Dollar spot, caused by fungi in the Clarireedia genus, is among the most economically important turfgrass diseases. One strategy for controlling dollar spot is the use of tolerant cultivars, which typically take longer to develop symptoms and have smaller lesion centers compared with more susceptible cultivars. We previously developed a quantitative PCR (qPCR) assay that can quantify the Clarireedia concentration in asymptomatic and symptomatic turfgrass. The goal of this 3-year study was to quantify the concentration of Clarireedia in a tolerant and susceptible cultivar of creeping bentgrass (Agrostis stolonifera) throughout the growing season to determine the effect host tolerance has on dollar spot development in the field. Turfgrass samples were collected weekly in 2019, 2020, and 2021 starting the first week of May and ending the second week of August for a duration of 15 weeks each year. The qPCR assay identified significant differences in Clarireedia concentration between the cultivars in both asymptomatic and symptomatic tissue. Linear model analysis showed the tolerant cultivar Declaration always had a lower Clarireedia concentration compared with the susceptible cultivar Independence. This supported our inhibition hypothesis that, although the concentration of Clarireedia required to cause symptoms was similar for both cultivars, the pathogen increased at a slower rate and therefore took longer to develop in a tolerant cultivar. The ability of the qPCR assay to quantify the concentration of Clarireedia in both asymptomatic and symptomatic tissue in the field during the growing season provides a tool for more in-depth epidemiological studies of dollar spot disease in turfgrass.

Drought stress severely limits maize productivity. Although plant growth-promoting rhizobacteria (PGPR) including Bacillus velezensis, are known to enhance drought tolerance, the underlying molecular mechanisms and essential host genes remain poorly defined. In this study, we demonstrate that B. velezensis D103 enhances maize drought tolerance through a coordinated physiological and molecular mechanism that preserves photosynthetic function and redirects carbon metabolism toward roots. Physiological analyses demonstrated that D103 inoculation improved photosynthetic performance and promoted root accumulation of carbohydrate under drought stress. Transcriptomic profiling revealed concurrent modulation of genes associated with photosynthesis and carbon metabolic pathways. Functional validation using virus-induced gene silencing (VIGS), we identified two distinct classes of host genes. Silencing of key non-compensable genes (ZmPsbXL, ZmSWEET13b, ZmPLT5, ZmGALX, and ZmFAB1D) eliminated the beneficial effects of D103, whereas drought tolerance was maintained in plants silenced for functionally compensable genes (ZmSWEET14, ZmRFS1, ZmBANGLUC) through activation of related paralogs, revealing a structured genetic network that confers functional resilience. Together, these findings establish a causal, gene-level framework for PGPR-mediated drought tolerance and highlight B. velezensis D103 as a promising microbial biostimulant for improving crop resilience to water limitation.

Native laccase production in polymorphic black yeasts is often limited by unstable cellular differentiation and insufficient metabolic coordination. Here, we developed a glucose-glycerol cofermentation strategy to improve laccase production in Aureobasidium melanogenum ZN by regulating cellular morphology and metabolism. The results showed that glycerol stabilized yeast-like growth and suppressed melanized differentiation, while the optimized combination of 2% glucose and 7.5% glycerol increased laccase activity and yield to 418.43 U·mL-1 and 65.67 U·g-1 dry weight (DW), respectively. The crude laccase showed an optimal activity at 75 °C and efficiently decolorized triphenylmethane dyes, especially malachite green, with partial activity retained under NaCl-containing and simulated wastewater-like conditions. Physiological and multiomics analyses linked glycerol-enhanced laccase production to yeast-like-state maintenance, carbon-source regulation, respiratory metabolism, redox adjustment, antioxidant responses, and reduced melanized differentiation. This study provides a morphology-metabolism-directed strategy for enhancing laccase production in native polymorphic fungi.

Pleoscrubia floridana, sp. nov. included in Pleoscrubia, gen. nov. isolated from roots of the Florida endemic Paronychia chartacea (paper nailwort; Caryophyllaceae), is described. Multigene phylogenetic analyses suggest that the fungus represents a novel lineage and along with morphological and ecological characteristics support the description of Pleoscrubiaceae, fam. nov. within Pleosporales (Dothideomycetes) to accommodate this distinct genus and species. Pleoscrubia floridana is likely unique to the Florida scrub ecosystem and associated with Paronychia chartacea host. The plant-fungal interaction experiment yielded neutral results on Arabidopsis thaliana. This newly discovered fungal lineage will help researchers understand the diversity and systematics of Pleosporales.

