In the present study, we surveyed the ascomycetes from bamboo of Phyllostachys across Sichuan Province, China. A biphasic approach based on morphological characteristics and multigene phylogeny confirmed seven species, including one new genus, two new species, and five new host record species. A novel genus Paralloneottiosporina is introduced to accommodate Pa. sichuanensis that was collected from leaves of Phyllostachys violascens. Moreover, the newly introduced species Bifusisporella sichuanensis was isolated from leaves of P. edulis, and five species were newly recorded on bamboos, four species belonging to Apiospora, viz. Ap. yunnana, Ap. neosubglobosa, Ap. jiangxiensis, and Ap. hydei, and the last species, Seriascoma yunnanense, isolated from dead culms of P. heterocycla. Morphologically similar and phylogenetically related taxa were compared. Comprehensive descriptions, color photo plates of micromorphology are provided.

Trichoderma fungi are significant saprophytic resources in nature, with only a minority of species documented as pathogenic fungi. Due to their widespread distribution, this genus of fungi has attracted considerable attention in recent years. During an investigation of fungal resources within the staple food bamboo species for giant pandas in China conducted from 2023 to 2024, a high diversity of Trichoderma species was observed. In this study, eight collected specimens were compared morphologically with known species, and DNA sequence analysis was performed using a multi-gene (ITS, tef 1-α, and rpb 2) dataset to establish phylogenetic relationships, ultimately leading to the identification of four Trichoderma species. The research uncovered four novel Trichoderma species: Trichoderma bashania , T. fargesia , T. mianyangensis and T. yaanensis . Phylogenetic analysis revealed that each of these new species forms a distinct lineage, with Trichoderma bashania , T. fargesia , T. mianyangensis and T. yaanensis all belonging to the Koningii section. All these newly identified species were isolated from the litter of the staple food bamboo species for giant pandas. This study provides morphological descriptions and illustrations of these four new species, along with DNA phylogenetic relationships based on the analysis of the multi-gene dataset. The findings indicate that Trichoderma fungi are widely present in the ecosystem of the staple food bamboo species for giant pandas and warrant close attention.

Iron walnut (Juglans sigillata Dode) is a temperate deciduous tree indigenous to China. It is mainly distributed in southwestern China, and valued for its wood and nuts (Feng et al. 2018). In September 2020, symptoms of canker on J. sigillata were observed in an orchard measuring 2 hectares located in Chongzhou City, Sichuan Province (31°5′ 25″N, 105°27′36″E, 365 m altitude). Twenty percent of plants showed canker symptoms during the 50 surveyed plants. The infected trunk showed necrotic lesions with black pycnidia, that led to necrosis of branches and death of the whole plant in severe cases (Fig. 1). Six specimens from different diseased plants were collected for pathogen isolation and morphological observation. Pure cultures were obtained from single conidium on potato-dextrose agar (PDA) media according to the method described by Chomnunti (Chomnunti et al. 2014). Colonies grew fast and reached 3 cm after 5 days. The aerial mycelium was abundant, which was initially white and then grayish. Conidiomata on the host were measured 160–280 µm × 140–190 µm (average: 220 × 165 µm, n = 20), stromatic, uniloculate, dark brown to black, immersed, and erumpent when mature. Pycnidial walls 32–58 µm wide, were composed of 5–7 layers of brown to dark brown cells. Conidia were hyaline, and ellipsoidal with rounded apex and base, widest at the middle, thick-walled, and unicellular, with a size 21.5–31 µm × 11.5–15.7 µm (average: 27 × 13.5 µm, n = 50). Morphological characteristics fit the description of Lasiodiplodia pseudotheobromae A.J.L. Phillips, A. Alves & Crous (Aives et al. 2008). The internal transcribed spacers (ITS), 18S small subunit rRNA (SSU), 28S large subunit rDNA (LSU), translation elongation factor 1-alpha (tef1-α), and beta-tubulin (tub2) were amplified by polymerase chain reaction and sequenced with primers ITS1/ITS4, NS1/NS4, LR0R/LR5, EF1-728F/EF1-986R and Bt2a/Bt2b, respectively (Li et al. 2018). The sequences of the representative isolate (SICAUCC 22-0079) were deposited in NCBI with accession numbers ON090365 (ITS), ON090406 (SSU), ON090418 (LSU), ON112377 (tef1-α), and ON112378 (tub2), respectively. Nucleotide blast showed 100% similarity of all the analyzed and NCBI submitted isolates with L. pseudotheobromae (CBS116459; holotype) (accession numbers EF622077, EU673199, EU673256, EF622057, EU673111). Phylogenetic analyses based on a combined dataset showed 100% bootstrap support values in a clade with L. pseudotheobromae complexes (Fig. 2). Based on morphological and molecular analyses, the fungal pathogen was identified as L. pseudotheobromae. To conduct Koch's postulates, four 2-year-old healthy plants of J. sigillata were inoculated with 10 μL spore suspension (105 conidia/mL) onto the wounded sites via sterile pin. As control, four healthy plants were treated with sterile distilled water. The inoculated and untreated plants were placed in a growth chamber at 25°C with relative humidity >90% and 12-h photoperiod. Trunk canker symptoms appeared on inoculated plants after 15–20 days, and the pathogen was re-isolated and the controls were symptomless, confirming Koch’s postulates. L. pseudotheobromae is widely distributed in various plants all over the world, usually as a pathogen associated with damping-off, wilt, die-back, root rot, collar rot, witches’ brooms, or fruit rots (Zhao et al. 2010). To our knowledge, this is the first report of trunk canker on J. sigillata caused by L. pseudotheobromae in China. Trunk canker caused by L. pseudotheobromae is becoming a potential threat to walnut production, and some necessary measures for integrated management should be made.

