The G143S mutation in cytochrome b confers high resistance to pyraclostrobin in Fusarium pseudograminearum.

BACKGROUND: Wheat crown rot (WCR), primarily caused by Fusarium pseudograminearum has become more and more prevalent in winter wheat areas in China. However, limited fungicides have been registered for the control of WCR in China so far. Pyraclostrobin is a representative quinone outside inhibitor (QoI) with excellent activity against Fusarium spp. There is currently limited research on the resistance risk and resistance mechanism of F. pseudograminearum to pyraclostrobin. RESULTS: Here, we determined the activity of pyraclostrobin against F. pseudograminearum. The EC50 values ranged from 0.022 to 0.172 µg mL-1 with an average EC50 value of 0.071 ± 0.030 µg mL-1. Four highly pyraclostrobin-resistant mutants were obtained from two sensitive strains by ultraviolet (UV) mutagenesis in the laboratory. The mutants showed decreased mycelial growth rate and virulence as compared with the corresponding wild-type strains, indicating that pyraclostrobin resistance suffered a fitness penalty in F. pseudograminearum. It was found that the high resistance of four mutants was caused by the G143S mutation in Cytb. Molecular docking analysis also further confirms that the G143S mutation in Cytb decreased the binding affinity between pyraclostrobin and Cytb. CONCLUSION: The resistance risk of F. pseudograminearum to pyraclostrobin could be low to medium. Although a mutation at the G143S position of Cytb could potentially occur, this mutation decreases the fitness of the mutant, which may reduce its survival in the environment. Therefore, the negative consequences of a possible mutation are lower. This makes pyraclostrobin a good candidate for controlling crown rot in wheat. © 2024 Society of Chemical Industry.

Functional Differentiation of the Succinate Dehydrogenase Subunit SdhC Governs the Sensitivity to SDHI Fungicides, ROS Homeostasis, and Pathogenicity in Fusarium asiaticum.

Succinate dehydrogenase (SDH) is an integral component of the tricarboxylic acid cycle (TCA) and respiratory electron transport chain (ETC), targeted by succinate dehydrogenase inhibitors (SDHIs). Fusarium asiaticum is a prominent phytopathogen causing Fusarium head blight (FHB) on wheat. Here, we characterized the functions of the FaSdhA, FaSdhB, FaSdhC1, FaSdhC2, and FaSdhD subunits. Deletion of FaSdhA, FaSdhB, or FaSdhD resulted in significant growth defects in F. asiaticum. The FaSdhC1 or FaSdhC2 deletion mutants exhibited substantial reductions in fungal growth, conidiation, virulence, and reactive oxygen species (ROS). The FaSdhC1 expression was significantly induced by pydiflumetofen (PYD). The ΔFaSdhC1 mutant displayed hypersensitivity to SDHIs, whereas the ΔFaSdhC2 mutant exhibited resistance against most SDHIs. The transmembrane domains of FaSdhC1 are essential for regulating mycelial growth, virulence, and sensitivity to SDHIs. These findings provided valuable insights into how the two SdhC paralogues regulated the functional integrity of SDH, ROS homeostasis, and the sensitivity to SDHIs in phytopathogenic fungi.

Risk assessment and molecular mechanism of Sclerotium rolfsii resistance to boscalid.

