Wheat crown rot is a destructive soil-borne disease affecting major wheat-growing regions worldwide. Mechanical transmission represents an important pathway for the spread of wheat diseases and combine harvesters, essential for large-scale farming operations, potentially facilitate long-distance pathogen dispersal through infected residue. However, the precise role of combine harvesters in the epidemiology of wheat crown rot remains unclear. The study revealed that the residue in the grain tank was significantly higher than that in other components, accounting for 44%-69% of the total residue. Pathogen isolation, identification, and PCR-based rapid detection confirmed the consistent presence of Fusarium pseudograminearum and F. graminearum in harvester residues following cross-regional operations from infected fields. Additionally, field trials demonstrated that after operating in disease-free fields, combine harvesters carrying pathogens led to disease incidence of 12% and 17% over two consecutive years. The application of physical and chemical treatments to harvesters prior to cross-regional operations significantly reduced field disease incidence. This study provides the first systematic evidence that combine harvesters serve as efficient vectors for long-distance dissemination of wheat crown rot pathogens, establishing a critical foundation for developing targeted biosecurity measures in wheat production systems.

Kiwifruit bacterial canker is a devastating disease caused by Pseudomonas syringae pv. actinidiae (Psa). NAC transcription factors play a significant role in host immunity. However, the potential molecular mechanism of resistance to semi-biotrophic Psa mediated by NAC transcription factors in kiwifruit remains unclear. In this study, we identified a typical NAC transcription factor, AcNAC10, which is involved in the jasmonic acid (JA) pathway and is highly expressed in resistant variety RH12 responsing to Psa. By overexpression and silencing of AcNAC10 in kiwifruit, it plays a positive role in enhancing kiwifruit resistance. Likewise, heterologous expression of AcNAC10 in transgenic Arabidopsis and tomato enhanced resistance to P. syringae. By directly binding to the promoter of AcLOX3, AcNAC10 inhibited its expression as a transcriptional suppressor. Using a yeast one-hybrid screening library, electrophoretic mobility shift assay (EMSA), and dual-luciferase reporter assays, it showed that AcTGA07 can activate the expression of AcNAC10. Moreover, we demonstrated that AcTGA07 decreased JA accumulation independently of the AcNAC10-AcLOX3 pathway. Our study elucidated the transcriptional cascade regulatory network of AcTGA07-AcNAC10-AcLOX3, which enhanced the disease resistance of kiwifruit to Psa by inhibiting JA synthesis.

BACKGROUND:Streptothricins (STs) are microbial-derived compounds effective against Pseudomonas syringae pv. actinidiae (Psa), the causal agent of kiwifruit bacterial canker. However, the risk of resistance development and underlying mechanisms in Psa remain unclear. This study aims to establish baseline sensitivity of Psa to STs, characterize resistance-associated phenotypes, and identify molecular resistance mechanisms to inform sustainable STs use in agriculture. RESULTS:Sensitivity testing of 186 Psa isolates from Chinese kiwifruit-producing regions revealed no naturally resistant strains, with a mean baseline half-maximal effective concentration (EC50) of 1.000 ± 0.240 μg mL-1 for STs. Laboratory-induced STs-resistant mutants (R-Psa) exhibited significant fitness costs, slower growth rates, impaired motility, and complete loss of virulence in planta, with no leaf necrosis observed in inoculated kiwifruit. Cross-resistance assays showed no or low cross-resistance to streptomycin, tetramycin, copper hydroxide, and kasugamycin. Molecular analyses identified a GNAT-family acetyltransferase, P-SatA, as the key resistance determinant: overexpression of P-SatA reduced STs sensitivity by 100-fold, while gene deletion restored wild-type sensitivity. In vitro validation confirmed P-SatA inactivates STs via acetylation, abolishing antibacterial activity. CONCLUSION:This study establishes that STs resistance in Psa is mediated by P-SatA-dependent acetylation, with resistant strains incurring substantial fitness penalties that limit their environmental competitiveness. The absence of natural resistance and low cross-resistance to other pesticides highlight STs as a sustainable option for kiwifruit canker management. These findings advance our understanding of metabolic resistance mechanisms in plant pathogens and provide a scientific basis for optimizing STs application to mitigate resistance risks. © 2025 Society of Chemical Industry.

