Fire blight, caused by Erwinia amylovora (EA), is a devastating bacterial disease affecting pome fruit trees with significant economic impacts worldwide. Effective management of the disease is challenging due to the rapid epiphytic growth of EA on stigmas and its subsequent entry into the hypanthium, creating an exceptionally narrow temporal window for blossom blight intervention. Successful management strongly depends on accurate prediction of infection risk and timely applications of preventive measures. This review examines the history of fire blight forecasting, from early empirical and thermal indices to advanced, biologically informed mechanistic models. We focus on two globally used, empirically derived, mechanistic fire blight forecasting models, i.e. MARYBLYT and CougarBlight. Evaluations across North America, Europe, and the Middle East confirm both models capture key blossom blight drivers, yet the accuracy of prediction remains regionally inconsistent. These inconsistencies arise in part from the models’ inability to accurately capture EA growth on apple stigmas under the complex microclimatic conditions of the orchard, where interactions between environment factors, host and pathogen occur. We critically evaluate these models by examining their biological assumptions, design frameworks, and data requirements, while assessing regional variations in their performance. We also highlight key limitations and propose future directions to improve prediction accuracy. This review underscores the critical need for next-generation forecasting models to enhance predictive accuracy and enable more effective disease management strategies.

The fire blight pathogen Erwinia amylovora is genetically homogeneous but exhibits substantial variations in virulence, motility, and amylovoran production. A possible explanation for these functional diversities could be due to large chromosomal inversions (LCIs), structural rearrangements associated with ribosomal RNA (rrn) operons. This study investigated the distribution of LCI types in E. amylovora populations from Washington state (WA) and their associated phenotypic diversities. A total of 191 isolates collected from WA between 2022 and 2024 were analyzed using PCR-based molecular markers targeting rrn operons. These isolates were classified into four most prevalent LCI types: Ea1189, CFBP1430, Ea273, and Ea401. Temporal analysis revealed diversity of LCI occurrence in different years, with up to four LCI types co-occurring within a single orchard in 2024. Phenotypic assays demonstrated significant differences among the isolates of the LCI types in amylovoran production and virulence. Differences in motility and disease severity development further emphasized the diversity among isolates even within each LCI type. Overall, our findings showed the primary population structure of E. amylovora in WA and highlighted measurable functional variations within the E. amylovora population. This study also demonstrated that multiple LCI types could coexist in a single orchard, highlighting that chromosomal structural variations could shape E. amylovora population diversity, adaptation, and pathogenic potential, which might help understand fire blight epidemiology and pathogen evolution.

Eight potential biocontrol bacteria were isolated from diseased apple (Malus domestica) tissues. Here, we report high-quality complete genome sequences for the eight isolates. These data might help in understanding the genetic basis of biocontrol activity, strain compatibility, and ecological adaptation of biocontrol agents for fire blight disease management.

Bacterial canker disease (BCD), mainly caused by Pseudomonas syringae pv. syringae (Pss) and P. amygdali pv. morsprunorum (Pam), threatens the Pacific Northwest (PNW) cherry industry. One major cause of young tree death in the PNW is heading-cut infections by Pseudomonas in newly established orchards. While copper has long been used for cut-wound protection, copper resistance in pseudomonads is widespread in the PNW. This study evaluated alternative chemicals and cultural strategies for management of cut-wound infections. Lime sulfur (LS) exhibited concentration- and time-dependent bacteriostatic activity in vitro, with 5-10% LS efficiently reducing Pss and Pam populations within 6h. Clove oil at concentrations equal to or above 0.0625% completely eliminated both pathogens within 30 s. To evaluate the efficacy of alternative chemicals, field trials in 2024 revealed that kasugamycin and oxytetracycline significantly reduced canker development when heading-cuts were performed under hot, dry weather conditions as compared with copper- and latex-paint-based treatments. When heading-cuts were done under cool, humid conditions, oxytetracycline, Actigard, and kasugamycin exhibited better cut-wound protection in terms of canker length. Canker development was more rapid and occurred at a higher frequency in trees pruned under cool, humid conditions compared to those pruned during hot, dry conditions. In 2025 field trials, kasugamycin (Kasumin) again suppressed canker progression, while addition of Vacciplant or additional chemical treatment offered no benefit. Furthermore, when plant tissues were removed at least 12.7 cm below visible cankers, no pathogen can be recovered. Our results indicate that chemical application and weather conditions during heading cut might be crucial in preventing cut-wound pseudomonads infection.

