Clubroot disease caused by the obligate parasite Plasmodiophora brassicae is a serious threat to cabbage production worldwide. Current clubroot control primarily relies on a fungicide, but this has a negative impact on the environment and the use of a single biocontrol agent cannot efficiently control the disease. Thus, the combined application of different biocontrol agents has been proposed as a promising alternative. In this study, we used bacterial biocontrol agents as a co-culture (inter-genus and intra-genus) and mono-culture to mitigate the clubroot disease of Chinese cabbage. We evaluated their biocontrol effect and plant growth promoter (PGP) traits in in vitro and in vivo experiments. This study revealed that the inter-genus bacterial co-culture significantly suppresses the incidence of clubroot disease and enhances plant growth compared with intra-genus and mono-culture. In pairwise interaction, we observed that Bacillus cereus BT-23 promotes the growth of Lysobacter antibioticus 13-6 (inter-genus bacterial co-culture), whereas L. capsici ZST1-2 and L. antibioticus 13-6 (intra-genus microbial co-culture) are antagonists to each other. Furthermore, a total of 5575 metabolites, 732 differentially expressed metabolites (DEMs), and 510 unique metabolites were detected through the LC-MS/MS technique in the bacterial co-culture. The number of unique metabolites in inter-genus bacterial co-culture (393 metabolites) was significantly higher than in the intra-genus bacterial co-culture (117 metabolites). Further analysis of DEMs showed that the DEMs were mainly involved in four kinds of metabolism pathways, i.e., carbohydrate metabolism, amino metabolism, nucleotide metabolism, and metabolism of cofactors and vitamins. The contents of some secondary metabolites with biocontrol activity and plant growth-promoting functions were increased in inter-genus bacterial co-culture, indicating that inter-genus bacterial co-culture has a solid potential to suppress clubroot disease. We conclude that the inter-genus bacterial interaction changes the community metabolism and improves several secondary metabolites functions with respect to disease control and PGP ability.

Lead (Pb) is a common contaminant that causes serious health and environmental problems. Thus, appropriate environmentally friendly and efficient techniques must be developed to remediate Pb in soils. Biochar (BC) has shown promise as an effective strategy to mitigate Pb toxicity. Trehalose (Tre) is a promising sugar that has been shown to effectively improve plant tolerance to abiotic stresses. Nonetheless, its role in alleviating Pb toxicity is unknown. The study investigated the impacts of BC and Tre co-application in alleviating Pb toxicity in rice crops. The study included the following treatments: control, Pb stress (250 mg kg⁻¹), Pb stress (250 mg kg⁻¹) + BC (2.5%), Pb stress (250 mg kg⁻¹) + Tre (30 mM), and Pb stress (250 mg kg⁻¹) + BC (2.5%) + Tre (30 mM). Results showed that Pb toxicity reduced rice yield by decreasing chlorophyll synthesis and relative water content (RWC), by increasing malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) contents, Pb accumulation in roots and shoots, soil available Pb concentration, and by decreasing the availability of soil nutrients. BC and Tre application mitigated the adverse impacts of Pb; however, more promising results were obtained with the co-application of BC and Tre. The results indicated that co-application of BC and Tre increased the rice yield by increasing photosynthetic pigments (46–96.42%), leaf water contents (16.67%), proline and soluble protein synthesis (35.13% and 24.96%), and antioxidant activities (12.07–31.67%), by decreasing root (59.72%), shoot (76.47%), and soil (57.14%) Pb concentrations, and the Pb translocation factor (15.08%). These findings suggested that co-application of BC and Tre can be a practical approach for reducing Pb toxicity, availability, and uptake, which improves rice productivity in Pb-polluted soil.

To play a role effectively, biocontrol fungi must fight against plant immune response and establish a symbiotic interaction with their host. After successfully colonizing the host plant, the biocontrol fungi may deliver beneficial effects related to plant health and resistance against phytopathogens. These fungi use a variety of tactics to bypass the host immune response, including the production of effector proteins, miRNA interference, manipulation of host defense mechanisms, and others. In this review article, we discussed these strategies of biocontrol fungi based on recent findings. These methods enable the fungi to escape the plant’s intrinsic immunity and finely adjust the plant’s defense signaling cascades. Additionally, we discussed the importance of the physical barrier in the form of host cell walls and elucidated how biocontrol fungi use a combination of mechanical and enzymatic tactics to overcome this obstacle. Given the evolving comprehensions from molecular biology, genomics, and ecology, this review article highlights the prospective for a holistic, interdisciplinary approach to improve our understanding of the biocontrol mechanism.

