Pathogen profile update: Fusarium oxysporum

Fusaric acid mediates the assembly of disease-suppressive rhizosphere microbiota via induced shifts in plant root exudates

The plant health status is determined by the interplay of plant-pathogen-microbiota in the rhizosphere. Here, we investigate this tripartite system focusing on the pathogen Fusarium oxysporum f. sp. lycopersici (FOL) and tomato plants as a model system. First, we explore differences in tomato genotype resistance to FOL potentially associated with the differential recruitment of plant-protective rhizosphere taxa. Second, we show the production of fusaric acid by FOL to trigger systemic changes in the rhizosphere microbiota. Specifically, we show this molecule to have opposite effects on the recruitment of rhizosphere disease-suppressive taxa in the resistant and susceptible genotypes. Last, we elucidate that FOL and fusaric acid induce changes in the tomato root exudation with direct effects on the recruitment of specific disease-suppressive taxa. Our study unravels a mechanism mediating plant rhizosphere assembly and disease suppression by integrating plant physiological responses to microbial-mediated mechanisms in the rhizosphere.

Bioaerosol emissions from wastewater treatment process at urban environment and potential health impacts

The inlet of wastewater treatment plants (WWTPs) contains pathogenic microorganisms which during aeration and by mechanical mixing through wind typically aerosolized microbes into ambient air. Bioaerosol emission and its characterization (bacterial and fungal) was investigated considering low-flow and high-flow inlet of wastewater treatment plant. Generation of bioaerosols was found influenced by prevailing seasons while both during summer and winter, fungal concentration (winter: 1406 ± 517; summer: 1743 ± 271 CFU/m3) was higher compared to bacterial concentration (winter: 1077 ± 460; summer: 1415 ± 588 CFU/m3). Bioaerosols produced from WWTPs were predominately in the size range of 2.1-4.7 μm while fraction of fungal bioaerosols were also in ultra-fine range (0.65 μm). Bioaerosols reaching to the air from WWTPs varied seasonally and was calculated by aerosolization ratio. During summer, aerosolization of the bioaerosols was nearly 6 times higher than winter. To constitute potential health effects from the exposure to these bioaerosols, biological characterization, antibiotics resistance and the health survey of the nearby area were also performed. The biological characterization of the bioaerosols samples were done through metagenomic approach using 16s and ITS metagenomic sequencing. Presence of 167 genus of bacteria and 41 genus of fungi has been found. Out of this, bacillus (73%), curtobacterium (21%), pseudomonas, Exiguo bacterium, Acinetobacter bacillaceae, Enterobacteriaceae and Prevotella were the dominant genus (top 10) of bacteria. In case of fungi, xylariales (49%), Hypocreales (19%), Coperinopsis (9%), Alternaria (8%), Fusarium (6%), Biopolaris, Epicoccum, Pleosporaceae, Cladosporium and Nectriaceae were dominant. Antibiotics like, Azithromycin and cefixime were tested on the most dominant bacillus showed resistance on higher concentration of cefixime and lower concentration of azithromycin. Population-based health survey in WWTP nearby areas (50-150 m periphery) found several types of diseases/symptoms including respiratory problem, skin rash/irritation, change in smell and taste, eye irritation within the resident population and workers.

The differential virulence of Fusarium strains causing corneal infections and plant diseases is associated with accessory chromosome composition

Fusarium oxysporum is a cross-kingdom pathogen. While some strains cause disseminated fusariosis and blinding corneal infections in humans, others are responsible for devastating vascular wilt diseases in plants. To better understand the distinct adaptations of F. oxysporum to animal or plant hosts, we conducted a comparative phenotypic and genetic analysis of two strains: MRL8996 (isolated from a keratitis patient) and Fol4287 (isolated from a wilted tomato [Solanum lycopersicum]). In vivo infection of mouse corneas and tomato plants revealed that, while both strains cause symptoms in both hosts, MRL8996 caused more severe corneal ulceration and perforation in mice, whereas Fol4287 induced more pronounced wilting symptoms in tomato. In vitro assays using abiotic stress treatments revealed that the human pathogen MRL8996 was better adapted to elevated temperatures, whereas the plant pathogen Fol4287 was more tolerant of osmotic and cell wall stresses. Both strains displayed broad resistance to antifungal treatment, with MRL8996 exhibiting the paradoxical effect of increased tolerance to higher concentrations of the antifungal caspofungin. We identified a set of accessory chromosomes (ACs) and protein-encoding genes with distinct transposon profiles and functions, respectively, between MRL8996 and Fol4287. Interestingly, ACs from both genomes also encode proteins with shared functions, such as chromatin remodeling and post-translational protein modifications. Our phenotypic assays and comparative genomics analyses lay the foundation for future studies correlating genotype with phenotype and for developing targeted antifungals for agricultural and clinical uses.

Antifungal activity of bio-active cell-free culture extracts and volatile organic compounds (VOCs) synthesised by endophytic fungal isolates of Garden Nasturtium

Antimicrobial resistance in fungal pathogens (both human and plant) is increasing alarmingly, leading to massive economic crises. The existing anti-fungal agents are becoming ineffective, and the situation worsens on a logarithmic scale. Novel antifungals from unique natural sources are highly sought to cope sustainably with the situation. Metabolites from endophytic microbes are the best-fitted alternatives in this case. Endophytes are the untapped sources of 'plants' internal microbial population' and are promising sources of effective bio-therapeutic agents. Fungal endophytes were isolated from Tropaeolum majus and checked for antifungal activity against selected plant and human pathogens. Bioactive metabolites were identified through chromatographic techniques. The mode of action of those metabolites was evaluated through various spectroscopic techniques. The production of antifungal metabolite was optimized also. In particular VOCs (volatile organic compounds) of TML9 were tested in vitro for their anti-phytopathogenic activity. Ethyl acetate (EA) extract of cell-free culture components of Colletotrichum aenigma TML3 exhibited broad-spectrum antifungal activity against four species of Candida and the major constituents reported were 6-pentyl-2H-pyran-2-one, 2-Nonanone, 1 propanol 2-amino. The volatile metabolites, trans-ocimene, geraniol, and 4-terpinyl acetate, produced from Curvularia lunata TML9, inhibited the growth of some selected phyto pathogens. EA extract hampered the biofilm formation, minimised the haemolytic effect, and blocked the transformation of Candida albicans (MTCC 4748) from yeast to hyphal form with a Minimum Fungicidal Concentration (MFC) of 200-600 µg mL-1. Central carbohydrate metabolism, ergosterol synthesis, and membrane permeability were adversely affected and caused the lethal leakage of necessary macromolecules of C. albicans. Volatile metabolites inhibited the growth of phytopathogens i.e., Rhizoctonia solani, Alternaria alternata, Botrytis cinerea, Cercospora beticola, Penicillium digitatum, Aspergillus fumigatus, Ceratocystis ulmi, Pythium ultimum up to 89% with an IC50 value of 21.3-69.6 µL 50 mL-1 and caused leakage of soluble proteins and other intracellular molecules. Citrusy sweet odor volatiles of TML9 cultured in wheat-husk minimised the infections of Penicillium digitatum (green mold), in VOC-exposed sweet oranges (Citrus sinensis). Volatile and non-volatile antifungal metabolites of these two T. majus endophytes hold agricultural and pharmaceutical interests. Metabolites of TML3 have strong anti-Candida activity and require further assessment for therapeutic applications. Also, volatile metabolites of TML9 can be further studied as a source of antifungals. The present investigational outcomes bio-prospects the efficacy of fungal endophytes of Garden Nasturtium.

Salicylic acid-doped iron nano-biostimulants potentiate defense responses and suppress Fusarium wilt in watermelon

INTRODUCTION

Chemo- and bio-genic metallic nanoparticles (NPs), as a novel nano-enabled strategy, have demonstrated a great potential in crop health management.

OBJECTIVE

The current study aimed to explore the efficacy of advanced nanocomposites (NCs), integrating biogenic (bio) metallic NPs and plant immunity-regulating hormones, in crop disease control.

METHODS

Iron (Fe) NPs were biosynthesized using cell-free supernatant of a Fe-resistant strains, Bacillus marisflavi ZJ-4. Further, salicylic acid-coated bio-FeNPs (SI) NCs were prepared via co-precipitation method under alkaline conditions. Both bio-FeNPs and SINCs were characterized using basic analytical techniques, including Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction analysis, and scanning/transmission electron microscopy.

RESULTS

Bio-FeNPs and SINCs had variable shapes with average sizes of 72.35 nm and 65.87 nm, respectively. Under greenhouse conditions, bio-FeNPs and SINCs improved the agronomic traits of the watermelon plants, and SINCs outperformed bio-FeNPs, providing the maximum growth promotion of 32.5%. Soil-drenching with bio-FeNPs and SINCs suppressed Fusarium oxysporum f. sp. niveum-caused Fusarium wilt in watermelon, and SINCs provided better protection than bio-FeNPs, through inhibiting the fungal invasive growth within host plants. SINCs improved the antioxidative capacity and primed a systemic acquired resistance (SAR) response via activating the salicylic acid signaling pathway genes. These findings indicate that SINCs can reduce the severity of Fusarium wilt in watermelon by modulating antioxidative capacity and potentiating SAR to restrict in planta fungal invasive growth.

CONCLUSION

This study provides new insights into the potential of bio-FeNPs and SINCs as biostimulants and bioprotectants for growth promotion and Fusarium wilt suppression, ensuring sustainable watermelon production.