Boscalid, a widely used SDHI fungicide, has been employed in plant disease control for over two decades. However, there is currently no available information regarding its antifungal activity against Sclerotium rolfsii and the potential risk of resistance development in this pathogen. In this study, we evaluated the sensitivity of 100 S. rolfsii strains collected from five different regions in China during 2018-2019 to boscalid using mycelial growth inhibition method and assessed the risk of resistance development. The EC50 values for boscalid ranged from 0.2994 µg/mL to 1.0766 µg/mL against the tested strains, with an average EC50 value of 0.7052 ± 0.1473 µg/mL. Notably, a single peak sensitivity baseline was curved, indicating the absence of any detected resistant strains. Furtherly, 10 randomly selected strains of S. rolfsii were subjected to chemical taming to evaluate its resistance risk to boscalid, resulting in the successful generation of six stable and inheritable resistant mutants. These mutants exhibited significantly reduced mycelial growth, sclerotia production, and virulence compared to their respective parental strains. Cross-resistance tests revealed a correlation between boscalid and flutolanil, benzovindiflupyr, pydiflumetofen, fluindapyr, and thifluzamide; however, no cross-resistance was observed between boscalid and azoxystrobin. Thus, we conclude that the development risk of resistance in S. rolfsii to boscalid is low. Boscalid can be used as an alternative fungicide for controlling peanut sclerotium blight when combined with other fungicides that have different mechanisms of action. Finally, the target genes SDHB, SDHC, and SDHD in S. rolfsii were initially identified, cloned and sequenced to elucidate the mechanism of S. rolfsii resistance to boscalid. Two mutation genotypes were found in the mutants: SDHD-D111H and SDHD-H121Y. The mutants carrying SDHD-H121Y exhibited moderate resistance, while the mutants with SDHD-D111H showed low resistance. These findings contribute to our comprehensive understanding of molecular mechanisms underlying plant pathogens resistance to SDHI fungicides.

Resistance Risk and Molecular Mechanism of Tomato Wilt Pathogen Fusarium oxysporum f. sp. lycopersici to Pyraclostrobin.

Tomato wilt disease caused by Fusarium oxysporum f. sp. lycopersici (Fol) results in a decrease in tomato yield and quality. Pyraclostrobin, a typical quinone outside inhibitor (QoI), inhibits the cytochrome bc1 complex to block energy transfer. However, there is currently limited research on the effectiveness of pyraclostrobin against Fol. In this study, we determined the activity of pyraclostrobin against Fol and found the EC50 values for pyraclostrobin against 100 Fol strains (which have never been exposed to QoIs before). The average EC50 value is 0.3739 ± 0.2413 µg/mL, indicating a strong antifungal activity of pyraclostrobin against Fol, as shown by unimodal curves of the EC50 values. Furthermore, we generated five resistant mutants through chemical taming and identified four mutants with high-level resistance due to the Cytb-G143S mutation and one mutant with medium-level resistance due to the Cytb-G137R mutation. The molecular docking results indicate that the Cytb-G143S or Cytb-G137R mutations of Fol lead to a change in the binding mode of Cytb to pyraclostrobin, resulting in a decrease in affinity. The resistant mutants exhibit reduced fitness in terms of mycelial growth (25 and 30 °C), virulence, and sporulation. Moreover, the mutants carrying the Cytb-G143S mutation suffer a more severe fitness penalty compared to those carrying the Cytb-G137R mutation. There is a positive correlation observed among azoxystrobin, picoxystrobin, fluoxastrobin, and pyraclostrobin for resistant mutants; however, no cross-resistance was detected between pyraclostrobin and pydiflumetofen, prochloraz, or cyazofamid. Thus, we conclude that the potential risk of resistance development in Fol toward pyraclostrobin can be categorized as ranging from low to moderate.

In situ Mo-doped ZnIn2S4/Ni-Ni Hofmann-type coordination polymer composites for photocatalytic hydrogen evolution reaction.

Solar energy-assisted hydrogen production technology is an essential tool for exploring hydrogen energy. To date, semiconductors have been used as the primary photocatalyst to generate hydrogen via photocatalytic water splitting. However, the high photogenerated electron-hole recombination rate of semiconductor photocatalysts results in a low hydrogen production rate. Herein, the synergistic effect of Mo-ion doping and the incorporation of Ni-based Hofmann-type coordination polymer (Ni-Ni HCP) on the photocatalytic performance of ZnIn2S4 (ZIS) is investigated. The hydrogen production rate of the prepared in-situ Mo doped ZnIn2S4 wrapped Ni-Ni HCP (Ni-Ni HCP/Mo-ZIS) sample under visible-light irradiation is 26.7 mmol g-1h-1, which is 10 times that of pure ZIS. Hydrogen production rate test, microscopic characterization, and density functional theory calculation confirm that the proposed dual modulation approach (combined ion doping and heterogeneous structure construction) could effectively increase the photocatalytic efficiency of ZIS. The stability of prepared samples is also examined by four-cycle photocatalytic hydrogen production tests. The proposed integrated method opens a new route for advancing renewable energy technology towards a sustainable future.