Apple Valsa canker (AVC), primarily caused by the pathogenic fungus Valsa mali, is a devastating disease of apple. The development and application of high efficiency and low toxicity fungicides are of great significance for disease control. Natural active substances serve as a vital foundation for the development of novel green fungicides. In previous studies, the endophytic fungus Aa-Lcht was confirmed to contain specific inhibitory effect against V. mali. This study confirmed that Aa-Lcht fermentation broth (FB)'s suppression of V. mali growth and conidial germination, exhibiting AVC prevention. Through extraction, isolation, and purification, one active substance with high inhibitory effect on V. mali was obtained and identified as altenusin. Its concentration value for 50 % of maximal effect (EC50 values) against V. mali mycelium growth was 3.118 mu g/mL. Before V. mali infection, the lesion length of apple twigs and lesion area of fruits pretreated with altenusin decreased by 47.27 % and 80.52 %, respectively. Further research revealed that the hyphae of V. mali treated with altenusin exhibited irregular thickening of cell walls, severe vacuolation within the cells, and protoplasmic exudation. Meanwhile, transcriptome analysis indicated that altenusin primarily inhibited V. mali by interfering with the normal hyphal cell metabolism, substance degradation, peptidase activity, and proteolysis functions. Additionally, altenusin could also significantly up-regulate the expression of immunity resistance-related genes MdCYP81F2, MdPR2, MdPR4, and MdPR5 in apple. Summarizing the above, the altenusin provides valuable insights for the development of novel green fungicides for controlling AVC disease, contributing to the safe and healthy development of apple production.

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.

Pseudomonas syringae pv. actinidiae (Psa) is a significant pathogenic bacterium affecting the kiwifruit industry. This study investigated the target sites of streptothricin-F (ST-F), produced by Streptomyces lavendulae gCLA4. The inhibition of ST-F on Psa was examined by the microscopic structural differences of Psa before and after treatment with ST-F, as well as the interaction between ST-F and cell division-related proteins. The results revealed filamentation of Psa after ST-F treatment, and fluorescence microscopy showed that ST-F inhibited the formation of the Z-ring composed of FtsZ protein. In vitro experiments and molecular docking demonstrated that ST-F can bind to FtsZ with a binding energy of 0.4 μM and inhibit FtsZ's GTP-dependent polymerization reaction. In addition, ST-F does not exert inhibitory effects on cell division in Psa strains overexpressing ftsZ. In conclusion, FtsZ is one of the target sites for ST-F inhibition of Psa, highlighting its potential as a therapeutic target for controlling Psa-induced kiwifruit bacterial canker.