Pathogenicity, Host Resistance, and Genetic Diversity of Fusarium Species under Controlled Conditions from Soybean in Canada

Fusarium spp. are commonly associated with the root rot complex of soybean (Glycine max). Previous surveys identified six common Fusarium species from Manitoba, including F. oxysporum, F. redolens, F. graminearum, F. solani, F. avenaceum, and F. acuminatum. This study aimed to determine their pathogenicity, assess host resistance, and evaluate the genetic diversity of Fusarium spp. isolated from Canada. The pathogenicity of these species was tested on two soybean cultivars, 'Akras' (moderately resistant) and 'B150Y1' (susceptible), under greenhouse conditions. The aggressiveness of the fungal isolates varied, with root rot severities ranging from 1.5 to 3.3 on a 0-4 scale. Subsequently, the six species were used to screen a panel of 20 Canadian soybean cultivars for resistance in a greenhouse. Cluster and principal component analyses were conducted based on the same traits used in the pathogenicity study. Two cultivars, 'P15T46R2' and 'B150Y1', were consistently found to be tolerant to F. oxysporum, F. redolens, F. graminearum, and F. solani. To investigate the incidence and prevalence of Fusarium spp. in Canada, fungi were isolated from 106 soybean fields surveyed across Manitoba, Saskatchewan, Ontario, and Quebec. Eighty-three Fusarium isolates were evaluated based on morphology and with multiple PCR primers, and phylogenetic analyses indicated their diversity across the major soybean production regions of Canada. Overall, this study contributes valuable insights into host resistance and the pathogenicity and genetic diversity of Fusarium spp. in Canadian soybean fields.

The Ser/Thr protein kinase FonKin4-poly(ADP-ribose) polymerase FonPARP1 phosphorylation cascade is required for the pathogenicity of watermelon fusarium wilt fungus Fusarium oxysporum f. sp. niveum

Poly(ADP-ribosyl)ation (PARylation), catalyzed by poly(ADP-ribose) polymerases (PARPs) and hydrolyzed by poly(ADP-ribose) glycohydrolase (PARG), is a kind of post-translational protein modification that is involved in various cellular processes in fungi, plants, and mammals. However, the function of PARPs in plant pathogenic fungi remains unknown. The present study investigated the roles and mechanisms of FonPARP1 in watermelon Fusarium wilt fungus Fusarium oxysporum f. sp. niveum (Fon). Fon has a single PARP FonPARP1 and one PARG FonPARG1. FonPARP1 is an active PARP and contributes to Fon pathogenicity through regulating its invasive growth within watermelon plants, while FonPARG1 is not required for Fon pathogenicity. A serine/threonine protein kinase, FonKin4, was identified as a FonPARP1-interacting partner by LC-MS/MS. FonKin4 is required for vegetative growth, conidiation, macroconidia morphology, abiotic stress response and pathogenicity of Fon. The S_TKc domain is sufficient for both enzyme activity and pathogenicity function of FonKin4 in Fon. FonKin4 phosphorylates FonPARP1 in vitro to enhance its poly(ADP-ribose) polymerase activity; however, FonPARP1 does not PARylate FonKin4. These results establish the FonKin4-FonPARP1 phosphorylation cascade that positively contributes to Fon pathogenicity. The present study highlights the importance of PARP-catalyzed protein PARylation in regulating the pathogenicity of Fon and other plant pathogenic fungi.

Nanowarriors from Mentha: Unleashing Nature's Antimicrobial Arsenal with Cerium Oxide Nanoparticles

Medicinal plant-based cerium oxide nanoparticles (CeO2NPs) possessed excellent antimicrobial properties against multiple strains of Gram-positive and Gram-negative bacteria. The CeO2NPs are popular because their electropositive charged surface causes oxidation of plasma membrane and facilitates the penetration of CeO2NPs inside the pathogen body. In the present research work, CeO2NPs stabilized with Mentha leaf extract; as a result, nanoparticles surface-bonded with various functional groups of phytochemicals which enhanced the therapeutic potential of CeO2NPs. The inhibition percentage of CeO2NPs was evaluated against eight pathogenic Gram-positive bacteria Staphylococcus aureus and Streptococcus epidermidis; Gram-negative bacteria Escherichia coli, Stenotrophomonas maltophilia, Comamonas sp., Halobacterium sp., and Klebsiella pneumoniae; and plant bacteria Xanthomonas sp. The antifungal properties of CeO2NPs were evaluated against three pathogenic fungal species Bipolaris sorokiniana, Aspergillus flavus, and Fusarium oxysporum via the streak plate method. The antimicrobial inhibitory activity of CeO2NPs was good to excellent. The current research work clearly shows that three different medicinal plants Mentha royleana, Mentha longifolia, and Mentha arvensis based CeO2NPs, variation in nanoparticle sizes, and surface-to-volume ratio of green CeO2NPs are three factors responsible to generate and provoke antimicrobial activities of CeO2NPs against human pathogenic bacteria and plant infecting fungi. The results show that CeO2NPs possessed good antimicrobial properties and are effective to use for pharmaceutical applications and as a food preservative because of low toxicity, organic coating, and acceptable antimicrobial properties. This study showed a rapid and well-organized method to prepare stable phytochemical-coated CeO2NPs with three different plants M. royleana, M. longifolia, and M. arvensis with remarkable antibacterial and antifungal characteristics.

Molecular characterization of Indian races of Fusarium oxysporum f. sp. lentis (Fol) based on secreted in Xylem (SIX) effector genes and development of a SIX11 gene-based molecular marker for specific detection of Fol

Fusarium wilt of lentil caused by Fusarium oxysporum f. sp. lentis (Fol) is a destructive pathogen limiting lentil production in India. In the present study, Secreted in Xylem (SIX) effectors genes were explored in Indian races of Fol and also a diagnostic tool for reliable detection of the disease was developed. Four SIX effectors genes, SIX11, SIX13, SIX6 and SIX2 were identified in 12 isolates of Fol belonging to seven races. SIX11 was present in all the races while SIX 13 was absent in race 6 and SIX6 was present only in race 4. The phylogenetic analysis revealed the conserved nature of the SIX genes within the forma specialis and showed sequence homology with F. oxysporum f. sp. pisi. The presence of three effectors, SIX11, SIX13 and SIX6 in race 4 correlates with high disease incidence in lentil germplasms. The in-silico characterization revealed the presence of signal peptide and localization of the effectors. Further SIX11 effector gene present in all the isolates was used to develop Fol-specific molecular marker for accurate detection. The marker developed could differentiate F. oxysporum f. sp. lycopersici, F. solani, F. oxysporum, Rhizoctonia solani and Sclerotium rolfsii and had a detection limit of 0.01ng μL- 1. The effector-based marker detection helps in the unambiguous detection of the pathogen under field conditions.

Characterization of the High-Quality Genome Sequence and Virulence Factors of Fusarium oxysporum f. sp. vasinfectum Race 7

Fusarium oxysporum f. sp. vasinfectum (Fov) is a common soilborne fungal pathogen that causes Fusarium wilt (FW) disease in cotton. Although considerable progress has been made in cotton disease-resistance breeding against FW in China, and the R gene conferring resistance to Fov race 7 (FOV) in Upland cotton (Gossypium hirsutum) has been identified, knowledge regarding the evolution of fungal pathogenicity and virulence factors in Fov remains limited. In this study, we present a reference-scale genome assembly and annotation for FOV7, created through the integration of single-molecule real-time sequencing (PacBio) and high-throughput chromosome conformation capture (Hi-C) techniques. Comparative genomics analysis revealed the presence of six supernumerary scaffolds specific to FOV7. The genes or sequences within this region can potentially serve as reliable diagnostic markers for distinguishing Fov race 7. Furthermore, we conducted an analysis of the xylem sap proteome of FOV7-infected cotton plants, leading to the identification of 19 proteins that are secreted in xylem (FovSIX). Through a pathogenicity test involving knockout mutants, we demonstrated that FovSIX16 is crucial for the full virulence of FOV7. Overall, this study sheds light on the underlying mechanisms of Fov's pathogenicity and provides valuable insights into potential management strategies for controlling FW.

Facilitating Effects of Reductive Soil Disinfestation on Soil Health and Physiological Properties of Panax ginseng

Chemical soil fumigation (CSF) and reductive soil disinfestation (RSD) have been proven to be effective agricultural strategies to improve soil quality, restructure microbial communities, and promote plant growth in soil degradation remediation. However, it is still unclear how RSD and CSF ensure soil and plant health by altering fungal communities. Field experiments were conducted to investigate the effects of CSF with chloropicrin, and RSD with animal feces on soil properties, fungal communities and functional composition, and plant physiological characteristics were evaluated. Results showed that RSD and CSF treatment improved soil properties, restructured fungal community composition and structure, enhanced fungal interactions and functions, and facilitated plant growth. There was a significant increase in OM, AN, and AP contents in the soil with both CSF and RSD treatments compared to CK. Meanwhile, compared with CK and CSF, RSD treatment significantly increased biocontrol Chaetomium relative abundance while reducing pathogenic Neonectria relative abundance, indicating that RSD has strong inhibition potential. Furthermore, the microbial network of RSD treatment was more complex and interconnected, and the functions of plant pathogens, and animal pathogen were decreased. Importantly, RSD treatment significantly increased plant SOD, CAT, POD activity, SP, Ca, Zn content, and decreased MDA, ABA, Mg, K, and Fe content. In summary, RSD treatment is more effective than CSF treatment, by stimulating the proliferation of probiotic communities to further enhance soil health and plant disease resistance.