The intrinsic resistance of Fusarium solani to the Fusarium-specific fungicide phenamacril is attributed to the natural variation of both T218S and K376M in myosin5.

Fusarium solani is responsible for causing root rot in various crops, resulting in wilting and eventual demise. Phenamacril, a specific inhibitor of myosin5 protein, has gained recognition as an effective fungicide against a broad spectrum of Fusarium species. It has been officially registered for controlling Fusarium diseases through spray application, root irrigation, and seed dipping. In this study, phenamacril was observed to exhibit negligible inhibitory effects on F. solani causing crop root rot, despite the absence of prior exposure to phenamacril. Considering the high selectivity of phenamacril, this phenomenon was attributed to intrinsic resistance and further investigated for its underlying mechanism. Sequence alignment analysis of myosin5 proteins across different Fusarium species revealed significant differences at positions 218 and 376. Subsequent homology modeling and molecular docking results indicated that substitutions T218S, K376M, and T218S&K376M impaired the binding affinity between phenamacril and myosin5 in F. solani. Mutants carrying these substitutions were generated via site-directed mutagenesis. A phenamacril-sensitivity test showed that the EC50 values of mutants carrying T218S, K376M, and T218S&K376M were reduced by at least 6.13-fold, 9.66-fold, and 761.90-fold respectively compared to the wild-type strain. Fitness testing indicated that mutants carrying K376M or T218S&K376M had reduced sporulation compared to the wild-type strain. Additionally, mutants carrying T218S exhibited an enhanced virulence compared to the wild-type strain. However, there were no significant differences observed in mycelial growth rates between the mutants and the wild-type strain. Thus, the intrinsic differences observed at positions 218 and 376 in myosin5 between F. solani and other Fusarium species are specifically associated with phenamacril resistance. The identification of these resistance-associated positions in myosin5 of F. solani has significantly contributed to the understanding of phenamacril resistance mechanisms, thereby discouraging the use of phenamacril for controlling F. solani.

Occurrence and Chemical Control Strategy of Wheat Brown Foot Rot Caused by Microdochium majus.

Wheat brown foot rot (WBFR), caused by a variety of phytopathogenic fungi, is an important soilborne and seedborne disease of wheat. WBFR causes wheat lodging and seedling dieback, which seriously affect the yield and quality of wheat. In this study, 64 isolates of WBFR were isolated from different wheat fields in Yancheng city, Jiangsu Province, China. The internal transcribed spacer, elongation factor 1α, and RNA polymerase II subunit were amplified and the sequencing results of the fragments were analyzed with BLAST in NCBI. Through morphological and molecular identification, all of the isolates were identified as Microdochium majus. Verification by Koch's postulates confirmed that M. majus was the pathogen causing WBFR. The antifungal activities of fludioxonil and prochloraz against 64 isolates of M. majus were determined based on mycelial growth inhibition method. The results showed that fludioxonil and prochloraz had good antifungal activity against M. majus. The mean 50% effective concentration values of fludioxonil and prochloraz against M. majus were 0.2956 ± 0.1285 µg/ml and 0.0422 ± 0.0157 µg/ml, respectively. Control efficacy for seed-coating treatments conducted in a greenhouse indicated that M. majus severely damaged the normal growth of wheat, while seed coating with fludioxonil or prochloraz significantly reduced the disease incidence and improved the seedling survival rates. At fludioxonil doses of 7.5 g per 100 kg and prochloraz doses of 15 g per 100 kg, the incidence was reduced by 22.26 and 25.33%, seedling survival rates increased by 25.37 and 22.66%, and control efficacy reached 70.02 and 72.30%, respectively. These findings provide vital information for the accurate diagnosis and effective management of WBFR.

Bioactivity-Guided Subtraction of MIQOX for Easily Available Isoquinoline Hydrazides as Novel Antifungal Candidates.