Pumpkin (Cucurbita moschata), which belongs to the gourd family (Cucurbitaceae), is widely planted throughout the world. In June 2023, many pumpkin plants (cv. Miben) displayed leaf blight and chlorosis in fields located in Suizhou (31.99°N, 113.02°E), Hubei Province, China. The disease incidence ranged from 30 to 40% in nine fields, 6.3 ha in total. The symptoms were irregularly shaped lesions that expanded along the mid-vein until the leaf turned brown and wilted. Fungal isolations were performed as described previously (Liu et al. 2023). Twenty pumpkin leaf samples with typical symptoms were collected and cut into 1 cm×1 cm pieces. The diseased tissue was surface-sterilized in 75% ethanol for 30 sec, plated on potato dextrose agar (PDA) medium and incubated at 25℃ for 3 days. Then, the emerging single fungal hyphal tip was transferred onto PDA plates to obtain purified isolates. A total of eighteen isolates on PDA plates were initially white and then developed to dark gray. The 5-day-old cultures growing on mung bean medium produced conidia that were black, single-celled, smooth, spherical or oblate, and ranged in size from 14.5 to 20.8 μm×13.3 to 20.5 μm (n=50). Therefore, the isolates were morphologically identified as Nigrospora sphaerica. Moreover, the genomic DNA of the isolates (HB-P1,HB-P2, and HB-P3) was extracted for amplification and sequencing of the regions of internal transcribed spacer (ITS) (White et al. 1990), nuclear large subunit rRNA (nLSU) (O'Donnell 1992; Rehner and Samuels 1994), and β-tubulin (TUB2) (Glass and Donaldson 1995), with primers ITS1/ITS4, LROR/LR3, and Bt2a/Bt2b, respectively. Sequences were submitted to GenBank under accession numbers PP348112, PP348113, PP348114 (ITS), PP411414, PP411415, PP411416 (nLSU), and PP357438, PP357439, PP357440 (TUB2). BLASTn showed that the sequences ITS, nLSU, and TUB2 of HB-P1, HB-P2, and HB-P3 had >99% nucleotide identities ((ITS: 100%, 508/508 bp, MF996488.1; 99.8%, 506/507, ON326588.1; 100%, 500/500 ,MK748317.1), (nLSU: 99.83%, 573/574, KT462720.1; 99.83% , 574/575 bp, KT462720.1; 99.65%, 575/577, KT462720.1), and (TUB2: 100%, 388/388, MN719407.1; 99.74%, 387/388, MN719407.1; 100%, 387/387, MN719407.1)) with Nigrospora sphaerica, respectively. A multilocus (ITS, nLSU and TUB2) phylogenetic analysis indicated that the isolates were Nigrospora sphaerica. Pathogenicity of three isolates were tested on pumpkin plants (cv. Miben). Fifteen pumpkin plants were inoculated by spraying the leaves (1×106 spores/ml), respectively, and 10 pumpkin plants were treated with sterile water as a negative control. All plants were incubated in an artificial climate box (LongYue, ShangHai) at 25℃ for 12 days. The experiment was repeated three times. Twelve days later, the inoculated pumpkin plants developed symptoms of leaf blight, while the control plants remained healthy. Then, pathogens were re-isolated from the each leaf of inoculated pumpkin plants and not from the control plants. Nigrospora sphaerica has been previously reported to cause leaf spot on watermelon in Malaysia (Ismail and Abd Razak 2021). To our knowledge, this is the first report of N. sphaerica causing leaf blight on pumpkin in China. This new disease can cause leaf blight, which may affect pumpkin productivity.

Tomato is consumed worldwide as fresh or processed food products. However, soilborne diseases of tomato plants caused by coinfection of various pathogens result in great economic losses to the tomato industry. It is difficult to accurately identify and diagnose soilborne diseases of tomato plants caused by pathogen complexes. In this study, we investigated field diseases of tomato plants by pathogen isolation and molecular identification and found that tomato wilt was caused by coinfection of Fusarium brachygibbosum, F. oxysporum, and Ralstonia solanacearum. Therefore, developing a method for simultaneous detection of DNA from F. brachygibbosum, F. oxysporum, and R. solanacearum is of great importance to efficiently and accurately monitor disease development at different growth stages of tomato plants. In this study, we performed a comparative genomic analysis of F. brachygibbosum, F. oxysporum, and R. solanacearum and determined the primer sets for simultaneous detection of DNA from these target pathogens. Then, we tested the reagent and condition parameters of multiplex PCR, including primers, dNTP and Mg2+ concentrations, and annealing temperatures, to determine the optimal parameters of a multiplex PCR system. We evaluated the specificity, sensitivity, and stability of the multiplex PCR system based on the optimized reaction conditions. The multiplex PCR system can specifically identify 13 target pathogens from 57 different fungal and bacterial pathogens, at the lower detection limit of the three target pathogens at concentrations of 100 pg/μl. In addition, we can accurately identify the three pathogens in tomato plants using the optimized multiplex PCR method. These results demonstrated that the multiplex PCR method developed in this study can simultaneously detect DNA from F. brachygibbosum, F. oxysporum, and R. solanacearum in a single PCR system to accurately identify and diagnose the pathogen causing tomato wilt.