Phyllostachys aureosulcata McClure 'Spectabilis' C.D. Chu. et C.S. Chao is predominantly native to subtropical to warm temperate areas and is widely cultivated for landscaping in China (Neményi et al. 2015). In November 2020 (10 – 16 ℃), culm blight symptoms were observed on P. aureosulcata 'Spectabilis' in Wangjiang Tower Park (all kinds of plant areas are about 9.8 ha), Chengdu City (104°09′30.42″ E, 30°63′18.89″ N). Fifty plants were surveyed, and disease incidence was recorded as approximately 30%. Initially, chlorotic necrotic patches appeared on the culms, and gradually the patches became white, expanded to both ends, and encircled the whole culm with black edge and conidiomata, which eventually led to wilt and death. Five samples from different bamboos were collected and one of them were used for morphological observation. Five single conidia isolates were carried out on potato dextrose agar (PDA) at 25±1℃ (Chomnunti et al. 2014). Colonies were initially white and then yellowish in the center with abundant aerial mycelia. On the culm, conidiomata were dry, black, and filamentous. Conidiophores were reduced to conidiogenous cells. Conidiogenous cells were smooth, hyaline, ampulliform to doliiform. Conidia were ellipsoid to globose, dark brown, smooth and aseptate, measuring 5.2 to 9.4 × 4.4 to 7.3 μm, (=8.2 × 6.5μm, n=50). On the PDA medium, conidia were globose to subglobose, olive green to pale brown, and smooth, larger than those from the host in size, measuring 9.0 to 18 × 7.5 to 9.5 μm ( =36.6 × 18.8 μm, n=50). These asexual structures were extremely similar to Apiospora locuta-pollinis (F. Liu & L. Cai) X.G. Tian & Tibpromma (Zhao et al. 2018). DNA was extracted from the representative strain (SICAUCC 22-0036), and the internal transcribed spacer (ITS), translation elongation factor 1-alpha (tef1-α), beta-tubulin (tub2), 28S large subunit rDNA (LSU) were amplified and sequenced with primers ITS1/ITS4 (White et al. 1990), EF1-728F (Carbone & Kohn 1999)/EF2 (O’Donnell et al. 1998), T1 (O’Donnell & Cigelnik 1997)/Bt2b (Glass & Donaldson 1995) and LR0R/LR5 (Rehner & Samuels 1994). The newly generated sequences were deposited in GenBank with accession nos. ON228609 (ITS), ON324018 (tef1-α), ON237657 (tub2), and ON228665 (LSU). Nucleotide blast showed 98.97%, 100% and 99.46% identities with A. locuta-pollinis (LC11683, ex-holotype) (accession nos. MF939595, MF939622, MF939616), and LSU data missing. Phylogenetic analyses using maximum likelihood showed a 92% bootstrap support value in a clade with A. locuta-pollinis (Fig 2). Eight healthy plants (2-year-old) were used for the pathogenicity test. Culms of four healthy bamboos were wounded via sterile double-edged blade and sprayed with conidial suspension (105 conidia/ml) prepared from 4-week-old cultures that were incubated on PDA at 25℃. The other four bamboos were sprayed with sterile distilled water as controls. Inoculated plants were placed in a growth chamber (25℃, 90% relative humidity, 12-h photoperiod). About 60 days later, necrotic patches similar to those observed in the field were found on the inoculated culms, and no symptoms were observed on the controls. The pathogen was reisolated from the diseased culms with identical morphology as previously described. To our knowledge, this is the first report of culm blight on P. aureosulcata 'Spectabilis' caused by A. locuta-pollinis. The risk of this pathogen needs further evaluation, and effective control measures should be taken.

