise homoplasy index (PHI) test of three newly described taxa and closely related species using both LogDet transformation and splits decomposition A the PHI of Fusarium fujianense sp. nov. with their phylogenetically related isolates or species B the PHI of F. hunanense sp. nov. with their phylogenetically related isolates or species C the PHI of F. guizhouense sp. nov. with their phylogenetically related isolates or species. PHI test value (Φw) <0.05 indicate significant recombination within a dataset. * indicates isolates of this study. T indicates ex-types. HT indicates ex-holotypes.

Figure 5. Phylogenetic relationships of 30 isolates of the Fusarium sambucinum species complex with related taxa with concatenated sequences of the TEF- 1 α, RPB 2, and RPB 1 loci using Bayesian inference (BI) and maximum likelihood (ML) methods. Bootstrap support values from ML ≥ 70 % and BI posterior values ≥ 0.9 are shown at nodes (ML / BI). F. concentricum CBS 450.97 T was the outgroup. * indicates strains of this study. T indicates the ex-type strains. HT indicates ex-holotypes.

Figure 7. Fusarium guizhouense (GZ 7 - 20 - 1) A-D colonies on PDA, SNA, OMA, and CMA, respectively, after 5 days at 24 ° C in the dark E sporodochia formed on the surface of carnation leaves F-J sporodochial conidiophores, phialides, and macroconidia K macroconidia (4 - 6 - septate). Scale bars: 200 μm (E); 10 μm (F, G, K); 50 μm (H-J).