Erwinia amylovora is one of the most economically impactful plant pathogens worldwide. Pruning infected shoots and/or cankers throughout the season is commonly used to reduce the amount of inoculum present in the field. However, if the infection is not removed completely or pruning tools are not disinfected thoroughly, cutting wound infection can develop and spread, leading to tree death. Copper, a widely used chemical with bactericidal activity, is commonly used to manage fire blight. In this study, we investigated the efficacy of copper alone and/or mixed with latex paint to protect cut wounds from infection. Our results showed that copper itself and latex paint can provide some protection against E. amylovora infection when applied directly to cut wounds prior to inoculation. A 55–70

Most damage associated with fire blight disease (Erwinia amylovora) is due to blossom blight, so less research has been dedicated to shoot infections. Current control of shoot trauma blight, associated with wind or hail damage, relies on copper and antibiotics, yet sustainable alternatives are needed. This study evaluated the efficacy of chitosan, rhamnolipids, and caprylic acid against shoot trauma blight. We demonstrated the antimicrobial activity of all three compounds in vitro and optimized a host inoculation method mimicking high-infection pressure conditions. Caprylic acid, with high antimicrobial capacity in vitro, exhibited high phytotoxicity at effective bactericidal concentrations and provided no disease control in plants at nonphytotoxic concentrations. The efficacy of commercial chitosan-based products was dependent on product formulation. Only one of the three tested commercial products provided consistent control efficacy and/or symptom reduction levels comparable to those of antibiotics, copper, and/or acibenzolar-S-methyl in two greenhouse trials under high infection pressure. Rhamnolipids were effective at reducing symptom severity in two independent greenhouse assays and were the only treatment with significant effects in a field trial. Realtime PCR results showed that treatments with chitosan activated salicylic acid (SA)-dependent gene expression, whereas rhamnolipids induced genes linked to both SA- and jasmonic acid-dependent responses. Moreover, rhamnolipids enhanced kasugamycin and streptomycin activity in vitro, indicating their potential as coadjuvants for enhancing antibiotic activity at lower concentrations. Overall, our findings provide preliminary data for the implementation of these treatments in shoot trauma blight management, potentially useful under moderate or low infection pressure conditions.

IntroductionFire blight, caused by Erwinia amylovora, is a devastating disease of apples and pears. Limitations in current control strategies using antibiotics and copper demand for more sustainable alternatives . This study aimed to evaluate the potential of 13 microorganisms (12 bacteria, 1 yeast) co-isolated with E. amylovora from symptomatic apple tissues as biocontrol agents (BCAs) and determine how environmental conditions and ecological interactions influence their efficacy against the pathogen.MethodsWe optimized an in vitro agar plug assay to determine antagonistic activities of microorganisms under different environmental conditions. We utilized ex vivo assays on detached fruitlets to determine the efficacies of BACs. Bliss independence and best single agent frameworks were used to identify BAC helpers and hinderers.ResultsIn vitro agar plug assays revealed that antagonistic activity of these microbes was enhanced by environmental factors, including minimal media, acidic pH (6.0), lower temperature (22°C), and specific carbon sources (fructose and glucose), which significantly enhanced their pathogen inhibition abilities. Ex vivo assays on detached fruitlets demonstrated that preventive application of BCAs was more effective at reducing disease symptoms than a co-inoculation (curative) regime. Most combinations of antagonists reduced infection rates, with combinations containing Erwinia sp. 2186 achieving the highest disease suppression. Net interaction analysis using Bliss independence and best single agent frameworks identified biocontrol helper and hinderer organisms. As an example, Rahnella sp. EL51 and Pseudomonas sp. 2180 acted to synergistically enhance or antagonistically decrease disease suppression in paired treatments, respectively. Population dynamics of the top-performing pair (Erwinia sp. 2186 plus Rahnella sp. EL51) indicated a link between disease suppression, sustained BCA presence, bacteriostatic effects on E. amylovora populations and medium acidification.ConclusionThese findings underscore the importance of ecological interactions and environmental effects in developing biocontrol strategies against E. amylovora.