Juglans regia L. is commercially important for its edible nuts, which is a major species of walnut trees in Sichuan Province (Luo et al. 2020). In September 2021, brown leaf spot symptoms were obse...

Juglans sigillata Dode, an endemic walnut species native in southwest China, is mainly used as nuts in Sichuan Province (Jin et al., 2019). In May 2021, symptoms of branches blight were observed in an orchard measuring 10 hectares located in Mianyang City, Sichuan Province (31°5′ 25″N, 105°27′36″E, 365 m above sea level). About 40% of plants were diseased in the quadrat consisting of twenty walnut trees, and 20% of branches were dead on each affected tree. Initially, light brown spots appeared; then, the spots expanded to surround the whole branches; finally, the branches changed from brown to reddish-brown and died. Four symptomatic branches were sampled randomly from different trees. Next, four fungal isolates were obtained from the acervuli of each branch using the single-conidium isolation (Chomnunti et al. 2014) and cultured on potato dextrose agar (PDA). The Petri dishes were placed in an incubator and cultured at 25 °C under a 12-h photoperiod. Colonies were initially white with thin aerial mycelia and gradually turned dark grey with irregular margins. Conidiomata were acervular, black and scattered, with a diameter of 0.3 - 0.7 mm. Conidiophores were narrowly cylindrical, simple or branched at the base, 30 - 43 × 3 - 8 µm (x = 36.5 × 5.5 µm, n = 40). Conidiogenous cells were annellidic with distinct annellations. Conidia were unicellular, brown when mature, narrowly ellipsoid with gelatinous sheaths and truncate scars at the base, 17 - 32 × 7 - 12 µm (x = 27 × 9 µm, n = 40). The genomic DNA of a representative isolate SICAUCC 22-0064 was extracted, and the internal transcribed spacer (ITS) region, guanine nucleotide-binding protein subunit beta gene (ms204), translation elongation factor 1-alpha (tef1-α), and partial sequences of β-tubulin (tub2) were amplified by polymerase chain reaction and sequenced with primers V9G/LR5 (de Hoog & van den Ende 1998), MS-E1F1/MS-E5R1 (Walker et al. 2012), EF1-728F (Carbone & Kohn 1999)/TEF1LLErev (Jaklitsch et al. 2005), and T1/BtHV2r (Voglmayr et al. 2017), respectively. The sequences of ITS, ms204, tef1-α, and tub2 were deposited in NCBI with accession numbers ON000068, ON112376, ON112374, and ON112375, respectively. With the consideration of the sequence lack of ms204 and tub2 in the ex-type strain (D96) of Juglanconis appendiculata Voglmayr & Jaklitsch, the isolate D140 was used for nucleotide blast. The results showed 99.68%, 100%, 100%, and 100% identities of ITS, ms204, tef1-α, and tub2 with D140 (accession numbers KY427138, KY427157, KY427207, KY427226). Phylogenetic analysis based on a combined dataset showed 100% bootstrap with J. appendiculata, and the morphology was consistent with the asexual stage of J. appendiculata (Voglmayr et al., 2017). To verify Koch’s postulates, five branches wounded by pin-prick were sprayed with conidial suspension (1 × 105 conidia/mL) in each plant, and three repetitions were performed on healthy 2-year-old potted plants. The same number of branches were sprayed with sterile distilled water as controls. The plants were placed in a greenhouse at 25 ℃ under 90% relative humidity and a 12-h fluorescent light/dark regime. After five weeks, all the inoculated branches showed brown necrosis similar to that observed in the field, and no symptoms occurred on the controls. The pathogens were re-isolated from the necrotic lesions and identified by morphology and phylogeny. J. appendiculata has been reported on Juglans nigra and J. regia in Austria, France, Spain and Greece (Farr & Rossman 2022). This paper is the first report of branch blight on Juglans sigillata caused by J. appendiculata in China. This result may develop the understanding of walnut diseases and lay a foundation for further management.