Complete genome sequence of a novel dsRNA virus from the phytopathogenic fungus Fusarium oxysporum

Fusarium oxysporum is a widespread plant pathogen that causes fusarium wilt and fusarium root rot in many economically significant crops. Here, a novel dsRNA virus tentatively named "Fusarium oxysporum virus 1" (FoV1) was identified in F. oxysporum strain 3S-18. The genome of FoV1 is 2,944 nucleotides (nt) in length and contains two non-overlapping open reading frames (ORF1 and 2). The larger of these, ORF2, encodes an RNA-dependent RNA polymerase (RdRp) of 590 amino acids with a molecular mass of 67.52 kDa. ORF1 encodes a putative nucleocapsid protein consisting of 134 amino acids with a molecular mass of 34.25 kDa. The RdRp domain of FoV1 shares 60.00% to 84.24% sequence identity with non-segmented dsRNA viruses. Phylogenetic analysis further suggested that FoV1 is a new member of the proposed genus "Unirnavirus" accommodating unclassified monopartite dsRNA viruses.

Histopathology and quantification of green fluorescent protein-tagged Fusarium oxysporum f. sp. luffae isolate in resistant and susceptible Luffa germplasm

Fusarium oxysporum f. sp. luffae (Folu) is a severe plant pathogen that causes vascular wilt and root rot in Luffa plants worldwide. A green fluorescent protein (GFP)-tagged isolate of Folu (Fomh16-GFP) was utilized to investigate the infection progress and colonization of Fomh16-GFP in resistant (LA140) and susceptible (LA100) Luffa genotypes. Seven days post-inoculation (dpi), it was observed that Fomh16-GFP had successfully invaded and colonized the vascular bundle of all LA100 parts, including the roots, hypocotyl, and stem. Pathogen colonization continued to increase over time, leading to the complete wilting of plants by 14-17 dpi. In LA140, the Fomh16-GFP isolate colonized the roots and hypocotyl vascular system at 7 dpi. Nevertheless, this colonization was restricted in the hypocotyl and decreased significantly, and no fungal growth was detected in the vascular system at 21 dpi. Thus, the resistant genotype might trigger a robust defense mechanism. In addition, while the pathogen was present in LA140, the inoculated plants did not exhibit any symptoms until 28 dpi. Quantitative PCR was utilized to measure the Fomh16-GFP biomass in various parts of LA100 and LA140 at different time points. The findings indicated a positive correlation between the quantity of Fomh16-GFP DNA and disease development in LA100. Alternatively, a high amount of Fomh16-GFP DNA was identified in the roots of LA140. Nonetheless, no significant correlations were found between DNA amount and disease progression in LA140. Aqueous extracts from LA140 significantly reduced Fomh16-GFP spore germination, while no significant reduction was detected using LA100 extracts.IMPORTANCEFusarium wilt of Luffa, caused by Fusarium oxysporum f. sp. luffae (Folu), causes great losses in Luffa plants worldwide. This study used a green fluorescent protein (GFP)-tagged isolate of Folu (Fomh16-GFP) to investigate the infection progress and colonization dynamics of Fomh16-GFP in the resistant and susceptible Luffa genotypes, which could be important in understanding the resistance mechanism of Folu in Luffa plants. In addition, our work highlights the correlations between DNA amount and disease progression in resistant plants using real-time PCR. We observed a positive correlation between the quantity of Fomh16-GFP DNA and disease progression in LA100, while no significant correlation was found in LA140. These results could be valuable to further investigate the resistance mechanism of Luffa genotypes against Folu. Gaining a better understanding of the interaction between Folu and Luffa plants is crucial for effectively managing Fusarium wilt and enhancing resistance in Luffa rootstock and its varieties.

Pathogenicity chromosome of Fusarium oxysporum f. sp. cepae

Fusarium oxysporum f. sp. cepae (Foc) is the causative agent of Fusarium basal rot disease in onions, which leads to catastrophic global crop production losses. Therefore, the interaction of Foc with its host has been actively investigated, and the pathogen-specific (PS) regions of the British strain Foc_FUS2 have been identified. However, it has not been experimentally determined whether the identified PS region plays a role in pathogenicity. To identify the pathogenicity chromosome in the Japanese strain Foc_TA, we initially screened effector candidates, defined as small proteins with a signal peptide that contain two or more cysteines, from genome sequence data. Twenty-one candidate effectors were identified, five of which were expressed during infection. Of the expressed effector candidates, four were located on the 4-Mb-sized chromosome in Foc_TA. To clarify the relationship between pathogenicity and the 4-Mb-sized chromosome in Foc_TA, nine putative 4-Mb-sized chromosome loss strains were generated by treatment with benomyl (a mitotic inhibitor drug). A pathogenicity test with putative 4-Mb-sized chromosome loss strains showed that these strains were impaired in their pathogenicity toward onions. Genome analysis of three putative 4-Mb-sized chromosome loss strains revealed that two strains lost a 4-Mb-sized chromosome in common, and another strain maintained a 0.9-Mb region of the 4-Mb-sized chromosome. Our findings show that the 4-Mb-sized chromosome is the pathogenicity chromosome in Foc_TA, and the 3.1-Mb region within the 4-Mb-sized chromosome is required for full pathogenicity toward onion.

Fine-mapping of a major locus for Fusarium wilt resistance in flax (Linum usitatissimum L.)

KEY MESSAGE

Fine-mapping of a locus on chromosome 1 of flax identified an S-lectin receptor-like kinase (SRLK) as the most likely candidate for a major Fusarium wilt resistance gene. Fusarium wilt, caused by the soil-borne fungal pathogen Fusarium oxysporum f. sp. lini, is a devastating disease in flax. Genetic resistance can counteract this disease and limit its spread. To map major genes for Fusarium wilt resistance, a recombinant inbred line population of more than 700 individuals derived from a cross between resistant cultivar 'Bison' and susceptible cultivar 'Novelty' was phenotyped in Fusarium wilt nurseries at two sites for two and three years, respectively. The population was genotyped with 4487 single nucleotide polymorphism (SNP) markers. Twenty-four QTLs were identified with IciMapping, 18 quantitative trait nucleotides with 3VmrMLM and 108 linkage disequilibrium blocks with RTM-GWAS. All models identified a major QTL on chromosome 1 that explained 20-48% of the genetic variance for Fusarium wilt resistance. The locus was estimated to span ~ 867 Kb but included a ~ 400 Kb unresolved region. Whole-genome sequencing of 'CDC Bethune', 'Bison' and 'Novelty' produced ~ 450 Kb continuous sequences of the locus. Annotation revealed 110 genes, of which six were considered candidate genes. Fine-mapping with 12 SNPs and 15 Kompetitive allele-specific PCR (KASP) markers narrowed down the interval to ~ 69 Kb, which comprised the candidate genes Lus10025882 and Lus10025891. The latter, a G-type S-lectin receptor-like kinase (SRLK) is the most likely resistance gene because it is the only polymorphic one. In addition, Fusarium wilt resistance genes previously isolated in tomato and Arabidopsis belonged to the SRLK class. The robust KASP markers can be used in marker-assisted breeding to select for this major Fusarium wilt resistance locus.

Transcriptome Analysis and Reactive Oxygen Species Detection Suggest Contrasting Molecular Mechanisms in Populus canadensis' Response to Different Formae Speciales of Marssonina brunnea

Revealing plant-pathogen interactions is important for resistance breeding, but it remains a complex process that presents many challenges. Marssonina leaf spot of poplars (MLSP) is the main disease in poplars; in China, its pathogens consist of two formae speciales, namely, Marssonina brunnea f. sp. Monogermtubi (MO) and M. brunnea f. sp. Multigermtubi (MU). However, the mechanism of the molecular interaction between poplars and the two formae speciales, especially for an incompatible system, remains unclear. In this study, we conducted transcriptome sequencing and reactive oxygen species (ROS) staining based on the interactions between Populus canadensis and the two formae speciales. The results show that the gene expression patterns of P. canadensis induced by MO and MU were significantly different, especially for the genes associated with biotic stress. Furthermore, MO and MU also triggered distinct ROS reactions of P. canadensis, and ROS (mainly H2O2) burst was only observed around the cells penetrated by MU. In conclusion, this study suggested that P. canadensis experienced different resistance reactions in response to the two formae speciales of M. brunnea, providing valuable insights for further understanding the host-pathogen interactions of MLSP.

Transcriptomic-Proteomic Analysis Revealed the Regulatory Mechanism of Peanut in Response to Fusarium oxysporum

Peanut Fusarium rot, which is widely observed in the main peanut-producing areas in China, has become a significant factor that has limited the yield and quality in recent years. It is highly urgent and significant to clarify the regulatory mechanism of peanuts in response to Fusarium oxysporum. In this study, transcriptome and proteome profiling were combined to provide new insights into the molecular mechanisms of peanut stems after F. oxysporums infection. A total of 3746 differentially expressed genes (DEGs) and 305 differentially expressed proteins (DEPs) were screened. The upregulated DEGs and DEPs were primarily enriched in flavonoid biosynthesis, circadian rhythm-plant, and plant-pathogen interaction pathways. Then, qRT-PCR analysis revealed that the expression levels of phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), and cinnamic acid-4-hydroxylase (C4H) genes increased after F. oxysporums infection. Moreover, the expressions of these genes varied in different peanut tissues. All the results revealed that many metabolic pathways in peanut were activated by improving key gene expressions and the contents of key enzymes, which play critical roles in preventing fungi infection. Importantly, this research provides the foundation of biological and chemical analysis for peanut disease resistance mechanisms.

Controlling Tomato Fusarium Wilt Disease through Bacillus thuringiensis-Mediated Defense Primining

Background

Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. lycopersici (Fol) (Sacc.) W.C. Snyder and H.N. Hans is one of the most prevalent and devastating diseases of tomato plants (Solanum lycoprsicum L.) that leads to a severe reduction in crop yield almost worldwide.

Objective

Evaluation of biocontrol potential of Bacillus thuringiensis (Bt) isolate IBRC-M11096, against Fol in tomato through primin.