The discovery of novel and easily available leads provides a convincing solution to agrochemical innovation. A bioassay-guided scaffold subtraction of the previous "Chem-Bio Model" isoquinoline-3-oxazoline MIQOX was conducted for identifying the easily available isoquinoline-3-hydrazide as a novel antifungal scaffold. The special and practical potential of this model was demonstrated by a phenotypic antifungal bioassay, molecular docking, and cross-resistance evaluation. A panel of antifungal leads (LW2, LW3, and LW11) was acquired, showing much better antifungal performance than the positive controls. Specifically, compound LW3 exhibited a broad antifungal spectrum holding EC50 values as low as 0.54, 0.09, 1.52, and 2.65 mg/L against B. cinerea, R. solani, S. sclerotiorum , and F. graminearum, respectively. It demonstrated a curative efficacy better than that of boscalid in controlling the plant disease caused by B. cinerea. The candidate LW3 did not show cross-resistance to the extensively used succinate dehydrogenase inhibitor (SDHI) fungicides and can efficiently inhibit resistant B. cinerea strains. The molecular docking of compound LW3 is quite different from that of the positive controls boscalid and fluopyram. This progress highlights the practicality of isoquinoline hydrazide as a novel model in fungicide innovation.

Evolution of Benzimidazole Resistance Caused by Multiple Double Mutations of ß-Tubulin in Corynespora cassiicola.

Cucumber target leaf spot caused by Corynespora cassiicola has devastated greenhouse cucumber production. In our previous study, the resistance monitoring of C. cassiicola to carbendazim was carried out, and a large number of resistant populations carrying various mutations (M163I&E198A, F167Y&E198A, F200S&E198A, or E198A) in ß-tubulin were detected. However, the single-point mutations M163I, F167Y, and F200S have remained undetected. To investigate the evolutionary mechanism of double mutations in ß-tubulin of C. cassiicola resistance to benzimidazoles, site-directed mutagenesis was used to construct alleles with corresponding mutation genotypes in ß-tubulin. Through PEG-mediated protoplast transformation, all the mutants except for the M163I mutation were obtained and conferred resistance to benzimidazoles. It was found that the mutants conferring the E198A or double-point mutations showed high resistance to carbendazim and benomyl, but the mutants conferring the F167Y or F200S mutations showed moderate resistance. Except, the F200S mutants showed low resistance, the resistance level of the other mutants to thiabendazole seemed no difference. In addition, compared to the other mutants, the F167Y and F200S mutants suffered a more severe fitness penalty in mycelial growth, sporulation, and virulence. Thus, combined with the resistance level, fitness, and molecular docking results, we concluded that the field double mutations (F167Y&E198A and F200S&E198A) evolved from the single mutations F167Y and F200S, respectively.

The G143A/S substitution of mitochondrially encoded cytochrome b (Cytb) in Magnaporthe oryzae confers resistance to quinone outside inhibitors.

BACKGROUND: Rice blast, caused by Magnaporthe oryzae, is a destructive disease threatening the production of staple foods worldwide. Quinone outside inhibitors (QoIs) are a group of chemicals exhibiting excellent activity against a majority of plant pathogens, with the disadvantage that pathogens can easily develop resistance to QoIs. RESULTS: Here, we investigated the activity of picoxystrobin against M. oryzae, which showed a great inhibitory effect on 100 strains of M. oryzae with half-maximal effective concentrations (EC50 ) ranging from 0.0251 to 0.1337 µg ml-1 . The EC50 values showed a continuous unimodal distribution that was identical to the normal distribution, suggesting the potency of our study to represent baseline sensitivity. In addition, nine resistant mutants were obtained by exposing M. oryzae to a high dosage of picoxystrobin in the laboratory; all of them showed cross-resistance to the other five QoI fungicides. Although some mutants showed a decreased resistance factor after ten successive cultures on fungicide-free medium, the resistance to picoxystrobin was still inheritable. Amino acid substitution of G143S was detected in eight of nine picoxystrobin-resistant mutants, and G143A was detected in only one of nine mutants. A fitness penalty was found in the mutants carrying G143S rather than G143A. CONCLUSION: Our findings suggested that M. oryzae had a mid to high risk of resistance to picoxystrobin. Considering this, we should be vigilant to the resistance risk and apply picoxystrobin sensibly in the field. © 2022 Society of Chemical Industry.