The phytopathogenic bacterium Erwinia amylovora is responsible for causing fire blight, a devastating disease affecting rosaceous plants, including apples and pears. E. amylovora strains exhibit differences in virulence depending on the genetic resistance status of the host and environmental factors. While genetic variations among E. amylovora strains are known to contribute to their genetic diversity, host range and biology, the impact of large chromosomal rearrangements on key bacterial phenotypes like disease aggressiveness is understudied. In order to investigate the relationship between large chromosomal inversions (LCIs) and fire blight aggressiveness of E. amylovora strains, we screened 16 E. amylovora isolates for their fire blight aggressiveness on immature Bartlett pears and continued with de novo genome sequencing of these strains originating from North America to characterise the association of detected LCIs with disease aggressiveness. The immature Bartlett pear assay showed significant differences in fire blight aggressiveness between the strains. Genome sequence comparison showed an average of 68 insertions, 11,166 single-nucleotide polymorphisms (SNPs), and 10,773 insertions/deletions (indels) across the 16 isolates when compared to the reference strain Ea1189. Additionally, eight distinct LCIs were identified among sequenced isolates. All isolates carried the ubiquitous pEA29 plasmid, whereas EaRJO001 has an additional pEA27 plasmid. Although E. amylovora strains exhibited significant differences in fire blight aggressiveness, their association with LCIs remains unclear.

Fire blight, caused by Erwinia amylovora, is a devastating disease that affects apples and pears, leading to significant economic losses worldwide. The disease is typically managed through a combination of biological, cultural, and chemical strategies. Due to the emergence of antibiotic resistance and concerns regarding chemical residues, there is an urgent need for new bactericides that are both highly effective and low in toxicity. Recently, the Ministry of Agriculture and Rural Affairs of China approved the registration of a new bactericide, benziothiazolinone also known as 1,2-Benzisothiazol-3-one. The assessment of benziothiazolinone demonstrated an EC50 value of 0.48 µg/mL against E. amylovora BZ16 after a 10-hour inoculation period, and 0.67 µg/mL after 16 h. Furthermore, benziothiazolinone displays a broad antimicrobial spectrum against various microorganisms, including bacteria, fungi, and oomycetes, as evidenced by its EC50 values. Prolonged exposure to benziothiazolinone was found to enhance the production of amylovoran in the E. amylovora strain BZ16BITR; however, this treatment significantly diminished the pathogenicity of the strain. Resistance risk analysis indicates that E. amylovora has a low risk of developing resistance to benziothiazolinone. Results from two-year field trials demonstrated that benziothiazolinone could significantly reduce the disease incidence of fire blight. Compared to the streptomycin control, the application of benziothiazolinone exhibited excellent efficacy, achieving over 80

Fusarium crown rot (FCR), caused by Fusarium spp., is a devastating disease in wheat growing areas. Previous studies have shown that FCR is caused by co-infection of F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides in Hubei Province, China. In this study, a method was developed to simultaneously detected DNAs of F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides that can efficiently differentiate them. Whole genome sequence comparison of these four Fusarium spp. was performed and a 20 bp sequence was designed as an universal upstream primer. Specific downstream primers of each pathogen was also designed, which resulted in a 206, 482, 680, and 963 bp amplicon for each pathogen, respectively. Multiplex PCR specifically identified F. graminearum, F. pseudograminearum, F. proliferatum and F. verticillioides but not from other 46 pathogens, and the detection limit of target pathogens is about 100 pg/μl. Moreover, we accurately determined the FCR pathogen species in wheat samples using the optimized multiplex PCR method. These results demonstrate that the multiplex PCR method established in this study can efficiently and rapidly identify F. graminearum, F. pseudograminearum, F. proliferatum, and F. verticillioides, which should provide technical support for timely and targeted prevention and control of FCR.