Materials and Methods

qRT-PCR technique was applied to analyze the effect of the strain on the hormonal defensive pathways; transcriptional responses of jasmonic acid (COI1, Pin2) and salicylic acid (NRP1 and PR1) pathway genes in Bt-treated plants following inoculation of Fol as compared to the plants only challenged with Fol. Also, the potential of the bacterial strain as a biocontrol agent was studied by evaluating growth indices and area under disease progress curve (AUDPC).

Results

The transcription of both defensive hormonal pathway genes (COI1, Pin2, NPR1, PR1) increased due to bacterial priming. The bacterial priming reduced the AUDPC compared to the inoculation with only Fol. The strain reduced the disease symptoms, and compared to the plants only challenged with the fungus, the bacterial strain significantly raised shoot dry and fresh weights and root dry weight.

Conclusion

Priming with the Bt strain led to improved shoot and root growth indices, reduced AUDPC, and fortified responses of both JA and SA hormonal pathways. However, further full-span studies are required to judge the efficacy of the bacterial strain in the biological control of tomato fusarium wilt under field conditions.

Exploring the infiltrative and degradative ability of Fusarium oxysporum on polyethylene terephthalate (PET) using correlative microscopy and deep learning

Managing the worldwide steady increase in the production of plastic while mitigating the Earth's global pollution is one of the greatest challenges nowadays. Fungi are often involved in biodegradation processes thanks to their ability to penetrate into substrates and release powerful catabolic exoenzymes. However, studying the interaction between fungi and plastic substrates is challenging due to the deep hyphal penetration, which hinders visualisation and evaluation of fungal activity. In this study, a multiscale and multimodal correlative microscopy workflow was employed to investigate the infiltrative and degradative ability of Fusarium oxysporum fungal strain on polyethylene terephthalate (PET) fragments. The use of non-destructive high-resolution 3D X-ray microscopy (XRM) coupled with a state-of-art Deep Learning (DL) reconstruction algorithm allowed optimal visualisation of the distribution of the fungus on the PET fragment. The fungus preferentially developed on the edges and corners of the fragment, where it was able to penetrate into the material through fractures. Additional analyses with scanning electron microscopy (SEM), Raman and energy dispersive X-ray spectroscopy (EDX) allowed the identification of the different phases detected by XRM. The correlative microscopy approach unlocked a more comprehensive understanding of the fungus-plastic interaction, including elemental information and polymeric composition.

Isolation and Identification of Bacillus subtilis LY-1 and Its Antifungal and Growth-Promoting Effects

Peanut root rot, caused by Fusarium spp., is a devastating fungal disease. As part of a program to obtain a biocontrol agent to control peanut root rot in the field, a bacterial strain LY-1 capable of inhibiting the growth of the fungus in vitro was isolated from rhizosphere soil samples collected from wild mint by agar disk dilution and dual-culture assay. Strain LY-1 was identified as Bacillus subtilis based on morphological characteristics, 16S rDNA, and gyrA sequence analyses. The bacterial suspension and cell-free culture filtrate of LY-1 could significantly inhibit the growth of Fusarium oxysporum, Fusarium proliferatum and Fusarium solani, but volatile organic compounds from the cultures had only a weak effect on mycelial growth. The percentage inhibition of 20% concentration of the cell-free culture filtrate of LY-1 on conidium production of each of the three Fusarium species was greater than 72.38%, and the percentage inhibition by the culture filtration on the germination of conidia of the three species was at least 62.37%. The production of extracellular enzyme activity by LY-1 was studied in functional assays, showing protease, cellulase, amylase, chitinase, and β-1,3-glucanase activity, while LY-1 contained a gene encoding iturin, an antifungal lipopeptide. In addition, under pot culture in a greenhouse, culture filtrate of LY-1 significantly promoted the growth of peanut, increasing the fresh and dry mass of the plant by 30.77% and 27.27%, respectively, in comparison with the no-filtrate control. The culture filtrate of LY-1 increased the resistance of peanut plants to F. oxysporum, with the biocontrol efficiency reaching 44.71%. In conclusion, B. subtilis LY-1, a plant-growth-promoting rhizobacterium, was able to protect peanuts from Fusarium spp. infection.

Isolation and evaluation of Qatari soil rhizobacteria for antagonistic potential against phytopathogens and growth promotion in tomato plants

Plant growth promoting rhizobacteria are a diverse group of microorganisms that enhance the growth of plants under various conditions. In this study, 55 isolates of endogenous rhizobacteria were collected from the rhizosphere of Avicennia marina, Suaeda vermiculata, Salsola soda, Anabasis setifera, Salicornia europaea, Arthrocnemum macrostachyum, Limonium axillare, Tetraena qatarensis, Aeluropus lagopoides, and Prosopis juliflora. The isolates were evaluated in-vitro for their antagonist potential against Fusarium oxysporum and Botrytis cinerea using the dual culture technique, where the maximum growth inhibition reached 49% and 57%, respectively. In-vivo evaluation was accomplished to determine the growth-promoting potential of the rhizobacteria under greenhouse conditions where the strain ANABR3 (Bacillus subtilis) showed the strongest growth-promoting effects. Further in-vivo testing regarding the effectiveness of rhizobacteria in the presence of the phytopathogen was also completed using the Hoagland medium. LEMR3 and SALIR5 (both identified as two strains of B. subtilis) supported the tomato seedlings to overcome the disease and significantly (p ≤ 0.05) increased above and belowground biomass compared to the control. Additionally, several characterizing tests were carried out on the selected strains, these strains were found to possess numerous features that promote plant growth directly and indirectly such as the production of IAA, HCN, hydrolytic enzymes, ACC deaminase, NH3, and some rhizobacteria were capable of phosphate solubilization. In conclusion, this study showed that local rhizobacterial isolates collected from arid lands possess valuable traits, making them promising bio-control agents and bio-fertilizers for agricultural purposes.

Microbial diversity in soils suppressive to Fusarium diseases

Fusarium species are cosmopolitan soil phytopathogens from the division Ascomycota, which produce mycotoxins and cause significant economic losses of crop plants. However, soils suppressive to Fusarium diseases are known to occur, and recent knowledge on microbial diversity in these soils has shed new lights on phytoprotection effects. In this review, we synthesize current knowledge on soils suppressive to Fusarium diseases and the role of their rhizosphere microbiota in phytoprotection. This is an important issue, as disease does not develop significantly in suppressive soils even though pathogenic Fusarium and susceptible host plant are present, and weather conditions are suitable for disease. Soils suppressive to Fusarium diseases are documented in different regions of the world. They contain biocontrol microorganisms, which act by inducing plants' resistance to the pathogen, competing with or inhibiting the pathogen, or parasitizing the pathogen. In particular, some of the Bacillus, Pseudomonas, Paenibacillus and Streptomyces species are involved in plant protection from Fusarium diseases. Besides specific bacterial populations involved in disease suppression, next-generation sequencing and ecological networks have largely contributed to the understanding of microbial communities in soils suppressive or not to Fusarium diseases, revealing different microbial community patterns and differences for a notable number of taxa, according to the Fusarium pathosystem, the host plant and the origin of the soil. Agricultural practices can significantly influence soil suppressiveness to Fusarium diseases by influencing soil microbiota ecology. Research on microbial modes of action and diversity in suppressive soils should help guide the development of effective farming practices for Fusarium disease management in sustainable agriculture.

Virulence factors of the genus Fusarium with targets in plants

Fusarium spp. comprise various species of filamentous fungi that cause severe diseases in plant crops of both agricultural and forestry interest. These plant pathogens produce a wide range of molecules with diverse chemical structures and biological activities. Genetic functional analyses of some of these compounds have shown their role as virulence factors (VF). However, their mode of action and contributions to the infection process for many of these molecules are still unknown. This review aims to analyze the state of the art in Fusarium VF, emphasizing their biological targets on the plant hosts. It also addresses the current experimental approaches to improve our understanding of their role in virulence and suggests relevant research questions that remain to be answered with a greater focus on species of agroeconomic importance. In this review, a total of 37 confirmed VF are described, including 22 proteinaceous and 15 non-proteinaceous molecules, mainly from Fusarium oxysporum and Fusarium graminearum and, to a lesser extent, in Fusarium verticillioides and Fusarium solani.

Evaluation of Hydrangea Cultivars for Tolerance Against Root Rot Caused by Fusarium oxysporum

Root rot caused by Fusarium oxysporum Schltdl. is a newly identified disease in oakleaf hydrangea. Some cultivars such as Pee Wee and Queen of Hearts grown in pot-in-pot container systems showed root rot symptoms after late spring frost in May 2018 with 40 and 60% incidence in the infected nursery, respectively. This experiment was carried out to evaluate the tolerance among different hydrangea cultivars against root rot caused by F. oxysporum. Fifteen hydrangea cultivars from four different species were selected, and rooted cuttings were prepared from new spring flushes. Twelve plants from each cultivar were transplanted in a 1-gallon pot. Half of transplanted plants (six single plants) were inoculated by drenching 150 ml of F. oxysporum conidial suspension to maintain the concentration of 1 × 106 conidia/ml. Half of the plants remain noninoculated (control) and were drenched with sterile water. After 4 months, root rot was assessed using a scale of 0 to 100% root area affected, and recovery of F. oxysporum was recorded by plating 1-cm root sections in Fusarium selective medium. Fusaric acid (FA) and mannitol were extracted from the roots of inoculated and noninoculated plants to see the effect and role on pathogenesis. Further, mannitol concentration was analyzed using absorption wavelength in a spectrophotometer, and FA was analyzed using high-performance liquid chromatography (HPLC). Results indicated that no cultivars were resistant to F. oxysporum. Cultivars from Hydrangea arborescens, H. macrophylla, and H. paniculata were more tolerant to F. oxysporum compared to cultivars from H. quercifolia. Among H. quercifolia, cultivars Snowflake, John Wayne, and Alice were more tolerant to F. oxysporum.