During a survey of plant root-associated microbiota in the Pennsylvania Chrome Serpentine Barrens, we identified two previously unrecognized fungal lineages from Panicum virgatum (switchgrass). Based on multigene phylogenetic analyses, along with morphological and ecological characterization, we propose the establishment of two new genera, Curvophialophora and Drepanoconia, together with their respective species, Curvophialophora panicicola, sp. nov. and Drepanoconia panicicola, sp. nov. in the family Magnaporthaceae. Curvophialophora is characterized by simple, undifferentiated, septate, hyaline conidiophores bearing terminal, strongly curved phialidic conidiogenous cells that produce aseptate, hyaline, ovoid to ellipsoidal conidia. Drepanoconia has complex, differentiated, straight, brown conidiophores with terminal, slightly curved phialidic conidiogenous cells producing aseptate, hyaline, strongly curved sickle-shaped conidia. The plant-fungal interaction experiment showed that both genera had significant inhibitory effects on Arabidopsis thaliana, indicating their phytotoxicity potential on plants. These findings expand our knowledge on the microbiota associated with switchgrass, an emerging biofuel crop, and contribute to the study of systematics, diversity, and function of Magnaporthaceae.

Dollar spot is a foliar blight of turfgrasses caused by Clarireedia species. An existing quantitative polymerase chain reaction (qPCR) protocol was shown to quantify the abundance of Clarireedia from both asymptomatic and symptomatic tissues, which makes it a useful tool for monitoring the pathogen in the field. The qPCR assay uses a tiny amount of tissue, so generating an accurate representative sample from a large turfgrass sward is necessary. The main objective of this study was to determine the best sampling method for qPCR analysis for accurate detection and quantification of Clarireedia in creeping bentgrass (Agrostis stolonifera) fields. Two dollar spot-susceptible cultivars of creeping bentgrass, 'Crenshaw' (2020) and 'Independence' (2021), were used in the study. Symptomatic and asymptomatic samples were collected each year from 12 replicated 0.91 m & times; 1.52 m plots maintained at a 9.5 mm (bench set) cutting height. Average cycle threshold (Ct) values were determined using the qPCR assay from: (1) 10 individual cores measuring 1 cm & times; 2.5 cm deep, evaluated as subsamples; (2) composites of 10 cores of 1 cm & times; 2.5 cm deep; and (3) tissue obtained by vertical mowing at two heights (4.8 or 7.1 mm bench set). Overall, vertical mowing was found to be the best sampling method for quantifying Clarireedia in foliage. Vertical mowing sampled 2.62% of each plot compared with only 0.23% for cores and composites, had the lowest variability in Ct values, consistently identified plots containing asymptomatic and symptomatic tissue, and represents a sampling method that could be easily adopted by golf course superintendents to monitor the population of Clarireedia to schedule fungicide applications and potentially reduce fungicide inputs.

Black yeast-like fungi of the genus Aureobasidium exhibit morphological plasticity, but whether distinct cellular states within the same genetic background are associated with different plant growth-promoting functions remains unclear. Here, yeast-like cells (YL), swollen cells (SC), and chlamydospores (CH) of Aureobasidium melanogenum ZN were characterized. YL was associated mainly with siderophore production and laccase activity, SC with extracellular polysaccharide accumulation, and CH with phosphate mobilization and higher ammonia and IAA production. Whole-genome and comparative genomic analyses revealed a shared repertoire related to nutrient acquisition, auxin-associated metabolism, extracellular oxidation, and carbohydrate remodeling, with expansions in nutrient- and cell-surface-related gene families. Transcriptomic and metabolomic analyses showed distinct deployment of these capacities, with CH exhibiting broad reprogramming of tryptophan-associated, nitrogen, phosphate, central-carbon, and amino-acid metabolism. In maize, CH at the optimal inoculation concentration of 105 CFU·mL-1 produced the strongest growth promotion, increasing plant height, dry biomass, root length, root surface area, and root volume by 58.6%, 365.1%, 191.0%, 194.3%, and 222.4%, respectively. Consistent with this pronounced growth phenotype, maize root transcriptomics showed coordinated CH-induced responses involving root development, nutrient transport, redox regulation, and root-interface remodeling. Root-zone tracking showed greater short-term stability and persistence of CH. These findings identify cellular state as an important functional dimension of Aureobasidium-plant interactions and provide a basis for developing fungal inoculants with defined beneficial cellular states.