Fusarium graminearum is an important fungal pathogen causing Fusarium head blight (FHB) in wheat and other cereal crops worldwide. Due to lack of resistant wheat cultivars, FHB control mainly relies on application of chemical fungicides. Both fludioxonil (a phenylpyrrole compound) and phenamacril (a cyanoacrylate fungicide) have been registered for controlling FHB in China, however, fludioxonil-resistant isolates of F. graminearum have been detected in field. To evaluate the potential risk of dual resistance of F. graminearum to both compounds, fludioxonil and phenamacril dual resistant (DR) mutants of F. graminearum were obtained via fungicide domestication in laboratory. Result showed that resistance of the DR mutants to both fludioxonil and phenamacril were genetically stable after sub-cultured for ten generations or stored at 4 °C for 30 days on fungicide-free PDA. Cross-resistance assay showed that the DR mutants remain sensitive to other groups of fungicides, including carbendazim, tebuconazole, pydiflumetofen, and fluazinam. In addition, the DR mutants exhibited defects in mycelia growth, conidiation, mycotoxin deoxynivalenol (DON) production, and virulence Moreover, the DR mutants displayed increased sensitivity to osmotic stress. Sequencing results showed that amino acid point mutations S217L/T in the myosin I protein is responsible for phenamacril resistance in the DR mutants. Our results indicate that mutations leading to fludioxonil and phenamacril dual resistance could result in fitness cost for F. graminearum. Our results also suggest that the potential risk of F. graminearum developing resistance to both fludioxonil and phenamacril in field could be rather low, which provides scientific guidance in controlling FHB with fludioxonil and phenamacril.

Mycotoxin deoxynivalenol (DON) produced by the Fusarium graminearum complex is highly toxic to animal and human health. During DON synthesis, the endoplasmic reticulum (ER) of F. graminearum is intensively reorganized, from thin reticular structure to thickened spherical and crescent structure, which was referred to as "DON toxisome". However, the underlying mechanism of how the ER is reorganized into toxisome remains unknown. In this study, we discovered that overproduction of ER-localized DON biosynthetic enzyme Tri4 or Tri1, or intrinsic ER-resident membrane proteins FgHmr1 and FgCnx was sufficient to induce toxisome-shaped structure (TSS) formation under non-toxin-inducing conditions. Moreover, heterologous overexpression of Tri1 and Tri4 proteins in non-DON-producing fungi F. oxysporum f. sp. lycopersici and F. fujikuroi also led to TSS formation. In addition, we found that the high osmolarity glycerol (HOG), but not the unfolded protein response (UPR) signaling pathway was involved in the assembly of ER into TSS. By using toxisome as a biomarker, we screened and identified a novel chemical which exhibited high inhibitory activity against toxisome formation and DON biosynthesis, and inhibited Fusarium growth species-specifically. Taken together, this study demonstrated that the essence of ER remodeling into toxisome structure is a response to the overproduction of ER-localized DON biosynthetic enzymes, providing a novel pathway for management of mycotoxin contamination.

In 2023, an outbreak of bacterial canker disease (BCD) in sweet cherry orchards caused significant economic losses to growers and nurseries in the Pacific Northwest, USA (Fig. S1). The cherry industry in Washington State alone is valued at over $800 million (USDA NASS, 2022). BCD poses a recurring threat to the state’s sweet cherry [Prunus avium (L.) L.] orchards, especially young and newly planted orchards. Three Pseudomonas species, including P. syringae pv. syringae (Pss), P. amygdali pv. morsprunorum (Pam) (formerly P. syringae pv. morsprunorum Race 1, Psm1), and P. avellanae pv. morsprunorum (formerly P. syringae pv. morsprunorum Race 2, Psm2), have been reported to be associated with BCD in sweet cherries (Hulin et al. 2019). While Pss is widely prevalent in the United States, Pam has only been reported in Michigan (Renick et al., 2008) as well as in Europe, Central America, South Africa and Australia (Hulin et al. 2019) . In 2023, we surveyed more than 60 cherry orchards and collected hundreds of canker samples from newly planted up to 8-year-old trees. BCD prevalence ranged from 40-100% in cherry orchards, leading to the removal of hundreds of thousands of trees. Affected cherry trees exhibited characteristic bacterial canker symptoms, including dead bud, canker, and gummosis (Fig. S1). Bacteria were isolated from canker tissues or ooze on King’s B (KB) agar plates (King et al., 1954) and more than 300 fluorescent Pseudomonas isolates were obtained from 12 symptomatic sweet cherry cultivars. PCR results using Pss- and Pam- specific primers (SyrB and Psm1, Table S1) (Sorensen et al., 1998; Kałużna et al., 2016) revealed that 91.9% and 8% isolates were tested positive for SyrB and Psm1, indicating that these isolates potentially belong to Pss and Pam, respectively. Pathogenicity tests using immature cherries cv. Sentina showed that all isolates caused typical necrotic lesions and could be re-isolated and re-identified as Pss and Pam, thus completing Koch’s postulates. The identity of three Pam representative isolates (S79, S158, S202) was further confirmed by comparing gyrD and rpoD housekeeping genes as well as 16S rRNA gene sequence with other Pam strains in GenBank (Parkinson et al., 2010; Gomila et al., 2017). Blast searches against GenBank using gyrB (GenBank accession numbers PP357444-PP357446), rpoD (PP357447-PP357449) and 16S rRNA (GenBank accession numbers PP421223-PP421225) gene sequences, ranging from 520 to 859bp, matched those of the Pam isolates (GenBank accession numbers CP026558 or PP218075) with 100% homology and 100% query coverage, further indicating that these isolates are indeed Pam. This represents the first documented record of Pam causing BCD in the Pacific Northwest, USA, suggesting the complexity of the disease, which underscores the need for effective management strategies for cherry growers in the region.