The SIX5 Protein in Fusarium oxysporum f. sp. cepae Acts as an Avirulence Effector toward Shallot (Allium cepa L. Aggregatum Group)

Fusarium oxysporum f. sp. cepae (Foc) causes basal rot disease in Allium species, including onions (Allium cepa L.) and shallots (A. cepa L. Aggregatum group). Among Allium species, shallots can be crossbred with onions and are relatively more resistant to Foc than onions. Thus, shallots are considered a potential disease-resistant resource for onions. However, the mechanisms underlying the molecular interactions between shallots and Foc remain unclear. This study demonstrated that SIX5, an effector derived from Foc (FocSIX5), acts as an avirulence effector in shallots. We achieved this by generating a FocSIX5 gene knockout mutant in Foc, for which experiments which revealed that it caused more severe wilt symptoms in Foc-resistant shallots than the wild-type Foc and FocSIX5 gene complementation mutants. Moreover, we demonstrated that a single amino acid substitution (R67K) in FocSIX5 was insufficient to overcome shallot resistance to Foc.

Identification and screening of fungicides against Piper nigrum basal Fusarium wilt disease in Hainan, China

Fusarium wilt has occurred in the main Piper nigrum cultivation regions, which seriously affects the yield and quality of P. nigrum. To identify the pathogen of this disease, the diseased roots were collected from a demonstration base in Hainan Province. The pathogen was obtained by tissue isolation method and confirmed by pathogenicity test. Based on the morphological observation, sequence analyses of TEF1-α nuclear gene, Fusarium solani was identified as the pathogen causing P. nigrum Fusarium wilt and induced symptoms on inoculated plants, including chlorosis, necrotic spots, wilt, drying, and root rot. The experiments for the antifungal activity showed that all the 11 fungicides selected in this study showed certain inhibitory effects on the colony growth of F. solani, where 2% kasugamycin AS, 45% prochloraz EW, 25 g·L-1 fludioxonil SC and 430 g·L-1 tebuconazole SC exhibited relative higher inhibitory effects with EC50 as 0.065, 0.205, 0.395, and 0.483 mg·L-1 , respectively, and were selected to perform SEM analysis and test in seeds in vitro. The SEM analysis showed that kasugamycin, prochloraz, fludioxonil, and tebuconazole might have exerted their antifungal effect by damaging F. solani mycelia or microconidia. These preparations were applied as a seed coating of P. nigrum Reyin-1. The kasugamycin treatment was most effective in reducing the harmful impact of F. solani on the seed germination. These results presented herein provide useful guidance for the effective control of P. nigrum Fusarium wilt.

The determination of the biological function of bacterial pink pigment and Fusarium chlamydosporum on alfalfa (Medicago sativa L.)

Bacterial pigment is one of the secondary metabolites produced by bacteria and has functions that are yet to be understood in relation to soil-borne pathogenic fungi and plants in mutualistic processes. The study evaluates the growth, photosynthetic, and physiological characteristics of alfalfa after interacting with different concentrations of Cp2 pink pigment and Fusarium chlamydosporum. The findings showed that Cp2 pink pigment has the ability to inhibit the growth of alfalfa, with the inhibition ratio gradually increasing with rising concentration. F. chlamydosporum inhibited the growth of alfalfa, which reduced the photosynthetic physiological response and elevated antioxidant enzymes, which are typically manifested by yellowing leaves and shortened roots. Under the combined effect of Cp2 pink pigment and F. chlamydosporum, increasing concentrations of Cp2 pink pigment intensified the symptoms in alfalfa and led to more pronounced growth and physiological response. This indicates that the Cp2 pink pigment is one of the potential virulence factors secreted by the Erwinia persicina strain Cp2, which plays an inhibitory role in the interactions between F. chlamydosporum and alfalfa, and also has the potential to be developed into a plant immunomodulator agent.

The Green Synthesis of Silver Nanoparticles from Avena fatua Extract: Antifungal Activity against Fusarium oxysporum f.sp. lycopersici

Using plant extracts as eco-friendly reducing and stabilizing agents for the synthesis of nanoparticles has gained significant attention in recent years. The current study explores the green synthesis of silver nanoparticles (AgNPs) using the Avena fatua extract and evaluates their antifungal activity against Fusarium oxysporum f.sp. lycopersici (Fol), a fungal plant pathogen. A green and sustainable approach was adopted to synthesize silver nanoparticles before these nanoparticles were employed for anti-fungal activity. The primary indication that AgNPs had formed was performed using UV-vis spectroscopy, where a strong peak at 425 nm indicated the effective formation of these nanoparticles. The indication of important functional groups acting as reducing and stabilizing agents was conducted using the FTIR study. Additionally, morphological studies were executed via SEM and AFM, which assisted with more effectively analyzing AgNPs. Crystalline behavior and size were estimated using powder XRD, and it was found that AgNPs were highly crystalline, and their size ranged from 5 to 25 nm. Synthesized AgNPs exhibited significant antifungal activity against Fol at a concentration of 40 ppm. Furthermore, the inhibitory index confirmed a positive correlation between increasing AgNPs concentration and exposure duration. This study suggests that the combined phytochemical mycotoxic effect of the plant extract and the smaller size of synthesized AgNPs were responsible for the highest penetrating power to inhibit Fol growth. Moreover, this study highlights the potential of using plant extracts as reducing and capping agents for the green synthesis of AgNPs with antifungal properties. The study concludes that A. fatua extract can synthesize antifungal AgNPs as a sustainable approach with robust antifungal efficacy against Fol, underscoring their promising potential for integration into plant protection strategies.

Identification and Chemical and Biological Management of Fusarium Root and Crown Rot Disease of Oakleaf Hydrangea

Oakleaf hydrangea (Hydrangea quercifolia) is an important ornamental plant grown in Tennessee. In May 2018, after late spring frost, cultivars Pee Wee and Queen of Hearts showed root and crown rot symptoms and identification and management of the disease was a major concern. The objective of this research was to identify the causal organism of this disease and develop management recommendations for nursery growers. Isolates from the infected root and crown parts were subjected to microscopy, and the morphology of fungi resembled Fusarium. Molecular analysis was conducted by amplifying the internal transcribed spacer of ribosomal DNA, β-tubulin, and translation elongation factor 1-α regions. Fusarium oxysporum was identified as a causal organism based on molecular analysis. A pathogenicity test was done to complete the Koch's postulates by drenching containerized oakleaf hydrangea with a conidial suspension. Experiments were conducted to evaluate different chemical fungicides and biological products with different rates for Fusarium root and crown rot management in container-grown Queen of Hearts. Plants were inoculated by drenching containerized oakleaf hydrangea with 150-ml conidial suspensions of F. oxysporum, maintaining the concentration of 1 × 106 conidia/ml. Root and crown rot were assessed using a scale of 0 to 100%. Recovery of F. oxysporum was recorded by plating root and crown sections. Chemical fungicides such as mefentrifluconazole (BAS75002F), the low rate (1.09 ml/liter) of difenoconazole + pydiflumetofen (Postiva), and the high rate (1.32 ml/liter) of isofetamid (Astun) and biopesticide were applied; the high rate (1.64 g/liter) of ningnanmycin (SP2700 WP) effectively reduced Fusarium root rot severity and pyraclostrobin effectively reduced Fusarium crown rot severity in both trials.

Identification and Characterization of Neocosmospora silvicola Causing Canker Disease on Pinus armandii in China

Chinese white pine, Pinus armandii, is a source of high-quality timber and an afforestation tree in China, which plays an important ecological and social role in water and soil conservation. Recently, a new canker disease has been reported in Longnan City, Gansu Province, where P. armandii is mainly distributed. In this study, the causal agent was isolated from diseased samples and identified as a fungal pathogen, Neocosmospora silvicola, based on morphological characteristics and molecular analyses (internal transcribed spacer, large subunit, RNA polymerase II, and translation elongation factor-1α). Pathogenicity tests on P. armandii revealed that N. silvicola isolates caused a 60% average mortality rate in artificially inoculated 2-year-old seedlings. The pathogenicity of these isolates was also observed on the branches of 10-year-old P. armandii trees with a 100% mortality rate. These results agree with the isolation of N. silvicola from diseased plants, suggesting the possible role of this fungus in the decline of P. armandii plants. Mycelial growth of N. silvicola was fastest on potato dextrose agar medium, and growth occurred at pH values ranging from 4.0 to 11.0 with temperatures between 5 and 40°C. The fungus also grew rapidly in complete darkness compared with other light conditions. Of the eight carbon and seven nitrogen sources tested, starch and sodium nitrate, respectively, were highly efficient in supporting the mycelial growth of N. silvicola. The ability of N. silvicola to grow at low temperatures (5°C) may explain its occurrence in the Longnan area of Gansu Province. This article is the first report of N. silvicola as an important fungal pathogen causing branch and stem cankers on Pinus tree species, which remains a threat to the forests.