Cytochrome bc1 Complex: Potential Breach to Improve the Activity of Phenazines on Xanthomonas.

The effects of the natural pesticides, phenazines, were reported to be limited by some tolerant metabolism processes within Xanthomonas. Our previous studies suggested that the functional cytochrome bc1 complex, the indispensable component of the respiration chain, might participate in tolerating phenazines in Xanthomonas. In this study, the cytochrome bc1 mutants of Xanthomonas campestris pv. campestris (Xcc) and Xanthomonas oryzae pv. oryzae (Xoo), which exhibit different tolerance abilities to phenazines, were constructed, and the cytochrome bc1 complex was proven to partake a critical and conserved role in tolerating phenazines in Xanthomonas. In addition, results of the cytochrome c mutants suggested the different functions of the various cytochrome c proteins in Xanthomonas and that the electron channeled by the cytochrome bc1 complex to cytochrome C4 is the key to reveal the tolerance mechanism. In conclusion, the study of the cytochrome bc1 complex provides a potential strategy to improve the activity of phenazines against Xanthomonas.

Molecular Mechanism of Sclerotinia sclerotiorum Resistance to Succinate Dehydrogenase Inhibitor Fungicides.

Succinate dehydrogenase inhibitor (SDHI) fungicides have a wide spectrum of fungicidal effects on a variety of fungi causing plant diseases, including Sclerotinia stem rot caused by Sclerotinia sclerotiorum. However, the consistent use of site-specific SDHI fungicides can result in the development of resistant isolates with mutations in the SDHB, SDHC, or SDHD subunit thereby leading to a rapid decline of fungicide performance. In this study, we found that SDHC was genetically evolved into two isotypes SDHC1 and SDHC2 in S. sclerotiorum but not involved in the sensitivity to SDHI fungicides. In addition, we demonstrated that the A11V substitution in SDHB was not involved in the resistance of S. sclerotiorum to boscalid, and this substitution widely emerged in the field populations. Meanwhile, the P226L substitution in SDHB was demonstrated to confer boscalid resistance in S. sclerotiorum. The result of cross-resistance showed that the SDHB-P226L substitution exhibited a positive cross-resistance between boscalid and carboxin, fluopyram, pydiflumetofen, flubeneteram, pyraziflumid, fluindapyr, or penthiopyrad. Taken together, our results indicated that the P226L substitution in SDHB resulted in the resistance of S. sclerotiorum to SDHI fungicides but suffered from fitness penalty, especially the homozygous mutants conferring the P226L substitution in SDHB.

Risk assessment and molecular mechanism of Fusarium incarnatum resistance to phenamacril.

BACKGROUND: Cucumber fruit rot (CFR) caused by Fusarium incarnatum is a devastating fungal disease in cucumber. In recent years, CFR has occurred frequently, resulting in serious yield and quality losses in China. Phenamacril exhibits a specific antifungal activity against Fusarium species. However, no data for phenamacril against F. incarnatum is available. RESULTS: The sensitivity of 80 F. incarnatum strains to phenamacril was determined. The half maximal effective concentration (EC50 ) values ranged from 0.1134 to 0.3261 µg mL-1 with a mean EC50 value of 0.2170 ± 0.0496 µg mL-1 . A total of seven resistant mutants were obtained from 450 mycelial plugs by phenamacril-taming on potato dextrose agar (PDA) plates with 10 µg mL-1 of phenamacril, and the resistant frequency was 1.56%. Phenamacril-resistant mutants showed decreased mycelial growth, conidiation and virulence as compared with the corresponding wild-type strains, indicating that phenamacril resistance suffered a fitness penalty in F. incarnatum. In addition, using sequence analysis, the point mutations of S217P or I424S were discovered in Fimyosin-5 (the target of phenamacril). The site-directed mutagenesis of the S217P, P217S, I424S and S424I substitutions were constructed to reveal the relationship between the point mutations and phenamacril resistance. The results strongly demonstrated that the mutations of S217P and I424S in Fimyosin-5 conferred phenamacril-resistance in F. incarnatum. CONCLUSION: Phenamacril-resistant mutants were easily induced and their resistance level was high. The S217P or I424S substitutions in Fimyosin-5 conferring phenamacril resistance were detected and futherly verified by transformation assay with site-directed mutagenesis. Thus, we proposed that the resistance development of F. incarnatum to phenamacril is high risk. © 2022 Society of Chemical Industry.