Carotenoids are natural pigments with vibrant colors and bioactivities, widely used in food, pharmaceutical, and cosmetic industries. Rhodosporidiobolus odoratus, an oleaginous red yeast, produces high-value carotenoids, including β-carotene, torulene, and torularhodin. This study investigated the impact of initial H2O2 additions (5, 10, 20, 30, 40, and 50 mM) on carotenoid production in R. odoratus XQR. Treatment with moderate H2O2 (20 mM) for 120 h maximized carotenoid production at 66.03 μg/g (1.59-fold the control), with respective changes in β-carotene (1.67-fold), torulene (0.72-fold), and torularhodin (3.52-fold). Integrated multiomics analyses suggest that enhanced carotenogenesis likely results from coordinated upregulation of mevalonate pathway genes (HMGCS, hmgA, mvaK2, and mvaD) and dedicated carotenogenic genes (crtYB, crtI, crtZ, and crtA) together with downregulation of lipogenesis and β-carotene-derived apocarotenoids, implicating precursor reallocation and attenuation of apocarotenoid volatiles as synergistic mechanisms. The findings elucidate H2O2-mediated regulation of carotenogenesis in this yeast, providing metabolic engineering targets for yield improvement.

Bacillus velezensis D103 improves drought tolerance through enhanced antioxidant activity and lignin deposition, with VIGS analysis indicating roles for ZmAPX3, ZmAOX1B, ZmPER72, and ZmPRX74. Drought stress is a major abiotic constrain on global crop productivity. The application of plant growth-promoting rhizobacteria (PGPR) offers a promising strategy to enhance plant drought tolerance, yet the associated molecular mechanisms remain incompletely characterized. In this study, we examined the role of Bacillus velezensis D103 in maize drought responses by assessing physiological and transcriptomic changes. Under drought stress, D103 inoculation supported plant growth and increased leaf relative water content (RWC), reducing the RWC deficit from 12.4

Ophiorrhiza guizhouensis has not had its complete chloroplast genome reported, which limits our understanding of its genetics and evolution. In this study, we assembled and annotated its chloroplast genome, revealing a circular structure with 80 protein-coding genes (GenBank accession number: PX023271). The total length of the genome was found to be 154,134 bp, and its GC content was 37.76%. Phylogenetic analysis confirmed that Ophiorrhiza guizhouensis belonged to the genus Ophiorrhiza (subfamily Rubioideae, Rubiaceae) and exhibited the closest phylogenetic affinity to Ophiorrhiza densa. These findings provide valuable genomic resources for in-depth studies on Ophiorrhiza and the Rubiaceae family, including genetic diversity analysis and phylogenetic research.

Volatile organic compounds (VOCs) from plant growth-promoting rhizobacteria (PGPR) regulate crop growth, but their dose-dependent effects in woody perennials are poorly understood. This study defined the dose–response relationships of VOCs from three PGPR strains (Pantoea ananatis D1-28, Burkholderia sp. D4-24, Burkholderia territorii D4-36) in apple. The optimal concentrations were 104, 106, and 105 CFU·mL−1, with D1-28 exerting the strongest effect, increasing plant height, biomass, and root volume by up to 75