Mould and mycotoxin contamination is an ongoing issue in agriculture and food industry. Production by Aspergillus niger DTZ-12 in Guizhou dried red chilies was found, leading to significant economic losses. In this study, the inhibitive efficacy (Effective Concentration, EC) of cinnamaldehyde (CIN), eugenol (EUG), carvacrol (CAR), and linalool (LIN) against A. niger DTZ-12 were evaluated. CIN with the best antifungal capacity was then investigated for the comprehensive inhibitory activity against A. niger DTZ-12 including mycelia, spores, and physiological activities. Results showed that CIN can effectively retard mycelial growth, spore germination, and OTA production of A. niger DTZ-12 in vitro and in dried red chilies during storage. At physiological level, CIN can increase cell membrane permeability by reducing the ergosterol, decrease ATP content and ATPase activity, and promote the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in cell. These results suggested that CIN displayed a great potential to be employed as a natural and effective alternative preservative during dried red chili storage.

A series of chalcone derivatives containing 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole was designed and synthesized. Structures of all compounds were characterized by 1H NMR, 13C NMR, 19F NMR, and HRMS. The biological activities of the compounds were determined with the mycelial growth rate method, and further studies showed that some compounds had good antifungal activities at the concentration of 100 μg/mL. The EC50 value of compound L31 was 15.9 μg/mL against Phomopsis sp., which were better than that of azoxystrobin (EC50 value was 69.4 μg/mL). In addition, the mechanism of action of compound L31 shown that compound can affect mycelial growth by disrupting membrane integrity against Phomopsis sp., and that the higher the concentration of the compound is, the greater the disruption of membrane integrity is.

Tomato (Solanum lycopersicum) is a common vegetable in the Solanaceae family, which as a nutritious vegetable, is widely planted in China. In July 2022, typical wilt symptoms were observed in tomato fields located in the regions of Shiyan (31.343781°N, 110.901005°E), Hubei. Surveys were performed on tomato plants showing symptoms of leaf chlorosis, dry wilt, and vascular wilts on stem and root. The disease incidence ranged from 40% to 70% in 12 surveyed fields, 11.2 ha in total.. After using a sterilized scalpel to cut a small piece of diseased tomato stem and root tissue, diseased tissue was surface disinfested in 75% ethanol for 30s, placed onto potato dextrose agar (PDA) medium,and incubated at 25℃ for 3 days. Then, the emerging single fungal hypha tip was cut and transferred into PDA plates to obtain single spore isolates. Sixteen fungi growing on PDA plates were initially white colonies with abundant aerial mycelium. After seven days of growth, the center of the plate was yellow to orange and red pigmentation was produced. The five-day-old cultures grown on mung bean medium produced macroconidia that were scarce and scattered, three to four septa, wide central cells, slightly sharp apexes, and ranged in size from 12.6-23.6 μm×2.8-4.1 μm (n=30). Microconidia were slightly curved, ovoid with zero to two septa, measuring 5.2-11.8 μm×1.8-2.7μm (n=30). Spherical chlamydospores were terminal or intercalary, and measured a diameter of 8.1-11.6 μm (n =30). Therefore, sixteen isolates were morphologically identified as Fusarium spp. Moreover, the genomic DNA of the isolates (HBSY-1,HBSY-2, and HBSY-3) was extracted for amplification and sequencing of the regions of internal transcribed spacer (ITS) (White et al., 1990), nuclear large subunit rRNA (nLSU) (O'Donnell, 1992; Vilgalys and Hester, 1990), and the translation elongation factor 1-alpha (EF1-α) (O'Donnell et al. 1998) with primers ITS1/ITS4, NL1/LR3, and EF1/2, respectively. Sequences were submitted to GenBank under accession numbers OP959509, OQ568650, OQ568651 (ITS), OQ186731, OQ568652, OQ568653 (nLSU), and OP957576, OQ572485, OQ572486 (EF1-α). BLASTn showed that the sequences ITS, nLSU, and EF1-α were matched 99.61% (508/510 bp; KU528864.1), 99.90% (993/994 bp; GQ505450.1), and 99.85% (651/652; ON032449.1) to Fusarium brachygibbosum, respectively. Multilocus phylogenetic analysis showed that the isolate was of the same clade as F. brachygibbosum. Therefore, morphological characterization and molecular data identified the fungus as F. brachygibbosum. Pathogenicity of the isolate (HBSY-1) was tested on ten seedlings of tomato (cv. Hezuo908). Tomatoes were inoculated by spraying with conidial suspensions (1×107 spores/mL) at the rootstock region of each plant. In addition, ten negative control plants were treated with sterile water. All plants were incubated in an artificial climate box (LongYue, ShangHai) at 25℃ for 12 days. The experiment was repeated three times. Twelve days later, inoculated tomatoes developed typical wilting symptoms of leaves and vascular wilts of stem and root, while the control plants remained healthy. Thus, pathogens were reisolated from the stems of inoculated plants and not from control plants. To our knowledge, this is the first report of F. brachygibbosum causing leaf wilt and vascular wilts of stem and root on tomatoes in China.