The PTI-suppressing Avr2 effector from Fusarium oxysporum suppresses mono-ubiquitination and plasma membrane dissociation of BIK1

Plant pathogens use effector proteins to target host processes involved in pathogen perception, immune signalling, or defence outputs. Unlike foliar pathogens, it is poorly understood how root-invading pathogens suppress immunity. The Avr2 effector from the tomato root- and xylem-colonizing pathogen Fusarium oxysporum suppresses immune signalling induced by various pathogen-associated molecular patterns (PAMPs). It is unknown how Avr2 targets the immune system. Transgenic AVR2 Arabidopsis thaliana phenocopies mutants in which the pattern recognition receptor (PRR) co-receptor BRI1-ASSOCIATED RECEPTOR KINASE (BAK1) or its downstream signalling kinase BOTRYTIS-INDUCED KINASE 1 (BIK1) are knocked out. We therefore tested whether these kinases are Avr2 targets. Flg22-induced complex formation of the PRR FLAGELLIN SENSITIVE 2 and BAK1 occurred in the presence and absence of Avr2, indicating that Avr2 does not affect BAK1 function or PRR complex formation. Bimolecular fluorescence complementation assays showed that Avr2 and BIK1 co-localize in planta. Although Avr2 did not affect flg22-induced BIK1 phosphorylation, mono-ubiquitination was compromised. Furthermore, Avr2 affected BIK1 abundance and shifted its localization from nucleocytoplasmic to the cell periphery/plasma membrane. Together, these data imply that Avr2 may retain BIK1 at the plasma membrane, thereby suppressing its ability to activate immune signalling. Because mono-ubiquitination of BIK1 is required for its internalization, interference with this process by Avr2 could provide a mechanistic explanation for the compromised BIK1 mobility upon flg22 treatment. The identification of BIK1 as an effector target of a root-invading vascular pathogen identifies this kinase as a conserved signalling component for both root and shoot immunity.

Identification and Pathogenicity of Fusarium Isolated from Soybean in Poland

Fungi belonging to the Fusarium genus are commonly isolated from soybean plants and seeds but not all of them are pathogenic. The aim of this study was to compare the pathogenicity among different Fusarium isolates obtained from soybean plants with disease symptoms originating from an experimental field located in the southeast of Poland. Nineteen fungal isolates were selected for the pathogenicity assay, including eight isolates of F. oxysporum, six isolates of F. graminearum, four isolates of F. culmorum and one isolate of F. redolens. Species identification of these isolates was carried out using microscopic methods and sequencing of two genes: translation elongation factor 1-alpha (TEF1) and RNA polymerase second largest subunit (RPB2). To our knowledge, this is the first report of F. redolens being isolated from soybean in Europe. The pathogenicity test was set up by fungal inoculation of healthy soybean seeds of three cultivars: Abelina, Atlanta and Mavka. Symptoms were assessed seven days after inoculation. Disease area percentage of Fusarium inoculated seeds was significantly higher compared to uninoculated control. Nineteen isolates differed in their aggressiveness as the median disease area percentage ranged between 5.0 and 88.0% depending on isolate. The obtained isolates of four Fusarium species may be used in the future screening of soybean cultivars for resistance to these pathogens.

Quantitative Acetylome Analysis of Differentially Modified Proteins in Virulence-Differentiated Fusarium oxysporum f. sp. cucumerinum Isolates during Cucumber Colonization

Fusarium oxysporum f. sp. cucumerinum (Foc) is a prominent pathogen that adversely affects cucumber (Cucumis sativus) production. In the pathogen's parasitic lifestyle, the pathogenesis and virulence evolution may be regulated by lysine acetylation, as demonstrated in many living organisms. However, its specific function in Foc remains poorly understood. In this study, the acetylome profiles of a mild virulence strain (foc-3b) and its derived virulence-enhanced strain (Ra-4) were analyzed before and post-inoculation on cucumber plants. In total, 10,664 acetylation sites were identified corresponding to 3874 proteins, and 45 conserved acetylation motifs were detected. Through comparison of the acetylomes, numerous differentially lysine-acetylated proteins were enriched in energy metabolism and protein processing processes, indicating the critical role of lysine acetylation during the transition from the saprotrophic lifestyle to the parasitic lifestyle. Comparative acetylome analyses on the two virulence-differentiated strains revealed that several differentially lysine-acetylated proteins were involved in pathways of defense response and energy metabolism. Ra-4 showed enhanced energy metabolism compared to foc-3b. This indicates that robust metabolic activity is required to achieve high virulence and facilitating adaptive evolution. Additionally, faster host responses are supported by an ample energy supply enhancing virulence. Thus, lysine acetylation plays a crucial role in the pathogenesis and virulence evolution of Foc.

Establishment of the Recombinase Polymerase Amplification-Lateral Flow Dipstick Detection Technique for Fusarium oxysporum

Fusarium oxysporum causes crown rot, wilt, root rot, and many other major plant diseases worldwide. During the progression of strawberry crown rot disease, the pathogen is transmitted from the mother plant to the seedling through the stolon, with obvious characteristics of latent infection. Therefore, rapid and timely detection of F. oxysporum is important for efficient disease management. In this study, a recombinase polymerase amplification-lateral flow dipstick (RPA-LFD) detection technique was developed for the rapid detection of F. oxysporum on strawberry plants by targeting the CYP51C gene, which is unique to Fusarium spp. Because this RPA-LFD detection technique was highly specific to F. oxysporum, other Fusarium and non-Fusarium fungi were not detected. The optimal reaction temperature and time for this technique were 39°C and 8 min, respectively. The detection limit was 1 pg of F. oxysporum genomic DNA in a 50-μl reaction system. A total of 46 strawberry plants with or without crown rot symptoms collected from Jiande, Changxing, and Haining in Zhejiang Province were further assessed for F. oxysporum infection using both RPA-LFD and traditional tissue isolation techniques. The RPA-LFD test showed that 32 of the 46 strawberry plants tested were positive for F. oxysporum, while in the traditional isolation technique, F. oxysporum was isolated from 30 of the 46 strawberry plants. These results suggest that our established RPA-LFD method is rapid, sensitive, and highly specific in detecting F. oxysporum infection in strawberry plants.

The Signal Peptidase FoSpc2 Is Required for Normal Growth, Conidiation, Virulence, Stress Response, and Regulation of Light Sensitivity in Fusarium odoratissimum

Signal peptidase (SPase) is responsible for cleavage of N-terminal signal peptides in most secretory precursor proteins and many membrane proteins during maturation. In this study, we identified four components of the SPase complex (FoSec11, FoSpc1, FoSpc2, and FoSpc3) in the banana wilt fungal pathogen Fusarium odoratissimum. We proved that interactions exist among the four SPase subunits by bimolecular fluorescence complementation (BiFC) and affinity purification and mass spectrometry (AP-MS) assays. Among the four SPase genes, FoSPC2 was successfully deleted. FoSPC2 deletion caused defects in vegetative growth, conidiation, and virulence. Loss of FoSPC2 also affected the secretion of some pathogenicity-related extracellular enzymes, suggesting that SPase without FoSpc2 may have a lower efficiency in managing the maturation of the extracellular enzymes in F. odoratissimum. In addition, we found that the ΔFoSPC2 mutant had increased sensitivity to light, and the colonies of the mutant grew faster under all-dark conditions than under all-light conditions. We further observed that deletion of FoSPC2 affected expression of the blue light photoreceptor gene FoWC2, leading to cytoplasmic accumulation of FoWc2 under all-light conditions. Since FoWc2 has signal peptides, FoSpc2 may regulate the expression and subcellular localization of FoWc2 indirectly. Contrary to its response to light, the ΔFoSPC2 mutant displayed a significant decreased sensitivity to osmotic stress, and culturing the mutant under osmotic stress conditions restored both the localization of FoWc2 and light sensitivity of the ΔFoSPC2, suggesting that a cross talk between osmotic stress and light response pathways in F. odoratissimum and FoSpc2 takes part in these processes. IMPORTANCE In this study, we identified four components of SPase in the banana wilt pathogen Fusarium odoratissimum and characterized the SPase FoSpc2. Loss of FoSPC2 affected the secretion of extracellular enzymes, suggesting that SPase without FoSpc2 may have a lower efficiency in managing the maturation of the extracellular enzymes in F. odoratissimum. In addition, this is the first time that we have found a relationship between the SPase and fungal light response. Deletion of FoSPC2 resulted in decreased sensitivity to the osmotic stresses but with increased sensitivity to light. Continuous light inhibited the growth rate of the ΔFoSPC2 mutant and affected the cellular localization of the blue light photoreceptor FoWc2 in this mutant, but culturing the mutant under osmotic stress both restored the localization of FoWc2 and eliminated the light sensitivity of the ΔFoSPC2 mutant, suggesting that loss of FoSPC2 may affect a cross talk between the osmotic stress and light response pathways in F. odoratissimum.

Isolation and characterization of phosphate-solubilizing bacteria from rhizosphere of poplar on road verge and their antagonistic potential against various phytopathogens

BACKGROUND

Phosphate-solubilizing bacteria (PSB) can solubilize insoluble phosphate compounds and improve phosphate availability in soil. Road verges are important in urban landscaping, but the population structure of PSB and their ecological functions in the road verge soil is still unclear.

RESULTS

Twenty-one mineral PSB strains and 14 organic PSB strains were isolated from the rhizosphere of poplar on urban road verge. All the mineral PSB strains showed better solubilization to Ca3(PO4)2 than FePO4 or AlPO4. Among them, 7 strains showed high phosphate-solubilizing (PS) activities to Ca3(PO4)2 (150-453 mg/L). All the organic PSB strains displayed weak solubilization to lecithin. 16S rRNA gene-based phylogenetic analysis showed good species diversity of the PSB strains, which belongs to 12 genera: Bacillus, Cedecea, Cellulosimicrobium, Delftia, Ensifer, Paenibacillus, Pantoea, Phyllobacterium, Pseudomonas, Rhizobium, Sinorhizobium and Staphylococcus. Moreover, 8 PSB strains showed various degrees of growth inhibition against 4 plant pathogenic fungi, Fusarium oxysporum S1, F. oxysporum S2, Pythium deliense Meurs Z4, Phomopsis sp. AC1 and a plant pathogenic bacterium, Pectobacterium carotovorum TP1.

