Stagonosporopsis pogostemonis: A Novel Ascomycete Fungus Causing Leaf Spot and Stem Blight on Pogostemon cablin (Lamiaceae) in South China

Trichoderma koningiopsis Tk905: an efficient biocontrol, induced resistance agent against banana Fusarium wilt disease and a potential plant-growth-promoting fungus

Fusarium oxysporum f. sp. cubense tropical race 4 (FocTR4) is a devastating phytopathogen responsible for significant losses in banana production worldwide. Trichoderma and other biocontrol agents (BCAs) have been used as suitable disease control methods for banana Fusarium wilt. In this study, the endophytic T. koningiopsis Tk905 strain was isolated from the roots of dendrobe plants and identified utilizing morphological and molecular analyses. Antifungal activity tests revealed that Tk905 effectively inhibited mycelial growth with inhibition rates ranging from 26.52 to 75.34%. Additionally, Tk905 covered the pathogen mycelia, and spores were observed on or around the pathogen hyphae. The average root and shoot fresh weights and plant height, of Tk905-inoculated plants were significantly higher than those of the untreated plants. Furthermore, Tk905 treatment significantly increased the activity of antioxidant enzymes, such as catalase (CAT), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD), suggesting that Tk905 may enhance plant defence systems by activating their antioxidant mechanisms. Most importantly, Tk905-treated plants inoculated by three methods exhibited significantly lower disease incidence and severity than untreated plants. The protective effects of Tk905 against FocTR4 infection were not only observed in the early stages of infection but persisted throughout the experiment, suggesting that T. koningiopsis Tk905 can provide long-lasting protection against Fusarium wilt.

Combination of Aspergillus niger MJ1 with Pseudomonas stutzeri DSM4166 or mutant Pseudomonas fluorescens CHA0-nif improved crop quality, soil properties, and microbial communities in barrier soil

Soil salinization and acidification seriously damage soil health and restricts the sustainable development of planting. Excessive application of chemical fertilizer and other reasons will lead to soil acidification and salinization. This study focus on acid and salinized soil, investigated the effect of phosphate-solubilizing bacteria, Aspergillus niger MJ1 combined with nitrogen-fixing bacteria Pseudomonas stutzeri DSM4166 or mutant Pseudomonas fluorescens CHA0-nif on crop quality, soil physicochemical properties, and microbial communities. A total of 5 treatments were set: regular fertilization (T1), regular fertilization with MJ1 and DSM4166 (T2), regular fertilization with MJ1 and CHA0-nif (T3), 30%-reducing fertilization with MJ1 and DSM4166 (T4), and 30%-reducing fertilization with MJ1 and CHA0-nif (T5). It was found that the soil properties (OM, HN, TN, AP, AK, and SS) and crop quality of cucumber (yield production, protein, and vitamin C) and lettuce (yield production, vitamin C, nitrate, soluble protein, and crude fiber) showed a significant response to the inoculated strains. The combination of MJ1 with DSM4166 or CHA0-nif influenced the diversity and richness of bacterial community in the lettuce-grown soil. The organismal system-, cellular process-, and metabolism-correlated bacteria and saprophytic fungi were enriched, which were speculated to mediate the response to inoculated strains. pH, OM, HN, and TN were identified to be the major factors correlated with the soil microbial community. The inoculation of MJ1 with DSM4166 and CHA0-nif could meet the requirement of lettuce and cucumber growth after reducing fertilization in acid and salinized soil, which provides a novel candidate for the eco-friendly technique to meet the carbon-neutral topic.

Plant-Associated Novel Didymellaceous Taxa in the South China Botanical Garden (Guangzhou, China)

The South China Botanical Garden (SCBG), one of the largest and oldest botanical gardens in China, conserves important plant germplasms of endangered species. Therefore, ensuring tree health and studying the associated mycobiome of the phyllosphere is essential to maintaining its visual aesthetics. During a survey of plant-associated microfungal species in SCBG, we collected several coelomycetous taxa. Phylogenetic relationships were evaluated based on the analyses of ITS, LSU, RPB2, and β-tubulin loci. The morphological features of the new collections were compared with those of existing species, emphasizing close phylogenetic affinities. Based on the morphological comparisons and multi-locus phylogeny, we introduce three new species. These are Ectophoma phoenicis sp. nov., Remotididymella fici-microcarpae sp. nov., and Stagonosporopsis pedicularis-striatae sp. nov. In addition, we describe a new host record for Allophoma tropica in the Didymellaceae. Detailed descriptions and illustrations are provided along with notes comparing allied species.

First Record of Alternaria pogostemonis: A Novel Species Causing Leaf Spots in Pogostemon cablin

Pogostemon cablin (Lamiaceae) is a component of traditional medicines in Southern China. The identification of P. cablin pathogens is essential for the production and development of this industry. During 2019–2020, a leaf spot on P. cablin was observed in Zhanjiang, Guangdong Province. The pathogen of the leaf spot was isolated and identified using morphological and phylogenetic methods. Phylogenetic analysis was performed using the internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (gapdh), RNA polymerase II (rpb2), translation extension factor 1-alpha (tef1), and Alternaria major allergen 1 (Alt-a1) genes. Based on phylogenetic and morphological studies, this was confirmed to be a novel species of Alternaria pogostemonis, with description and illustrations presented. The pathogenicity test of A. pogostemon was verified by Koch’s postulates as causing leaf spot disease. This is the first report of leaf spot disease in P. cablin caused by the Alternaria species. This study contributes to the knowledge of P. cablin leaf spot diseases.

Lasiodiplodia fici sp. nov., Causing Leaf Spot on Ficus altissima in China

High temperatures and the seasonality in tropical ecosystems favours plant pathogens, which result in many fungal diseases. Among these, diseases caused by Botryosphaeriaceae species are prominent as dieback, canker and leaf spots. In this research, we isolated one leaf-spot-causing Botryosphaeriaceae species from Ficus altissima leaves, which were collected in Guangzhou, Guangdong Province, China. Isolation and identification of the pathogen were based on morphological and molecular aspects. Based on multigene phylogenetic analysis of combined internal transcribed spacer (ITS), translation elongation factor 1-α gene (tef1) and beta-tubulin gene (tub2), the fungus associated with leaf spots on F. altissima is described as Lasiodiplodia fici, a novel species. Pathogenicity assays were conducted by inoculating the fungus onto detached shoots and plants under controlled environmental conditions. The results revealed that the L. fici isolates can infect the plant tissues under stress conditions by developing disease symptoms on detached shoots within three days. However, when it was inoculated onto the leaves of the host and grown in natural conditions, the progression of the disease was slow. The putative pathogen was re-isolated, and Koch's assumptions were satisfied. This is the first report of Lasiodiplodia species causing disease on Ficus altissima. Results from the present study will provide additional knowledge on fungal pathogens associated with forest and ornamental plant species.