Pseudomonas syringae pv. actinidiae (Psa) is the causal agent of kiwifruit canker, a serious threat to commercial kiwifruit production worldwide. Studies of the movement path and the survival time of Psa in the host are crucial for integrated management programs. Hence, we used Psa with GFPuv gene (Psa-GFPuv) strain to investigate the movement path of Psa in leaves and branches, and the survival time of Psa in leaves under different environmental conditions. We found that the pathogen Psa spread longitudinally in the branches and leaves rather than transverse path. Additionally, the survival time of bacteria in fallen leaves under different environmental conditions were simulated by the way of Psa infecting the detached kiwifruit leaves. Psa survives the longest, up to 43 days in detached kiwifruit leaves with high humidity (above 80%) at 5 °C, and up to 32 days with low humidity (20%). At 15 °C, the Psa can survive in detached kiwifruit leaves for 20-30 days with increasing humidity. At 25 °C, it can only survive for 3 days with low humidity (20%) and 15 days with high humidity (above 80%). Furthermore, the population growth experiments showed that bacterial growth of Psa was more favorable in detached kiwifruit leaves with above 80% humidity at 5 °C. These results suggest that the survival condition of Psa in detached kiwifruit leaves is significantly affected by environmental conditions, and provide the basis for the control timing and technology of kiwifruit canker.

为了明确十堰市白粉虱[Trialeurodes vaporariorum(Westwood)]的取食偏好性、发生规律及不同药剂防治效果,对当地主要种植的5种作物上白粉虱发生情况进行田间调查,结合气象数据,明确当地白粉虱的取食偏好性及温度对其发生情况的影响,同时通过田间药剂试验,明确不同药剂(22.4%螺虫乙酯悬浮剂1500倍稀释液、6%乙基多杀菌素悬浮剂1000倍稀释液、50%吡蚜酮水分散粒剂1500倍稀释液、40%啶虫脒水分散粒剂7000倍稀释液)对当地白粉虱的防治效果,从而指导安全用药.结果表明,白粉虱在对黄瓜、辣椒、番茄、豇豆、普通白菜5种蔬菜的选择性上更趋向于取食黄瓜;结合气象数据可以看出,当温度高于25℃时,白粉虱种群数量快速增长;通过药剂试验可知,药后1d和3 d,40%啶虫脒水分散粒剂7000倍稀释液的防效最佳,分别为85.68%、75.45%;药后7d该药剂防效下降明显,50%吡蚜酮水分散粒剂1500倍稀释液的防效最佳,为33.93%;药后14 d,以上2种药剂的防效最佳,分别为16.70%、17.46%,试验所使用的4种药剂防效均随时间有所下降.