CONCLUSIONS

The results indicated that these PSB strains could perform multiple ecological functions on road verge. The development and application of bio-agents based on the strains would provide a new strategy for maintaining and improving the ecosystem stability of road verges.

Increased Conidia Production and Germination In Vitro Correlate with Virulence Enhancement in Fusarium oxysporum f. sp. cucumerinum

Cucumber plants commonly suffer from Fusarium wilt disease, which is caused by Fusarium oxysporum f. sp. cucumerinum (Foc). Although resistant cultivars assist with Fusarium wilt disease control, enhancement of the virulence of Foc has been identified after monoculture of wilt-resistant cultivars. To investigate the biological characteristics that contribute to the virulence evolution of Foc, a wildtype strain foc-3b (WT) and its virulence-enhanced variant Ra-4 (InVir) were compared in terms of their growth, reproduction, stress tolerance, and colonization in cucumber plants. The InVir strain showed similar culture characteristics on PDA media to the WT strain but produced significantly more conidia (>two fold), with a distinctly higher germination rate (>four fold) than the WT strain. The colony diameter of the InVir strain increased faster than the WT strain on PDA plates; however, the mycelia dry weight of the InVir was significantly lower (<70%) than that of the WT harvested from PDB. The InVir strain exhibited a significant increase in tolerance to osmolality (1 M NaCl, 1 M KCl, etc.). The GFP-labeled InVir strain propagated in the cucumber vascular faster than the WT strain. These results suggest that increased conidia production and germination in vitro may correlate with virulence enhancement in Fusarium oxysporum f. sp. cucumerinum. This study will provide an insight into its virulence evolution and help us understand the mechanisms underlying the evolutionary biology of F. oxysporum.

Rho2 involved in development, stress response and pathogenicity of Fusarium oxysporum

Rho GTPases regulate the activity of cell wall biosynthesis, actin assembly and polar cell secretion. However, the function of Rho GTPase in filamentous fungi is poorly understood. To understand the role of Rho2 GTPase in Fusarium oxysporum, which is one of root rot pathogens of Panax notoginseng, △rho2 mutant was constructed. Phenotypes of △rho2, including conidiation, germination of spores, stresses (osmotic-, cell membrane-, cell wall disturbing-, metal-, and high temperature-) tolerance and pathogenicity were analyzed. The results showed that the growth of △rho2 was destroyed under cell wall disturbing stress and high temperature stress, suggesting that Rho2 regulated the response of F. oxysporum to cell wall synthesis inhibitors and high temperature stress. Germination of spores and pathogenicity to P. notoginseng were reduced in △rho2 mutant. Western blot results showed that rho2 deletion increased the phosphorylation level of Mpk1. To identify genes regulated by Rho2, transcriptome sequencing was carried out. 2477 genes were identified as upregulated genes and 2177 genes were identified as downregulated genes after rho2 was deleted. These genes provide clues for further study of rho2 function.

Degradation of α-Subunits, Doa1 and Doa4, are Critical for Growth, Development, Programmed Cell Death Events, Stress Responses, and Pathogenicity in the Watermelon Fusarium Wilt Fungus Fusarium oxysporum f. sp. niveum

The ubiquitin-proteasome system (UPS) regulates protein quality or control and plays essential roles in several biological and biochemical processes in fungi. Here, we present the characterization of two UPS components, FonDoa1 and FonDoa4, in watermelon Fusarium wilt fungus, Fusarium oxysporum f. sp. niveum (Fon), and their biological functions. FonDoa1 localizes in both the nucleus and cytoplasm, while FonDoa4 is predominantly present in the cytoplasm. Both genes show higher expression in germinating macroconidia at 12 h. Deletion of FonDoa1 or FonDoa4 affects vegetative growth, conidiation, conidial germination/morphology, apoptosis, and responses to environmental stressors. FonDoa1, but not FonDoa4, positively regulates autophagy. The targeted disruption mutants exhibit significantly attenuated pathogenicity on watermelon due to defects in the infection process and invasive fungal growth. Further results indicate that the WD40, PFU, and PUL domains are essential for the function of FonDoa1 in Fon pathogenicity and environmental stress responses. These findings demonstrate the previously uncharacterized biological functions of FonDoa1 and FonDoa4 in phytopathogenic fungi, providing potential targets for developing strategies to control watermelon Fusarium wilt.

Dysfunctional Pro1 leads to female sterility in rice blast fungi

Although sexual reproduction is widespread in eukaryotes, some fungal species can only reproduce asexually. In the rice blast fungus Pyricularia (Magnaporthe) oryzae, several isolates from the region of origin retain mating ability, but most isolates are female sterile. Therefore, female fertility may have been lost during its spread from the origin. Here, we show that functional mutations of Pro1, a global transcriptional regulator of mating-related genes in filamentous fungi, is one cause of loss of female fertility in this fungus. We identified the mutation of Pro1 by backcrossing analysis between female-fertile and female-sterile isolates. The dysfunctional Pro1 did not affect the infection processes but conidial release was increased. Furthermore, various mutations in Pro1 were detected in geographically distant P. oryzae, including pandemic isolates of wheat blast fungus. These results provide the first evidence that loss of female fertility may be advantageous to the life cycle of some plant pathogenic fungi.

Graphene-Cu Nanocomposites Induce Tolerance against Fusarium oxysporum, Increase Antioxidant Activity, and Decrease Stress in Tomato Plants

The tomato crop is susceptible to various types of stress, both biotic and abiotic, which affect the morphology, physiology, biochemistry, and genetic regulation of plants. Among the biotic factors, is the phytopathogen Fusarium oxysporum f. sp. lycopersici (Fol), which can cause losses of up to 100%. Graphene-Cu nanocomposites have emerged as a potential alternative for pathogen control, thanks to their antimicrobial activity and their ability to induce the activation of the antioxidant defense system in plants. In the present study, the effect of the Graphene-Cu nanocomposites and the functionalization of graphene in the tomato crop inoculated with Fol was evaluated, analyzing their impacts on the antioxidant defense system, the foliar water potential (Ψ_h), and the efficiency of photosystem II (PSII). The results demonstrated multiple positive effects; in particular, the Graphene-Cu nanocomposite managed to delay the incidence of the "vascular wilt" disease and reduce the severity by 29.0%. This translated into an increase in the content of photosynthetic pigments and an increase in fruit production compared with Fol. In addition, the antioxidant system of the plants was improved, increasing the content of glutathione, flavonoids, and anthocyanins, and the activity of the GPX, PAL, and CAT enzymes. Regarding the impact on the water potential and the efficiency of the PSII, the plants inoculated with Fol and treated with the Graphene-Cu nanocomposite responded better to biotic stress compared with Fol, reducing water potential by up to 31.7% and Fv/Fm levels by 32.0%.

Identification and characterization of pathogens causing saffron corm rot in China

Corm rot is the most important disease of saffron, for which fungi from several genus such as Fusarium spp. Penicillium spp. and Botrytis spp., have been previously reported to be the pathogens. In this research, we used a combination of amplicon sequencing and traditional isolation methods to identify the causal agents, main infection source. The diversity of microbial communities in diseased saffron corms and soil decreased significantly compared with healthy corms and soil. The contents of Penicillium and Botrytis in healthy and diseased corms were similarly high, indicating that them were not directly related to the occurrence of corm rot. But the relative abundance of Fusarium, Cadophora and Fusicolla were significantly higher in the diseased corms than healthy ones. The abundance of Fusarium increased, while the abundance of Oidiodendron, Paraphaeosphaeria and the endophytic beneficial bacteria Pseudomonas decreased, which may relate to the occurrence of the disease. The co-occurrence network diagram showed that the correlation between fungal and bacterial communities was mainly positive. Plant pathogens were relatively abundant in the diseased soil, according to functional gene prediction. At the same time, we also collected 100 diseased corms from the fields in Jiande, where is known as the "hometown of saffron." All isolated pathogenic strains were identified as Fusarium oxysporum through morphological observation and phylogenetic tree analysis of ITS, Tef-1α and β-tubulin. To better clarify the biological characteristics of F. oxysporum, we cultured the isolates at different temperatures and pH values. The optimum temperature for mycelial growth and sporulation was 25°C, pH 6，carbon sources sorbitol and nitrogen sources, peptone. In short, our results suggests that F. oxysporum was the pathogen causing corm rot in Jiande and corms other than soils are the main primary infection source. These new understanding of saffron corm rot will provide the theoretical basis for its better and efficiently management.

Group I Intron as a Potential Target for Antifungal Compounds: Development of a Trans-Splicing High-Throughput Screening Strategy

The search for safe and efficient new antifungal compounds for agriculture has led to more efforts in finding new modes of action. This involves the discovery of new molecular targets, including coding and non-coding RNA. Rarely found in plants and animals but present in fungi, group I introns are of interest as their complex tertiary structure may allow selective targeting using small molecules. In this work, we demonstrate that group I introns present in phytopathogenic fungi have a self-splicing activity in vitro that can be adapted in a high-throughput screening to find new antifungal compounds. Ten candidate introns from different filamentous fungi were tested and one group ID intron found in F. oxysporum showed high self-splicing efficiency in vitro. We designed the Fusarium intron to act as a trans-acting ribozyme and used a fluorescence-based reporter system to monitor its real time splicing activity. Together, these results are opening the way to study the druggability of such introns in crop pathogen and potentially discover small molecules selectively targeting group I introns in future high-throughput screenings.