Mechanism of Fusarium graminearum Resistance to Ergosterol Biosynthesis Inhibitors: G443S Substitution of the Drug Target FgCYP51A.

Fusarium head blight (FHB), caused by the Fusarium graminearum species complex, is a devastating fungal disease resulting in substantial yield and quality losses. Ergosterol biosynthesis inhibitors (EBIs) are the most popular chemicals for controlling FHB. Recently, the resistance of F. graminearum to EBIs has emerged in the field, and an amino acid substitution (G443S) of the sterol 14α-demethylase FgCYP51A was detected in the field resistant strains. To further illustrate the resistance mechanism of F. graminearum to EBIs, site-directed mutants conferring the G443S substitution of FgCYP51A were generated from the progenitor strain PH-1 via genetic transformation with site-directed mutagenesis. We found that the FgCYP51A-G443S substitution significantly decreased the sensitivity of F. graminearum to EBIs with EC50 values ranging from 0.1190 to 0.2302 µg mL-1 and EC90 values ranging from 1.3420 to 9.1119 µg mL-1 for tebuconazole. Furthermore, the FgCYP51A-G443S substitution decreased sexual reproduction and virulence, which will reduce the initial infection source of pathogen populations in the field, while the increase of sporulation capability may enhance the frequencies of the disease cycle, thereby contributing to epidemics of FHB disease. Surprisingly, the FgCYP51A-G443S substitution accelerated DON biosynthesis by upregulating TRI5 expression and enhancing the fluorescence intensity of TRI1-GFP, the marker protein of Fusarium toxisomes. Thus, we concluded that the FgCYP51A-G443S substitution regulates EBI-fungicide resistance and DON biosynthesis, increasing the risk of fungicide resistance development in the field, thereby threatening the control efficacy of EBIs against FHB.

Validamycin A Enhances the Interaction Between Neutral Trehalase and 14-3-3 Protein Bmh1 in Fusarium graminearum.

In agriculture, Trehalase is considered the main target of the biological fungicide validamycin A, and the toxicology mechanism of validamycin A is unknown. 14-3-3 proteins, highly conserved proteins, participate in diverse cellular processes, including enzyme activation, protein localization, and acting as a molecular chaperone. In Saccharomyces cerevisiae, the 14-3-3 protein Bmh1could interact with Nth1 to respond to specific external stimuli. Here, we characterized FgNth, FgBmh1, and FgBmh2 in Fusarium graminearum. ΔFgNth, ΔFgBmh1, and ΔFgBmh2 displayed great growth defects and their peripheral tips hyphae generated more branches when compared with wild-type (WT) PH-1. When exposed to validamycin A as well as high osmotic and high temperature stresses, ΔFgNth, ΔFgBmh1, and ΔFgBmh2 showed more tolerance than WT. Both ΔFgNth and ΔFgBmh1 displayed reduced deoxynivalenol production but opposite for ΔFgBmh2, and all three deletion mutants showed reduced virulence on wheat coleoptiles. In addition, coimmunoprecipitation (Co-IP) experiments suggested that FgBmh1 and FgBmh2 both interact with FgNth, but no interaction was detected between FgBmh1 and FgBmh2 in our experiments. Further, validamycin A enhances the interaction between FgBmh1 and FgNth in a positive correlation under concentrations of 1 to 100 µg/ml. In addition, both high osmotic and high temperature stresses promote the interaction between FgBmh1 and FgNth. Co-IP assay also showed that neither FgBmh1 nor FgBmh2 could interact with FgPbs2, a MAPKK kinase in the high-osmolarity glycerol pathway. However, FgBmh2 but not FgBmh1 binds to the heat shock protein FgHsp70 in F. graminearum. Taken together, our results demonstrate that FgNth and FgBmh proteins are involved in growth and responses to external stresses and virulence; and validamycin enhanced the interaction between FgNth and FgBmh1in F. graminearum.

