It is indicated that banana DMR6 functions as a negative regulator of plant immunity and is closely associated with susceptibility to Fusarium wilt, providing a molecular basis for future functional validation and support DMR6 as a potential target for precise genome editing to develop resistant banana cultivars.
Abstract
Fusarium wilt, caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense, remains the principal constraint on banana production, particularly for the widely cultivated cultivar ‘Prata-Ana’ (AAB) in Brazil. Given the limited efficacy of conventional control strategies, susceptibility (S) genes have emerged as promising targets for developing resistant cultivars. This study investigated the expression of the banana DMR6 gene during the interaction with Foc. DMR6 was selected because it is a conserved plant susceptibility gene that negatively regulates salicylic acid-mediated immunity, making it a promising target for genome editing. Banana plantlets were inoculated with Foc Subtropical Race 4 under controlled conditions. Temporal expression of the banana DMR6 gene was analyzed by RT-qPCR, and host defense responses were assessed by histochemical and microscopic analyses. DMR6 expression initially decreased and subsequently increased, reaching a 6.5-fold induction at 72 h post-inoculation relative to non-inoculated controls. This expression peak coincided with spore formation and advanced vascular colonization. Although infected roots exhibited callose deposition and phenolic compound accumulation, these defense responses were insufficient to restrict pathogen progression, resulting in severe disease symptoms and a disease severity index of 80% at 90 days after inoculation. The findings indicate that banana DMR6 functions as a negative regulator of plant immunity and is closely associated with susceptibility to Fusarium wilt. These results provide a molecular basis for future functional validation and support DMR6 as a potential target for precise genome editing to develop resistant banana cultivars.
Durum wheat is highly susceptible to Fusarium head blight (FHB) caused by the fungal pathogen Fusarium graminearum. Wheat can be protected with the use of environmentally-friendly and sustainable methods involving biological control agents (BCAs) such as yeasts. However, the mechanism underlying the antagonistic effects of yeasts on plant pathogens has not been fully elucidated. Therefore, the aim of this study was to expand the existing knowledge about the mechanisms of action of a Debaryomyces hansenii biopreparation through transcriptome profiling in F. graminearum cells using RNA sequencing (RNA-seq). The changes in the F. graminearum transcriptome resulting from biotic stress induced by the application of D. hansenii cells to durum wheat spikes, and abiotic stress induced by the application of a cell-free supernatant were compared and comprehensively analyzed. Each stressor elicited a completely different transcriptomic response, and differentially expressed genes (DEGs) encoding metabolic pathways essential for pathogen development associated with carbohydrate and amino acid metabolism, pathogenicity factors, effectors, and secondary metabolites. Numerous transporter genes were also identified, which indicates that fungi exhibit complex responses to biotic and abiotic stresses. The study demonstrated that F. graminearum uses various strategies to overcome the biotic stress associated with BCAs, including the upregulation of the brefeldin A resistance gene (FGSG_02870), which encodes an antifungal compound that inhibits the growth of BCA cells. The present findings provide novel insights into the interactions between pathogens and BCAs with specific mechanisms of action at the transcriptome level, thus helping to explain the relative ineffectiveness of BCAs under certain conditions.
Weronika Giedrojć, W. Pluskota, U. Wachowska· Fungal Genetics and Biology· 0 citations
Findings establish F. solani as a causal agent of durian stem rot in Hainan and highlight the potential of Bacillus-based biological control as a sustainable strategy for disease management in durian production systems.
Pathogenic strains of Fusarium oxysporum are major soilborne fungal pathogens responsible for Fusarium wilt in tomato, leading to significant yield losses worldwide. This study evaluated the biocontrol potential of rhizospheric bacterial isolates from argan (Argania spinosa) and raspberry (Rubus idaeus) soils through an integrated approach combining in vitro screening, greenhouse validation, and phylogenetic analysis. A total of 27 bacterial isolates were screened for antifungal activity using dual culture assays, of which ten exhibited more than 50% inhibition of fungal growth. Selected isolates were further evaluated for volatile organic compound (VOC)-mediated inhibition. Despite strong in vitro performance for several isolates, greenhouse experiments revealed that antifungal activity in vitro was not a reliable predictor of in planta efficacy. Among the tested isolates, BSA25, BSA23, and BSF8 significantly reduced disease severity and incidence under greenhouse conditions, with BSA25 achieving the greatest suppression. In addition to disease control, certain isolates promoted plant growth under pathogen stress, indicating dual functionality as plant growth-promoting rhizobacteria (PGPR). Molecular identification based on 16S rRNA gene sequencing and phylogenetic analysis (Neighbor-Joining, Kimura 2-parameter) revealed that the isolates belong to PGPR-associated genera, including Bacillus and Pseudomonas, while also highlighting functional variability among closely related taxa. Overall, this study demonstrates that multi-trait evaluation, integrating mechanistic screening and in planta validation, provides a more reliable framework for selecting effective biocontrol agents. The identified isolates, particularly BSA25, represent promising candidates for further evaluation for sustainable management of Fusarium wilt in tomato production systems.
