Fusarium tanahbumbuense Sand. - Den., L. Lombard, Kema & Crous

Fallahi, Maryam, Armand, Alireza, Al-Otibi, Fatimah, Hyde, Kevin D. & Jayawardena, Ruvishika S., 2025, Pathogenic fungi (Sordariomycetes) associated with annual and perennial crops in Northern Thailand, MycoKeys 117, pp. 191-265 : 191-265

Fusarium tanahbumbuense Sand. - Den., L. Lombard, Kema & Crous , Persoonia 43: 63 (2019)

Fig. 24

Description.

Pathogenic to durian ( Durio zibethinus ) and pepper ( Capsicum annuum ), and causes small, water-soaked lesions on leaves and stems that enlarge into necrotic spots with dark margins, potentially leading to defoliation and stem girdling under favorable, humid conditions. Sexual morph not observed. Conidiophores on aerial mycelium septate, irregular, verticillately branched. Conidiogenous cells mono- or polyphialidic, subulate or subcylindrical, smooth and thin-walled, 7–24 × 2–4 µm (mean = 13 × 3 µm, n = 15). Conidia on aerial mycelium, ellipsoidal to falcate, smooth and thin-walled, 1–3 septate, 7–27 × 2–4 µm (mean = 33 × 3 µm, n = 30). Sporodochia are formed plentifully on CLA after 7 days and have a pale orange color. Conidia on sporodochia falcate, produced by both mono- and polyphialides, apical cells conical to papillate, basal cells indistinct or foot-shaped, 3–5 - septate, 26–38 × 2–3.7 µm (mean = 33 × 3 µm, n = 30). Chlamydospores are absent.

Culture characteristics.

Colonies on PDA reach 50 mm in diameter after 7 days of growth at 25 ° C in the dark, cottony and rosy buff in the center, becoming white towards the margin, with moderate aerial mycelium, and appearing wet with age. The reverse is rosy buff, becoming white towards the margins.

Material examined.

Thailand • Chiang Rai, Mueang Chiang Rai District, Doi Hang , on leaf spot on durian ( Durio zibethinus ), December 2022, Maryam Fallahi, dried culture MF 31-1 ( MFLU 24-0248 ), living culture MFLUCC 24-0231 • Amphoe Mueang Sakon Nakhon, Chang Wat Sakon Nakhon , leaf spot on pepper ( Capsicum annuum ), February 2023, Maryam Fallahi, dried culture MF 145-1 ( MFLU 24-0250 ), living culture MFLUCC 24-0247 .

Notes.

In the present study, strains MFLUCC 24-0231 and MFLUCC 24-0247 clustered with Fusarium tanahbumbuense (InaCC: F 965, ex-type) in F. incarnatum complex with 100 % ML, 100 % IQ bootstrap support, and 1.0 BYPP (Fig. 21 ). The base pair differences between F. tanahbumbuense strains MFLUCC 24-0231 and ex-type InaCC: F 965 revealed a 0.36 % (2 / 541 bp) difference in tef 1, a 0.71 % (6 / 838 bp) difference in rpb 2, and a 0.27 % (2 / 742 bp) difference in rpb 1. The base pair differences between F. tanahbumbuense ( MFLUCC 24-0247 ) and F. tanahbumbuense (InaCC: F 965, ex-type) revealed a 0.42 % (2 / 470 bp) difference in tef 1, a 0.62 % (8 / 801 bp) difference in rpb 2, and a 0.27 % (2 / 742 bp) difference in rpb 1. Fusarium tanahbumbuense was first reported from Indonesia on an infected pseudostem of Musa sp. ( Maryani et al. 2019 a). This study provides two new hosts and geographical records for F. tanahbumbuense on durian and pepper.

Figures

Figure 21. Phylogenetic tree of the Fusarium incarnatum species complex generated by maximum likelihood of combined tef 1, rpb 1, and rpb 2 sequence data. The ultrafast maximum likelihood (ML) and IQ bootstrap support values ≥ 50 % (BT), as well as Bayesian posterior probabilities ≥ 0.95 (BYPP) are shown, respectively, near the nodes. The ex-type strains are marked with an asterisk. The tree is rooted in F. concolor (NRRL 13994).

Figure 24. Fusarium tanahbumbuense (MFLUCC 24-0231) a leaf spots on durian b stem and leaf spots on pepper c front, and d back views of the colony after 10 days of growth on PDA at 25 ° C e spordochium f – g spordochium conidia h, i conidiophores and conidiogenous cells. j aerial conidia. Scale bars: 20 μm.