Effects of left atrial appendage surgical treatment on the incidence of ischemic cerebrovascular accidents in patients with atrial fibrillation undergoing cardiac surgery.

BACKGROUND: We sought to assess different surgical methods for left atrial appendage treatment to determine whether any could reduce the incidence of atrial fibrillation-related long-term ischemic cerebrovascular accidents. METHODS: A total of 1243 patients were treated with left atrial appendage removal, and 107 patients (8.6%) were lost to follow-up and excluded. The primary outcome was the long-term incidence of ischemic cerebrovascular events (ie, ischemic stroke, excluding transient ischemic attack) and all-cause mortality. RESULTS: Of the 1136 patients, 37 (3.3%) had ischemic cerebrovascular events. The 1-year, 5-year, and 10-year freedoms from long-term ischemic cerebrovascular events of the left atrial appendage extracardiac ligation group were 99.7%, 94.0%, and 90.8%, respectively. The 1-year, 5-year, and 10-year survivals of the left atrial appendage intracardiac suture group were 99.7%, 94.6%, and 93.6%, respectively. There was a significant difference between the left atrial appendage extracardiac ligation group and the left atrial appendage excision group (P = .041). Seventeen patients (4.6%) had long-term ischemic cerebrovascular events in the left atrial appendage extracardiac ligation group (1.1% per year), 14 patients (3.5%) in the left atrial appendage intracardiac suture group (0.9% per year), and 6 patients (1.7%) in the left atrial appendage excision group (0.44% per year). Left atrial appendage excision can reduce the occurrence of long-term thrombotic stroke compared with left atrial appendage extracardiac ligation (95% confidence interval, 1.09-9.26; P = .035). CONCLUSIONS: For patients with atrial fibrillation, the removal of the left atrial appendage can effectively prevent stroke caused by atrial fibrillation.

Two-Stage Arterial Switch for Transposition of the Great Vessels in Older Children.

BACKGROUND: This study investigated a 2-stage arterial switch operation (ASO) to treat transposition of the great arteries (TGA) with intact ventricular septum (TGA-IVS) in late referral patients. METHODS: We retrospectively analyzed patients with TGA-IVS or TGA with restricted ventricular septal defects who had undergone 2-stage ASO at our institution from February 2007 to August 2018. Included were 41 patients: 21 (51.2%) who had undergone long-term 2-stage ASO and 20 (48.8%) who had undergone rapid 2-stage ASO. RESULTS: The long-term 2-stage group was older at ASO (3.5 vs 25 months; P < .001). Results were more satisfactory in the long-term group than in the rapid group for intensive care unit time (P = .004), mechanical ventilation time (P = .004), and length of stay (P = .007). No in-hospital death occurred in the long-term group, and the postoperative course was more manageable in the long-term group than in the rapid group. However, the risk of significant neoaortic regurgitation was lower in the rapid group, which also had a better left ventricular ejection fraction. CONCLUSIONS: The long-term group achieved better early-term outcomes than the rapid group. However, a high risk of neoaortic regurgitation and myocardial dysfunction was also noted.

Functional Roles of α1-, α2-, ß1-, and ß2-Tubulins in Vegetative Growth, Microtubule Assembly, and Sexual Reproduction of Fusarium graminearum.