Carotenoids are bioactive pigments widely used in food, pharmaceutical, and cosmetic industries. Rhodosporidiobolus odoratus co-produces commercially significant carotenoids, including β-carotene, torulene, and torularhodin. This study aimed to reveal how carotenoid biosynthesis in R. odoratus XQR, optimally grown at 20 °C, responds to low (10 °C) and high (30 °C) temperatures. After five days, total carotenoids reached 118.55 μg/g DCW and 0.40 μg/mL at 30 °C, ∼3-fold higher than the 20 °C control (41.25 μg/g DCW and 0.14 μg/mL). Torularhodin showed a pronounced increase at 30 °C (37.26 μg/g DCW and 0.12 μg/mL), ∼9-fold above the control (4.06 μg/g DCW and 0.014 μg/mL). At 10 °C, total carotenoids declined to 26.09 μg/g DCW, with a slight, non-significant rise in volumetric titer to 0.17 μg/mL. High temperature elevated reactive oxygen species (ROS) and superoxide dismutase (SOD) activity while reducing total protein, whereas low temperature maintained stable ROS, induced moderate SOD, and caused protein decline; catalase (CAT) activity changed minimally under both conditions. Our integrated data suggest that high temperature promotes carotenoid overaccumulation through upregulation of key terpenoid backbone biosynthetic genes (HMGCS, hmgA, and mvaD) and carotenogenic genes (crtYB, crtI, crtZ, and crtA), coupled with a metabolic shift that enhanced precursor supply. These coordinated responses explain torularhodin-dominant accumulation and differ from related yeasts, suggesting species-specific regulation. This work provides new mechanistic insights into temperature-driven carotenogenesis in R. odoratus XQR and highlights targets for metabolic engineering.

While plant growth-promoting rhizobacteria (PGPR) consortia show enhanced benefits over single strains, the systematic design of functionally complementary synthetic communities and their synergistic mechanisms through biofilm-mediated root colonization remain poorly explored. This study aimed to screen and construct functionally complementary PGPR consortia, systematically evaluate their synergistic effects on biofilm formation in the tomato rhizosphere, and elucidate the underlying mechanisms regulating plant growth through enhanced root colonization and metabolic interactions. Three PGPR strains -Pantoea ananatis D1-28, Bacillus aryabhattai LAD, and Burkholderia cepacia 4-5-were selected for individual and combinatorial inoculation experiments. The results demonstrated that the D1-28/LAD combination exhibited significant synergistic advantages in both biofilm formation and plant growth promotion. This consortium markedly enhanced rhizosphere colonization and the synthesis of growth-promoting factors (such as N, P, siderophores, and IAA), thereby significantly improving tomato growth and up-regulating auxin biosynthesis and nitrogen transporter gene expression in roots. At an inoculum concentration of 10(6) cfu.mL(-1), the fresh and dry weights of tomato shoots increased by 186.40 % and 278.57 %, respectively, while root fresh and dry weights increased by 327.62 % and 543.68 %. Plant height, root length, root surface area, and root volume increased by 117.19 %, 207.29 %, 531.36 %, and 525.69 %, respectively. This study provides theoretical insights into the role of microbial interactions in plant growth promotion and lays a technical foundation for the development of efficient and stable microbial biofertilizers, with promising applications in sustainable agriculture.

Sweet cherry (Prunus avium L.), as a high-economic-value fruit with both nutritional and health functions, faces severely constrained plant growth due to underdeveloped root systems and suboptimal orchard site conditions. Plant growth-promoting rhizobacteria (PGPR) demonstrate application potential in regulating plant development and improving soil structure through the release of volatile organic compounds (VOCs). This study systematically evaluated the effects of VOCs from three PGPR strains—Pantoea ananatis D1-28, Burkholderia sp. D4-24, and Burkholderia territorii D4-36—on cherry root development and rhizosphere microbial communities. The results indicate that when D1-28 and D4-24 strains were at 103 cfu·mL−1 and D4-36 was at 105 CFU·mL−1, their VOCs exhibited optimal growth-promoting effects. Compared with the control group, significant improvements were observed in cherry seedling parameters, including plant height, total biomass, root length, root surface area, and root volume. The VOCs from these strains synergistically promoted plant growth by regulating auxin synthesis pathways in cherry roots while enhancing the relative abundance of beneficial rhizosphere microorganisms. This study establishes the strain-concentration–effect relationship, providing a theoretical foundation to optimize soil microbial environments and promote cherry root development using PGPR.