Diseases caused by two or more soil-borne pathogens are called compound soil-borne diseases. We have pioneered the "root splitter" and the imaging analysis system, providing a new tool for studying compound soil-borne diseases and a new method for evaluating crop resistance and pesticide (fertilizer) efficacy, and laying a foundation for the development of microbial agents, pesticides, and fertilizers. On this basis, we have developed a range of soil-borne disease disturbance agents “G15”, including a series of bio-organic fertilizers, liquid fertilizers and immune inducers. a) Microecological control series of bio-organic fertilizer: a new method of strain culture and classification screening based on the information of main components of organic fertilizer materials was used to obtain strains with high matching degree with organic materials. Then the process optimization technology was renewed by the ferulic acid rapid detection system. Through the 2-hour rapid detection and 30-day rapid optimization, the qualification rate of products is over 95%. It also standardized the basic operation methods and application doses for different crops and different application methods, and stabilized the application effect of products. The application of bioorganic fertilizers significantly reduced the abundance of pathogenic fungi and bacteria in the soil, and significantly inhibited the development of Solanaceae and Cucurbits wilt in the field (Figure 1A & 1B). b) Liquid fertilizer series products: liquid fertilizer with large, medium and trace elements, including nanometer silicon, ionic boron, ionic calcium, macroelement water-soluble fertilizer etc, which can improve crop quality and yield, increase disease resistance. We found that nano-silicon, ionic boron and ionic calcium can significantly promote the growth and disease resistance of grape (Figure 2). c) Salicylic Acid (SA), an immune inducer product, can improve the microbiological structure of soil by flushing with basic fertilizer; Foliar spraying can promote the expression of crop resistance genes, enhance the ability of drought resistance, salt resistance, oxidation resistance and heavy metal resistance, and improve the stress resistance and disease resistance of crops; Soaking or spraying can store the harvested fruits and keep them fresh; Combined with liquid fertilizer series products, crops can be put on the market early. However, SA is a natural product widely used in the plant kingdom and has a wide range of regulatory effects on plant resistance and growth. SA is slightly soluble in water and easily soluble in ethanol, ether and chloroform, so the concentration of SA solution is currently limited and the highest concentration can reach only 8%. Therefore, the concentration of SA and a higher proportion of ethanol in the solution limit the wide use of SA solution. In this study, we added willow bark to an aqueous solution containing PH 2.0-3.5 and soaked it at room temperature under the action of ultrasound and electrostatic field, which promoted the dissolution of water-soluble components and inhibited the dissolution of SA. After filtering the aqueous solution, polyethylene glycol was added to increase the solubility of SA, and finally the SA solution with a concentration of more than 12% was obtained. In order to verify the effect of the high content of SA on improving crop yield and ripening. We applied the leaf spray method to immature tomatoes in the field. The results showed that the total weight of 30 tomatoes in the treatment group was 7.4 kg, while in the control group it was 5.55 kg, an increase of 32.97%. The tomatoes in the treatment group were red in a wide range and reached the level of natural ripeness, while the tomatoes in the control group were cyan in a wide range and were not yet ripe. In addition, the average sugar content of tomatoes in the treatment group was 7.33, while it was 5.85 in the control group (Figure 3). The results suggest that spraying with a highly concentrated SA solution before flowering and harvesting can increase the yield and sweetness of tomatoes, adjust the uniform ripening time of tomatoes, effectively reduce tomato cultivation obstacles and harvesting costs, and improve the benefits of cultivation. Therefore, in order to prevent and control the compound soil-borne diseases caused by multiple soil-borne pathogens, we proposed a combination of bio-organic fertilizers, liquid fertilizers with large, medium and trace elements and immune inducers to regulate the composition of soil microbial community, improve the soil ecological environment and promote crop growth to comprehensively control the compound soil-borne diseases.