BACKGROUND: Fusarium head blight (FHB) caused by Fusarium graminearum species complex (FGSG) remains a major challenge to cereal crops and resistance to key fungicides by the pathogen threatens control efficacy. Pydiflumetofen, a succinate dehydrogenase inhibitor, and phenamacril, a cyanoacrylate fungicide targeting myosin I, have been applied to combat this disease. Nonetheless, emergence of pydiflumetofen resistance in a subset of field isolates alongside laboratory-induced facile generation of phenamacril-resistant isolates signals a critical danger of resistance proliferation. RESULTS: Our study investigates the development of dual resistance to these fungicides in F. graminearum. Utilizing pydiflumetofen-resistant (Py (R)) and -sensitive (Py-S) isolates, we obtained dual-resistant (Py (R) Ph (R)) and phenamacril-resistant ((PyPh)-Ph-S (R)) mutants on potato sucrose agar containing phenamacril. Mutation rates for phenamacril resistance were comparable between pydiflumetofen-resistant and -sensitive isolates, implying independent pathways for resistance development. The mutants compromised in fungal growth, competitive viability and deoxynivalenol production, suggesting fitness penalties for the dual-resistant mutants. However, no cross-resistance was found with tebuconazole or fludioxonil. In addition, we characterized four critical amino acid changes (S217L, C423R, K537T, E420G) in the Myo1 that were verified to confer phenamacril resistance in F. graminearum. CONCLUSION: This research indicates the possibility of resistance development for both pydiflumetofen and phenamacril in F. graminearum and emphasizes the need for fungicide resistance management for FHB. (c) 2024 Society of Chemical Industry.

Fusarium fujikuroi, the causal agent of rice bakanae disease (RBD), contains five succinate dehydrogenase (Sdh) subunits: FfSdhA, FfSdhB, FfSdhC1, FfSdhC2, and FfSdhD. However, the role of these subunits in regulating sensitivity to succinate dehydrogenase inhibitors (SDHIs) is largely unknown. Here, we conducted targeted gene disruption and phenotypic assays for all Sdh subunits and found that the deletion mutants of FfSdhA, FfSdhB, and FfSdhD exhibited severe defects in hyphal growth, conidiation, virulence, and sensitivity to CaCl2 and oxidative stresses. To a lesser extent, the mycelial growth rate and conidial production of ΔFfSdhC1 were also decreased as compared to those of the wild-type strain JS16. In addition, fungicide sensitivity assays showed that deletion of FfSdhA, B, C1, or D led to decreased sensitivity to all SDHIs tested. Unexpectedly, we were unable to obtain a FfSdhC1 + C2 double mutant and further found significant up-regulation of FfSdhC2 in ∆FfSdhC1, indicating that FfSdhC1 and -C2 might be essential for fungal growth although the FfSdhC2 deletion mutant was indistinguishable from the wild-type strain. These findings provide useful information for enhancing our understanding of the biological functions of the Sdh subunits in pathogenic fungi.

Bacterial-fungal interactions are widespread in nature.We observed that pear orchards affected by Cytospora pyri(formerly Valsa pyri)were often accompanied with Erwinia amylovora.However,the relationship of the two pathogens was unclear.The objective of this study was to determine whether the synergistic effect exists between E.amylovora and C.pyri.We first analyzed the coexistence frequencies of E.amylovora and C.pyri in pear trees.Virulence of the two pathogens,growth,physical interactions,amylovoran production,and expression of genes for amylovoran biosynthesis were conducted.Our results showed that E.amylovora and C.pyri could coexist on the same lesion and caused much more severe disease.We also found that E.amylovora could physically attach to C.pyri and the expression of amylovoran biosynthesis genes were up-regulated with fungal metabolite treatment.These results indicate that E.amylovora and C.pyri can cooperatively interact,which provides C.pyri with an opportunity to promote bacterial dispersal and production of virulence factor in E.amylovora.