The plant pathogen Fusarium graminearum contains two α-tubulin isotypes (α1 and α2) and two ß-tubulin isotypes (ß1 and ß2). The functional roles of these tubulins in microtubule assembly are not clear. Previous studies reported that α1- and ß2-tubulin deletion mutants showed severe growth defects and hypersensitivity to carbendazim, which have not been well explained. Here, we investigated the interaction between α- and ß-tubulin of F. graminearum. Colocalization experiments demonstrated that ß1- and ß2-tubulin are colocalized. Coimmunoprecipitation experiments suggested that ß1-tubulin binds to both α1- and α2-tubulin and that ß2-tubulin can also bind to α1- or α2-tubulin. Interestingly, deletion of α1-tubulin increased the interaction between ß2-tubulin and α2-tubulin. Microtubule observation assays showed that deletion of α1-tubulin completely disrupted ß1-tubulin-containing microtubules and significantly decreased ß2-tubulin-containing microtubules. Deletion of α2-, ß1-, or ß2-tubulin had no obvious effect on the microtubule cytoskeleton. However, microtubules in α1- and ß2-tubulin deletion mutants were easily depolymerized in the presence of carbendazim. The sexual reproduction assay indicates that α1- and ß1-tubulin deletion mutants could not produce asci and ascospores. These results implied that α1-tubulin may be essential for the microtubule cytoskeleton. However, our Δα1-2×α2 mutant (α1-tubulin deletion mutant containing two copies of α2-tubulin) exhibited normal microtubule network, growth, and sexual reproduction. Interestingly, the Δα1-2×α2 mutant was still hypersensitive to carbendazim. In addition, both ß1-tubulin and ß2-tubulin were found to bind the mitochondrial outer membrane voltage-dependent anion channel (VDAC), indicating that they could regulate the function of VDAC. IMPORTANCE In this study, we found that F. graminearum contains four different α-/ß-tubulin heterodimers (α1-/ß1-, α1-/ß2-, α2-/ß1-, and α2-/ß2-tubulin heterodimers), and they assemble together into a single microtubule. Moreover, α1- and α2-tubulins are functionally interchangeable in microtubule assembly, vegetative growth, and sexual reproduction. These results provide more insights into the functional roles of different tubulins of F. graminearum, which could be helpful for purification of tubulin heterodimers and development of new tubulin-binding agents.

Functional dissection of individual domains in group III histidine kinase Sshk1p from the phytopathogenic fungus Sclerotinia sclerotiorum.

A conserved kinase domain and phosphoryl group receiver domain at the C-terminus and poly-HAMP domains at the N-terminus comprise the structural components of the group III HK which was considered as a potential antifungal target. However, the roles of individual domains in the function of group III HKs have rarely been dissected in fungi. In this study, we dissected the roles of individual domains to better understand the function of Sshk1p, a group III HK from Sclerotinia sclerotiorum. The results suggest that individual domains play different roles in the functionality of Sshk1p and are implicated in the regulation of mycelial growth, sclerotia formation, pathogenicity. And the mutants of each domain in Sshk1 showed significantly increased sensitivity to hyperosmotic stress. However, the mutants of each domain in Sshk1 showed high resistance to fludioxonil and dimethachlon which suggested that all nine domains of Sshk1p were indispensable for susceptibility to fludioxonil and dimethachlon. Moreover, deletion of each individual domain in Sshk1 cancelled intracellular glycerol accumulation and increased SsHog1p phosphorylation level triggered by NaCl and fludioxonil, suggesting that all the domains of Sshk1 were essential for Sshk1-mediated SsHog1p phosphorylation and subsequent polyol accumulation in response to fludioxonil and hyperosmotic stress.

Antifungal Activity of Quinofumelin against Fusarium graminearum and Its Inhibitory Effect on DON Biosynthesis.

Fusarium graminearum, causal agent of Fusarium head blight (FHB), causes a huge economic loss. No information is available on the activity of quinofumelin, a novel quinoline fungicide, against F. graminearum or other phytopathogens. In this study, we used mycelial growth and spore germination inhibition methods to determine the inhibitory effect of quinofumelin against F. graminearum in vitro. The results indicated that quinofumelin excellently inhibited mycelial growth and spore germination of F. graminearum, with the average EC50 values of 0.019 ± 0.007 µg/mL and 0.087 ± 0.024 µg/mL, respectively. In addition, we found that quinofumelin could significantly decrease deoxynivalenol (DON) production and inhibit the expression of DON-related gene TRI5 in F. graminearum. Furthermore, we found that quinofumelin could disrupt the formation of Fusarium toxisome, a structure for producing DON. Western blot analysis demonstrated that the translation level of TRI1, a marker gene for Fusarium toxisome, was suppressed by quinofumelin. The protective and curative assays indicated that quinofumelin had an excellent control efficiency against F. graminearum on wheat coleoptiles. Taken together, quinofumelin exhibits not only an excellent antifungal activity on mycelial growth and spore germination, but also could inhibit DON biosynthesis in F. graminearum. The findings provide a novel candidate for controlling FHB caused by F. graminearum.