Antifungal activity of volatile and non-volatile metabolites of endophytes of Chloranthus elatior Sw

Agriculture crops that have fungal infections suffer significant economic losses and reduced crop output. Chemical fungicides are used to tackle the problem, although this has additional detrimental side effects. There is an urgent need for safe and novel antifungals. Volatiles from plant-beneficial endophytic fungi are considered promising alternatives for the biological control of fungal pathogens as a sustainable approach in an agroecosystem. In the present investigation, a volatile-emitting sterile endophytic fungus, Diaporthe sp. CEL3 with bio-fumigation activity, was isolated from leaves of the ethnomedicinal plant Chloranthus elatior Sw., collected from the Passighat forest of North-East India. The camphor odor volatiles of CEL3 showed an inhibitory effect against eight fungal pathogens in vitro and minimized the infections of Monilinia fructicola, a causal agent of cherry fruit rot, in VOC-exposed cherry fruits. Rhizoctonia solani, Botrytis cinerea, Pythium ultimum, and M. fructicola were maximally inhibited up to 51.5%, 55.8%, 61.9%, and 78.5%, respectively, in comparison to control by the volatiles. Another isolate, CEL7, identified as Curvularia sp., synthesized non-volatile, soluble antifungal metabolites in its cell-free extracts and exhibited antifungal action. Bioassay-guided fractionation revealed the presence of imidazole compounds- (2-aminoethyl)-1H-imidazole-2-carbaldehyde, Pyrazole 4, 5 imidazole, 1-formyl 3-ethyl, phenol compounds-Phenol, 4-[2-(methylamino) ethyl]-, 6-Nitro-3-chlorophenol, Phenol, 2,4,6-tri-tert-butyl-, etc., in the cell-free extracts, with a MIC value of 250-2,000 µg ml-1. Optimum VOC emission was achieved in a modified PDA medium with instantly smashed potato (150 g L-1), dextrose (20 g L-1), wheat husk (20 g L-1), and yeast extract (20 g L-1), with additional salts. Interestingly, endophytic CEL3 emitted different types of volatiles, and trans-verbenol (32.25%), geraniol (30.32%), trans-ocimenol (12.90%), and mentha-4,8-diene (5.16%) were the prime ones. These VOCs cause lethal leakage of protein and necessary intracellular molecules from the fungal pathogens. Thus, CEL3 could potentially be used as a bio-fumigating agent to control post-harvest infections caused by fungal pathogens. This study opens a new approach to the use of endophytic fungi in biocontrol.

Pathogen Stopping and Metabolism Modulation Are Key Points to Linum usitatissimum L. Early Response against Fusarium oxysporum

Fusarium oxysporum is the one of the most common and impactful pathogens of flax. Cultivars of flax that show resistance to this pathogen have previously been identified. To better understand the mechanisms that are responsible for this resistance, we conducted time-lapse analysis of one susceptible and one resistant cultivar over a two-week period following infection. We also monitored changes in some metabolites. The susceptible cultivar showed a strong onset of symptoms from 6 to 8 days after inoculation, which at this time point, was associated with changes in metabolites in both cultivars. The resistant cultivar maintained its height and normal photosynthetic capacity but showed a reduced growth of its secondary stems. This resistance was correlated with the containment of the pathogen at the root level, and an increase in some metabolites related to the phenylpropanoid pathway.

Loss of Phosphomannose Isomerase Impairs Growth, Perturbs Cell Wall Integrity, and Reduces Virulence of Fusarium oxysporum f. sp. cubense on Banana Plants

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) causes Fusarium wilt of banana, necessitating urgent measures to control this disease. However, the molecular mechanisms underlying Foc TR4 virulence remain elusive. Phosphomannose isomerase is a key enzyme involved in the biosynthesis of GDP mannose, an important precursor of fungal cell walls. In this study, two phosphomannose isomerases were identified in the Foc TR4 genome, of which only Focpmi1 was highly expressed throughout all developmental stages. Generated null mutants in Foc TR4 showed that only the ΔFocpmi1 mutant required exogenous mannose for growth, indicating that Focpmi1 is the key enzyme involved in GDP mannose biosynthesis. The Focpmi1 deficient strain was unable to grow without exogenous mannose and exhibited impaired growth under stress conditions. The mutant had reduced chitin content in its cell wall, rendering it vulnerable to cell wall stresses. Transcriptomic analysis revealed up- and down-regulation of several genes involved in host cell wall degradation and physiological processes due to the loss of Focpmi1. Furthermore, Focpmi1 was also found to be crucial for Foc TR4 infection and virulence, making it a potential antifungal target to address the threats posed by Foc TR4.

A Novel Effector, FSE1, Regulates the Pathogenicity of Fusarium oxysporum f. sp. cubense Tropical Race 4 to Banana by Targeting the MYB Transcription Factor MaEFM-Like

Phytopathogenic fungi secretes a range of effectors to manipulate plant defenses. Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is a soil-borne pathogen that causes destructive banana wilt disease. Understanding the molecular mechanisms behind Foc TR4 effectors and their regulation of pathogenicity is helpful for developing disease control strategies. In the present study, we identified a novel effector, Fusarium special effector 1 (FSE1), in Foc TR4. We constructed FSE1 knock-out and overexpression mutants and investigated the functions of this effector. In vitro assays revealed that FSE1 was not required for vegetative growth and conidiation of Foc TR4. However, inoculation analysis of banana plantlets demonstrated that knock-out of FSE1 increased the disease index, while overexpression of FSE1 decreased it. Microscope analysis suggested that FSE1 was distributed in the cytoplasm and nuclei of plant cells. Furthermore, we identified an MYB transcription factor, MaEFM-like, as the target of FSE1, and the two proteins physically interacted in the nuclei of plant cells. In addition, Transient expression of MaEFM-like induced cell death in tobacco leaves. Our findings suggest that FSE1 is involved in the pathogenicity of Foc TR4 by targeting MaEFM-like.

Protocol for histological analysis of the interaction Vanilla planifolia - Fusarium oxysporum f. sp. vanillae

Fusarium oxysporum f. sp. vanillae (Fov) is the main phytosanitary problem of Vanilla planifolia, invading the root and causing the rotting of up to 80% of the plants. The histological process is used to study the morphological characteristics of the tissues of interest and published a protocol to check Fov-V. planifolia interaction that was not reproducible under our conditions, so the study aimed to adapt a procedure that allows differential analysis of the mechanism of Fov invasion in V. planifolia by confocal microscopy. The bioassays consisted of analyzing Fov-infected roots. The experimental design consisted of three replicates evaluated at 12, 24, 36, 48, 60 and 72 hours post-inoculation. Roots without inoculum were used as controls. The samples were fixed in paraformaldehyde and 4% sucrose (PBS). Subsequently, the tissues were dehydrated by a combination of alcohols at different concentrations. The cuts were made with a microtome. The sections were observed under a Leica confocal microscope with a 63X objective with ap. No. 1.4, plus immersion oil; excitation lines: 405, 488, 532. The FAA + kerosene method was the procedure that allowed complete tissue sections. Keywords: Fusariosis, Vanilla, interaction.

Conservation and Expansion of Transcriptional Factor Repertoire in the Fusarium oxysporum Species Complex

The Fusarium oxysporum species complex (FOSC) includes both plant and human pathogens that cause devastating plant vascular wilt diseases and threaten public health. Each F. oxysporum genome comprises core chromosomes (CCs) for housekeeping functions and accessory chromosomes (ACs) that contribute to host-specific adaptation. This study inspects global transcription factor profiles (TFomes) and their potential roles in coordinating CC and AC functions to accomplish host-specific interactions. Remarkably, we found a clear positive correlation between the sizes of TFomes and the proteomes of an organism. With the acquisition of ACs, the FOSC TFomes were larger than the other fungal genomes included in this study. Among a total of 48 classified TF families, 14 families involved in transcription/translation regulations and cell cycle controls were highly conserved. Among the 30 FOSC expanded families, Zn2-C6 and Znf_C2H2 were most significantly expanded to 671 and 167 genes per family including well-characterized homologs of Ftf1 (Zn2-C6) and PacC (Znf_C2H2) that are involved in host-specific interactions. Manual curation of characterized TFs increased the TFome repertoires by 3% including a disordered protein Ren1. RNA-Seq revealed a steady pattern of expression for conserved TF families and specific activation for AC TFs. Functional characterization of these TFs could enhance our understanding of transcriptional regulation involved in FOSC cross-kingdom interactions, disentangle species-specific adaptation, and identify targets to combat diverse diseases caused by this group of fungal pathogens.

Pathogenic fungi neutralize plant-derived ROS via Srpk1 deacetylation

In response to infection, plants can induce the production of reactive oxygen species (ROS) to restrict pathogen invasion. In turn, adapted pathogens have evolved a counteracting mechanism of enzymatic ROS detoxification, but how it is activated remains elusive. Here, we show that in the tomato vascular wilt pathogen Fusarium oxysporum f. sp. lycopersici (Fol) this process is initiated by deacetylation of the FolSrpk1 kinase. Upon ROS exposure, Fol decreases FolSrpk1 acetylation on the K304 residue by altering the expression of the acetylation-controlling enzymes. Deacetylated FolSrpk1 disassociates from the cytoplasmic FolAha1 protein, thus enabling its nuclear translocation. Increased accumulation of FolSrpk1 in the nucleus allows for hyperphosphorylation of its phosphorylation target FolSr1 that subsequently enhances transcription of different types of antioxidant enzymes. Secretion of these enzymes removes plant-produced H₂ O₂ , and enables successful Fol invasion. Deacetylation of FolSrpk1 homologs has a similar function in Botrytis cinerea and likely other fungal pathogens. These findings reveal a conserved mechanism for initiation of ROS detoxification upon plant fungal infection.