Erwinia amylovora is a relatively homogeneous species with low genetic diversity at the nucleotide level. However, phenotypic differences and genomic structural variations among E. amylovora strains have been documented. In this study, we identified 10 large chromosomal inversion (LCI) types in the Spiraeoideae-infecting (SI) E. amylovora strains by combining whole genome sequencing and PCR-based molecular markers. It was found that LCIs were mainly caused by homologous recombination events among seven rRNA operons (rrns) in SI E. amylovora strains. Although ribotyping results identified inter- and intra-variations in the internal transcribed spacer (ITS1 and ITS2) regions among rrns, LCIs tend to occur between rrns transcribed in the opposite directions and with the same tRNA content (tRNA-Glu or tRNA-Ile/Ala) in ITS1. Based on the LCI types, physical/estimated replichore imbalance (PRI/ERI) was examined and calculated. Among the 117 SI strains evaluated, the LCI types of Ea1189, CFBP1430, and Ea273 were the most common, with ERI values at 1.31, 7.87, and 4.47°, respectively. These three LCI types had worldwide distribution, whereas the remaining seven LCI types were restricted to North America (or certain regions of the United States). Our results indicated ongoing chromosomal recombination events in the SI E. amylovora population and showed that LCI events are mostly symmetrical, keeping the ERI less than 15°. These findings provide initial evidence about the prevalence of certain LCI types in E. amylovora strains, how LCI occurs, and its potential evolutionary advantage and history, which might help track the movement of the pathogen.

AIMS:The posttranscriptional regulator CsrA regulates many cellular processes, including stress responses in diverse bacteria. However, the role of CsrA in multidrug resistance (MDR) and biocontrol activity in Lysobacter enzymogenes strain C3 (LeC3) remains unknown.METHODS AND RESULTS:In this study, we demonstrated that deletion of the csrA gene resulted in the initial slow growth of LeC3 and reduced its resistance to multiple antibiotics, including nalidixic acid (NAL), rifampicin (RIF), kanamycin (Km), and nitrofurantoin (NIT). Loss of the csrA gene also reduced its ability in inhibiting hypha growth of Sclerotium sclerotiorum and influenced its extracellular cellulase and protease activities. Two putative small noncoding regulatory RNAs (sRNAs), referred to as csrB and csrC, were also revealed in the genome of LeC3. Double deletion of csrB and csrC in LeC3 led to increased resistance to NAL, RIF, Km, and NIT. However, no difference was observed between LeC3 and the csrB/csrC double mutant in their suppression of S. sclerotiorum hypha growth and production of extracellular enzymes.CONCLUSION:These results suggest that CsrA in LeC3 not only conferred its intrinsic MDR, but also contributed to its biocontrol activity.

The conserved Spt-Ada-Gcn5-Acetyltransferase (SAGA) complex controls eukaryotic transcription by modifying acetylation of histones. However, the mechanisms for this complex in regulating the transcription of target-specific genes remain largely unknown in phytopathogenic fungi.A filamentous fungal-specific transcription factor FgStuA was identified to interact with the SAGA complex physically. The coordinative mechanisms of FgStuA with the SAGA complex in regulating secondary metabolism and virulence were investigated in Fusarium graminearum with genetic, biochemical and molecular techniques.The transcription factor FgStuA binds to a 7-bp cis-element (BVTGCAK) of its target gene promoter. Under mycotoxin deoxynivalenol (DON) induction conditions, FgStuA recruits the SAGA complex into the promoter of TRI6, a core regulator of the DON biosynthesis gene cluster, leading to enhanced transcription of TRI6. During this process, we found that FgStuA is subject to acetylation by the SAGA complex, and acetylation of FgStuA plays a critical role for its enrichment in the TRI6 promoter. In addition, FgStuA together with the SAGA complex modulates fungal virulence.This study uncovers a novel regulatory mechanism of a transcription factor, which recruits and interacts with the SAGA complex to activate specific gene expression in pathogenic fungi.