Safouane Benjaa, R. Bouharroud, S. Chafiki et al.· International Journal of Pla...· 0 citations
Sclerotinia sclerotiorum, the causal agent of white mold, is a globally distributed fungal pathogen responsible for major yield losses in many crops. Spray-induced gene silencing (SIGS) has emerged as a promising alternative for disease control. Building on prior research, this study advanced SIGS by targeting S. sclerotiorum argonaute 2 (SsAgo2), using FF4 (PAZ domain to 5'-PIWI domain) and FF5 (PIWI central domain) fragments which are important regions involved in RNA binding and cleavage. We optimized spray tank mix/dilution in the greenhouse and scaled up dsRNA production using E. coli. The greenhouse results demonstrated that dsRNA with nanosheets significantly inhibited white mold disease on tomato and N. benthamiana compared to empty vector control (p = 0.03 and 0.004, respectively). To evaluate off-target effects, SIGS was tested on Botrytis cinerea, a related necrotrophic pathogen. No significant differences in lesion size were observed between SsAgo2 dsRNA-treated and water-treated Nicotiana benthamiana leaves. Gene ontology analysis of differential expressions in sunflower leaves revealed no significant differences between SsAgo2-FF4 or SsAgo2-FF5 compared to control. Field trials in 2024 demonstrated effectiveness. Parameters assessed included disease severity, wet weight, head width, and seed weight. Area under the disease progress curve (AUDPC) analysis revealed that dsRNA sprays, applied before and after manual inoculation or during natural infection, significantly reduced infection levels with p < 0.1 as the cut off. Sunflower fresh weight increased by 104.4 g (p = 0.04) and 96.7 g (p = 0.07), while head width increased by 2.5 cm (p = 0.03) and 1.5 cm (p = 0.10), respectively. This report demonstrates that the dsRNA mixture has potential to incorporate SIGS into field applications for the management of white mold disease.
Tseng Yi-Wen, C. Pedersen, Zhi-Yuan Chen et al.· Plant Disease· 0 citations
Plant gray mold disease, caused by the necrotrophic fungus Botrytis cinerea, threatens global food security by infecting over 1,400 species. The resistance of B. cinerea to fungicides poses a major challenge for its control. RNA interference (RNAi) shows promise for pathogen management, but high production costs, poor stability, and inefficient delivery of double-stranded RNA (dsRNA) restrict its practical use. In this study, we developed Yarrowia lipolytica strain MP181-2 as a novel RNAi platform, leveraging its ability to colonize the phyllosphere of crop plants (tomato and alfalfa) to enable simultaneous dsRNA production and pathogen targeting via microbe-induced gene silencing (MIGS). Through target screening, we identified three essential fungal genes, BcRpd3, BcNat1, and BcArd1, whose silencing significantly reduced the pathogenicity of B. cinerea. We further constructed a chimeric dsRNA molecule (BcANR-dsRNA) targeting these three genes, which demonstrated superior disease suppression compared to single-gene targeting. The engineered Y. lipolytica strains that produce dsRNA could effectively interfere with the expression of target genes in B. cinerea, and the strain expressing BcANR-dsRNA (designated Yl-dsANR) acquired the ability to suppress the growth of B. cinerea. In planta tests confirmed that Yl-dsANR successfully interfered with the expression of three target genes, leading to decreased fungal biomass and reduced lesion development on different hosts. Notably, foliar application of Yl-dsANR provided durable protection (over 70% efficacy for 5 d) in potted plants. Our integrated approach combines the advantages of microbial biocontrol with RNAi precision, establishing Y. lipolytica as a versatile chassis for sustainable crop protection. This study also provides an effective solution to current limitations in RNA pesticide development and offers a scalable, eco-friendly alternative to chemical fungicides for gray mold management.
Mengjie Liu, Hengshui Shen, Jie Li et al.· Journal of Integrative Plant...· 0 citations
Fusarium wilt of banana threatens banana production world-wide. Although beneficial rhizomicrobiomes are linked to disease resistance, whether resistant cultivars systemically recruit disease-suppressive rhizomicrobiomes after pathogen challenge remains unclear. Using a split-root system combined with rhizomicrobiome transfer, we tested whether systemically recruited rhizomicrobiomes from different cultivars after pathogen challenge could alter disease development in a susceptible cultivar. Rhizosphere soil suspension from the pathogen-challenged highly resistant cultivar GCTCV119 was the only donor treatment that significantly reduced the disease index in the susceptible recipient cultivar Guijiao No. 1. This effect was associated with pathogen-induced enrichment of absolute bacterial abundance and absolute Bacillus abundance in the rhizosphere of GCTCV119, whereas such enrichment was not observed in the other donor cultivars. A syncom of seven Bacillus strains from the GCTCV119 rhizosphere most effectively reduced (by 90.20%) the disease index by the induction of plant resistance. Soil incubation showed that pathogen-induced D-sorbitol accumulation in GCTCV119 significantly increased total bacterial abundance and Bacillus abundance, and reduced the disease index. This study highlights pathogen-triggered rhizomicrobiome reshaping, higher absolute bacterial abundance, and the suppressive role of Bacillus as key features linked to disease resistance in banana, providing insights into microbiome-mediated disease suppression.
Wenlong Zhang, Shengtao Xu, Hongwei Yu et al.· New Phytologist· 0 citations