Leaf-blight disease caused by the Fusarium oxysporum is an emerging problem in Dendrobium chrysotoxum production in China. Symptoms of leaf blight were observed on seedlings of D. chrysotoxum cultivated in a nursery in Ruili City, Yunnan Province, China. In this study, we isolated the Fusarium sp. associated with leaf-blight disease of D. chrysotoxum from the diseased seedlings. A pathogenicity test was performed to fulfill Koch’s postulates to confirm the pathogenicity of isolated strains and identified using morphological and molecular techniques. The results revealed that all four isolated Fusarium sp. isolates (DHRL-01~04) produced typical blight symptoms followed by marginal necrosis of leaves on the D. chrysotoxum plants. On the PDA medium, the fungal colony appeared as a white to purplish color with cottony mycelium growth. Microconidia are oval-shaped, whereas macroconidia are sickle-shaped, tapering at both ends with 2–4 septations. The phylogenetic trees were construed based on internal transcribed spacer (ITS), translation elongation factor (EF-1α), and RNA polymerase subunit genes RPB1 and RPB2 genes, respectively, and blasted against the NCBI database for species confirmation. Based on the NCBI database’s blast results, the isolates showed that more than 99% identify with Fusarium oxysporum. To our knowledge, this is the first comprehensive report on the identification of Fusarium oxysporum as the causal agent of Dendrobium chrysotoxum leaf blight in Yunnan Province, China, based on morphological and molecular characteristics.

Termite-associated Ophiocordyceps species remain understudied despite the high diversity of the genus. Here we describe Ophiocordyceps minuta (holotype CXAC 0026) from termites (Termitidae, Macrotermitinae) collected in Yunnan, China. Phylogenetic analyses based on nrLSU (nuclear large subunit ribosomal RNA), tef1-α (translation elongation factor 1-alpha), and rpb2 (RNA polymerase II second largest subunit) sequences resolve this fungus as a distinct lineage. Notably, deep genetic divergence (65 bp in tef1-α) between the two ex-type strains of the allied O. fusiformis (BCC 93025 and BCC 93026) reveals cryptic diversity within that nominal species. Beyond the new species, a morphological assessment of termite-associated Ophiocordyceps indicates that perithecial immersion status, ascospore morphology, and conidial features are the most taxonomically valuable characters for this ecological group. These findings expand the known diversity in southwest China and underscore the importance of integrating phylogenetic data with key morphological traits for species delimitation in under-explored habitats.

Vespa soror, is an important resource insect that is widely distributed in China. However, there have been few reports on the genetic diversity of this species so far. We based our study on Cytochrome c Oxidase Subunit I (COI) gene as a molecular marker, to estimate the genetic diversity of V. soror. The length of the COI gene is 614 base pairs (bp), and a total of 26 haplotypes were obtained. Among these haplotypes, Hap_3 and Hap_13 are the dominant haplotypes. Overall, V. soror exhibits high genetic diversity, with a haplotype diversity (Hd) of 0.941 ± 0.010 and a nucleotide diversity (Pi) of 0.01068 ± 0.00079. Significant genetic differentiation has occurred among populations, with pairwise Fixation Index (Fst) values greater than 0.25 accounting for over two-thirds of all comparisons. The overall FST value was 0.47872. Despite fluctuations in the degree of genetic differentiation among different populations (−0.076 to 1.00), the overall level of genetic differentiation remained within a relatively high range. For most populations, the Tajima’s D and Fu’s Fs test results were positive, and both were non-significant (p > 0.10). AMOVA attributed 15.82%, 36.37%, and 47.81% of total variation to among-group, among-population within-group, and within-population variation, respectively. Overall, it exhibits high genetic diversity, significant genetic differentiation.