Trichoderma bombaxalis Jing Z. Sun & H.W. Liu, 2022

Yu, Shuang, Wang, Rui, Liu, Hong-Wei, Zhang, Xue & Sun, Jing-Zu, 2022, Trichoderma bombaxalis sp. nov., isolated from rhizosphere soils of Lycium barbarum, Phytotaxa 547 (2), pp. 147-157 : 152-155

Trichoderma bombaxalis Jing Z. Sun & H.W. Liu , sp. nov. ( FIGURE 2 )

Index Fungorum number: IF559555

Etymology: —“ bombaxalis ” (Latin), bombax+alis, meaning like mature fruits of kapok on culture media.

Type: — CHINA. Yinchuan: Ningxia Hui Autonomous Region , 105°97’E, 38°28’N, from rhizosphere soil of Lycium barbarum , 10 May 2021, Jing Z. Sun ( HMAS 351590 , holotype), ex-type culture CGMCC3.20851. GenBank accessions: ITS = OM109651 , OM109652 , TEF-1α = OM142599 , OM142600 , RPB2 = OM142601 , OM142601 .

Description: —On CMD after 72 h, colony diameter 21–25 mm at 25 °C, and 20–37 mm at 30 °C. After 7 days, mycelium loose, a layer of aerial mycelium covering the entire plate at 25 °C and 30 °C ( FIGURE. 2C, G ). Many conidiophores formed by 5 days, unknown aromatic odour, and no pigment.

On PDA after 72 h, colony diameter 6–7 mm at 25 °C, and 4–5 mm at 30 °C. At 25 °C, white colony, cotton-like, dense hyphae. At 30 ℃, white flocculent colony, uniform mycelial density, coconut aroma, and no pigment. After 7 days, colony diameter 13–14 mm at 25 °C ( FIGURE 2A ), and 9–10 mm at 30 °C, not producing concentric rings or radial rays of mycelium ( FIGURE 2E ).

On SNA after 72 h, colony diameter 15–22 mm at 25 °C, and 17–21 mm at 30 °C. White colony, mycelium loose, light coconut aroma. After 7 days, colony edge was irregular, and mycelium was loose, coconut aroma and no pigment ( FIGURE 2B, F ). Conidial production noted after 5 days. Conidiophores branched verticillium-like, phialides subulate, variable in length, in whorls or opposite, 2–3(–4) branches, (8.8–)11–18(–23.2) × (1.3–)2.0–3.0(–3.4) μm (x = 14.3 × 2.4 μm, n = 20) ( FIGURE 2D, H, I, J ). Conidia obovate to ellipsoidal, roughened ( FIGURE 2K, L ), (2.0–)2.5–3.6(–4.5) × (1.0–)1.4–2.0(–2.4) µm (x = 3.1 × 1.7 µm, n = 50), length/width ratio (1.2–)1.5–1.8 (–2.4) (x = 1.6, n = 50). No sexual morphogenesis.

Additional specimen examined: — CHINA. Yinchuan: Ningxia Hui Autonomous Region , 105°97’E, 38°28’N, from rhizosphere soil of Lycium barbarum , 10 May 2021, Jing Z. Sun ( HMAS 351591 ), culture CGMCC3.20852 .

Teleomorph: —Undetermined.

Notes: — Trichoderma bombaxalis differs from other species in section Hypocreanum ( T. austriacum , T. eucorticioides , T. sulphureum , T. subsulphureum , T. avictoriense ) in the size of phialides and conidia ( TABLE 2 ).

Ability to degrade cellulose and hemicellulose

Trichoderma bombaxalis was inoculated on xylan medium and CMC-Na medium for 7 days ( FIGURE 3 ). Transparent zones were present around the colony on CMC-Na medium following Congo red dyeing and decolouration ( FIGURE 3D ), indicating a capacity to hydrolyze cellulose. However, no transparent zones were observed on the xylan medium, indicating weak or no ability to use hemicellulose. Trichoderma bombaxalis may be a potential candidate for cellulase exploration.

Figures

FIGURE 2. Trichoderma bombaxalis (CGMCC 3.20851). Cultures at 25 °C after 7 days (A. on PDA, B. on SNA, C. on CMD). Cultures at 30 °C after 7 days (E. on PDA, F. on SNA, G. on CMD). D, H, I, J. Conidia and phialides. K, L. Conidia. Scale bars: 10 µm.

FIGURE 3. A. Cultures at 25 °C after 7 days on xylan medium. B. Following Congo red dyeing and decolorization on xylan medium. C. Cultures at 25 °C after 7 days on CMC-Na medium. D. Following Congo red dyeing and decolorization on CMC-Na medium.