Tomato (Solanum lycopersicum), a vital global crop rich in bioactive compounds, faces sustainability issues due to agrochemical overuse, necessitating eco-friendly biofertilizers like plant growth-promoting rhizobacteria (PGPR) for sustainable agriculture. This study aimed to identify superior PGPR strains with growth-enhancing volatile organic compounds (VOCs), characterize their VOC profiles, determine optimal VOC doses for growth promotion, and investigate their effects on root architecture, rhizosphere microbiome, and plant transcriptomics to elucidate mechanisms. Thirteen PGPR strains were screened for VOC-mediated tomato growth promotion. Key strains' VOCs were profiled using GC–MS. Dose-response assays tested core VOCs on growth and root architecture. Rhizosphere microbiome functional compartmentalization was analyzed, and transcriptomic profiling (KEGG pathway enrichment) of VOC-treated plants was performed. Three superior isolates (Pantoea ananatis D1-28, Burkholderia sp. D4-24, Burkholderia territorii D4-36) were identified, with D1-28 notably enhancing lateral roots and shoot biomass. GC–MS revealed strain-specific VOC profiles (31–37 compounds) sharing three core components: dimethyl disulfide (D), 2-nonanone (N), benzothiazole (B). Optimal doses profoundly remodeled root architecture and maximized growth: D (10⁻3 mmol/L), N (1 mmol/L), B (10⁻2 mmol/L). VOCs drove rhizosphere functional compartmentalization, enriching specific taxa. Transcriptomics identified 132 differentially enriched KEGG pathways (130 conserved), primarily linked to auxin biosynthesis, sulfur/nitrogen metabolism, energy metabolism, and carbohydrate metabolism, indicating analogous mechanisms. This study elucidates for the first time how P. ananatis VOCs coordinate plant hormone signaling, metabolic networks, and rhizosphere microecology to synergistically enhance tomato growth, providing a theoretical foundation for VOC-based green agricultural technologies.

Sporobolomyces pararoseus is a well-studied oleaginous red yeast that can synthesize a variety of high value-added bioactive compounds. Biofilm is one of the important biological barriers for microbial cells to resist environmental stresses and maintain stable fermentation process. Here, the effect of acidic conditions on the biosynthesis of biofilms in S. pararoseus NGR was investigated through the combination of morphology, biochemistry, and multi-omics approaches. The results showed that the acidic environment was the key factor to trigger the biofilm formation of S. pararoseus NGR. When S. pararoseus NGR was cultured under pH 4.7, the colony morphology was wrinkled, the cells were wrapped by a large amount of extracellular matrix, and the hydrophobicity and anti-oxidative stress ability were significantly improved, and the yield of intracellular carotenoids was significantly increased. Transcriptome and metabolome profiling indicated that carbohydrate metabolism, amino acid metabolism, lipid metabolism, and nucleic acid metabolism in S. pararoseus NGR cells were significantly enriched in biofilm cells under pH 4.7 culture conditions, including 56 differentially expressed genes and 341 differential metabolites. These differential genes and metabolites may play an important role in the formation of biofilms by S. pararoseus NGR in response to acidic stress. The results will provide strategies for the development and utilization of beneficial microbial biofilms, and provide theoretical support for the industrial fermentation production of microorganisms to improve their resistance and maintain stable growth.

The complete mitochondrial genome of Ophiorrhiza guizhouensis has not previously been reported, hindering insights into its genetic makeup and evolutionary history. In this study, we assembled and annotated this genome, revealing a single loop structure containing 36 protein-coding genes (GenBank accession number: PX058827). The total length of the genome was found to be 476,177 bp, and its GC content was 43.55%. Phylogenetic analysis based on mitochondrial genes indicated that Ophiorrhiza guizhouensis shared close evolutionary relationships with Psychotria viridis, Psychotria serpens, and Damnacanthus indicus.

Drought stress severely constrains crop productivity, and while plant growth-promoting rhizobacteria (PGPR) are known to enhance drought tolerance by modulating host aquaporins (AQPs), the specific role of bacterial biofilm formation in this regulatory process remains poorly understood. Here, we demonstrate that biofilm formation is a pivotal mechanism through which Bacillus velezensis D103 confers drought resilience to maize. Under drought stress, maize root exudates synergistically enhanced D103 biofilm formation, which was essential for robust root colonization and mediated a drought-adaptive restructuring of the rhizosphere microbiome. Crucially, we found that an intact bacterial biofilm systemically upregulated key plant AQPs (ZmPIP2;6 and ZmTIP1;1), thereby enhancing root water transport capacity. Using virus-induced gene silencing, we further clarified the molecular mechanism underlying this biofilm-aquaporin link, revealing that ZmPIP2;6 is indispensable for D103-conferred drought tolerance. Our findings refine the current understanding of PGPR-mediated drought tolerance, highlighting that biofilms coordinate host AQP expression, rhizosphere microbiome assembly, and soil water retention to enhance drought resilience. This work provides a mechanistic basis for developing effective microbial inoculants.