本文选取3个辣椒品种和1个番茄品种,调查十堰地区茄科蔬菜病虫害发生情况,以期摸清病虫害发生规律,为当地茄科蔬菜病虫害科学防治提供参考依据,保障蔬菜生产安全.结果表明:十堰地区辣椒发生真菌性病害5种、生理性病害1种、虫害1种;番茄发生真菌性病害2种;病害重于虫害.其中,重发病害为辣椒白绢病和番茄晚疫病,发病率分别高达89.09%、100.00%,病情指数分别为90.30、100.00.

BACKGROUND:Kiwifruit bacterial canker (KBC) caused by Pseudomonas syringae pv. actinidiae (Psa) is the main limiting factor in the kiwifruit industry. This study aimed to identify bacterial strains with antagonistic activity against Psa, analyze antagonistically active substances and provide a new basis for the biological control of KBC. RESULTS:A total of 142 microorganisms were isolated from the rhizosphere soil of asymptomatic kiwifruit. Among them, an antagonistic bacterial strain was identified as Paenibacillus polymyxa YLC1 by 16S rRNA sequencing. KBC control by strain YLC1 (85.4%) was comparable to copper hydroxide treatment (81.8%) under laboratory conditions and field testing. Active substances of strain YLC1 were identified by genetic sequence analysis using antiSMASH. Six biosynthetic active compound gene clusters were identified as encoding ester peptide synthesis, such as polymyxins. An active fraction was purified and identified as polymyxin B1 using chromatography, hydrogen nuclear magnetic resonance (NMR), and liquid chromatography-mass spectrometry. In addition, polymyxin B1 also was found significantly to suppress the expression of T3SS-related genes, but did not affect the growth of Psa at low concentrations. CONCLUSION:In this study, a biocontrol strain P. polymyxa YLC1 obtained from kiwifruit rhizosphere soil exhibited excellent control effects on KBC in vitro and in field tests. Its active compound was identified as polymyxin B1, which inhibits a variety of pathogenic bacteria. We conclude that P. polymyxa YLC1 is a biocontrol strain with excellent prospects for development and application. © 2023 Society of Chemical Industry.

为充分利用猕猴桃园资源,对猕猴桃溃疡病进行防控,增加果农收入,2021年,根据猕猴桃树栽培规律和方法,选择了油菜、黑豆、白菜、紫云英、苦荞以及蒲公英等6种作物进行林下套种对比试验.结果表明,选择的6个套作作物均能降低猕猴桃溃疡病的发病率,其中防控效果最好的是蒲公英,防效达64.56％.在次年对林下套种蒲公英进行进一步试验,结果表明,套种蒲公英可降低猕猴桃溃疡病的发病程度,病情指数防效为61.18％,病株率防效为48.57％.同时,蒲公英收获每年能为果农增加收入4 000元/667m2,提高了果园的资源利用率,实现了农民增收增产.

Tomato wilt is a widespread soilborne disease of tomato that has caused significant yield losses in many tomato growing regions of the world. Previously, it was reported that tomato wilt can be caused by many pathogens, such as Fusarium oxysporum, Ralstonia solanacearum, Ralstonia pseudosolanacearum, Fusarium acuminatum, and Plectosphaerella cucumerina. In addition, we have already reported that Fusarium brachygibbosum caused symptomatic disease of tomato wilt for the first time in China. The symptoms of tomato wilt caused by these pathogens are similar, making it difficult to distinguish them in the field. However, F. brachygibbosum specific identification method has not been reported. Therefore, it is of great importance to develop a rapid and reliable diagnostic method for Fusarium brachygibbosum to establish a more effective plan to control the disease. In this study, we designed F. brachygibbosum-specific forward primers and reverse primers with a fragment size of 283bp located in the gene encoding carbamoyl phosphate synthase arginine-specific large chain by whole genome sequence comparison analysis of the genomes of eight Fusarium spp.. We then tested different dNTP, Mg2+ concentrations, and annealing temperatures to determine the optimal parameters for the PCR system. We evaluated the specificity, sensitivity and stability of the PCR system based on the optimized reaction system and conditions. The PCR system can specifically identify the target pathogens from different fungal pathogens, and the lower detection limit of the target pathogens is at concentrations of 10 pg/uL. In addition, we can accurately identify F. brachygibbosum in tomato samples using the optimized PCR method. These results prove that the PCR method developed in this study can accurately identify and diagnose F. brachygibbosum.

Pseudomonas syringae pv. tomato DC3000 (PstDC3000) is an important plant pathogen that infects tomatoes and Arabidopsis. Thiamine and its derivative thiamine pyrophosphate (TPP) are cofactors that play an important role in the growth and survival of many bacterial microorganisms. However, the role of thiamine-related genes has not been determined in PstDC3000. Hence, to investigate the role of TPP in growth, resistance to stresses, and virulence of PstDC3000, double and quadruple mutants of thiamine biosynthesis-related genes (thiD/E, thiS/G, and thiD/E/S/G deletion mutants) as well as a single mutant of a lipoprotein-related gene (apbE) were constructed. Our results showed that growth of the thiD/E, thiS/G, and thiD/E/S/G mutants in the mannitol-glutamate (MG) medium was significantly lower than that of the wild type (WT) and their growth could be restored to the WT level with the addition of exogenous thiamine, whereas mutation of the apbE gene did not affect its growth in vitro. While tolerance to acid, osmotic, and oxidative stresses for the double mutants was similar to the WT, tolerance to stresses for the apbE mutant was reduced as compared to the WT. In addition, all four mutants exhibited reduced virulence and growth in tomatoes. However, when the double and quadruple mutants were inoculated with exogenous thiamine, the virulence and growth rate of these mutants were restored to the WT level. These results indicated that the thiD/E, thiS/G, and thiD/E/S/G mutants exhibiting growth deficiency in planta are probably due to a lack of thiamine biosynthesis, thus reducing colonization in tomatoes. On the other hand, it is possible that the apbE mutant exhibited reduced stress tolerances, thus resulting in reduced colonization. Overall, our findings suggest that the thiamine biosynthetic (TBS) pathway plays an important role in the colonization and infection of PstDC3000. Therefore, the thiamine biosynthetic pathway could be used as the target to develop new control measures for a bacterial spot in tomatoes.

Highly active and novel antifungal compounds are continuously researched from natural products for pesticide development. Picrasma quassioides (D. Don) Benn, a species of Simaroubaceae, is used in traditional Chinese medicine to treat colds and upper respiratory infections. In this study, the active ingredients of P. quassioides and their antifungal activities against plant pathogenic fungi are investigated to explore the practical application of the plant in the agricultural field. The results showed that the extracts of P. quassioides exhibited highly significant preventive and curative effects on apple valsa canker (AVC) with a reduction of lesion diameter were 80.28% and 83.63%, respectively, and can improve the resistance of apple trees to a pathogen. Five antifungal compounds, namely, canthin-6-one (T1), nigakinone (T2), 4,5-dimethoxycanthin-6-one (T3), 1-methoxycarbonyl-β-carboline (T4), and 1-methoxycarbonyl-3-methoxyl-β-carboline (T5), are isolated from P. quassioides using the bioassay-guided method. This is the first report of 1-methoxycarbonyl-3-methoxyl-β-carboline as a natural product. Canthin-6-one shows strong in vitro inhibitory activity against 11 species of plant pathogenic fungi, and their EC50 values range from 1.49 to 8.80 mg/L. The control efficacy of canthin-6-one at 2000 mg/L are 87.88% and 94.37% against AVC and 80.10% and 84.73% against apple anthracnose (C. gloeosporioides), respectively. Additionally, V. mali is observed after treatment with cannin-6-one, although microscopic. This is the first study on the control of the secondary metabolites of P. quassioides against plant fungal diseases. The results show that P. quassioides is a potential resource for the development of botanical fungicides.