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The placement of Corynespora olivacea within the large genus Corynespora (Pleosporales) is controversial, because the species is distantly related to other congeners, including the type species C. cassiicola. Corynespora cassiicola is a polyphagous, cosmopolitan plant pathogen. Successful colonization of plant tissues requires the pathogen's effector repertoire to modulate host cell physiology and facilitate the infection process. We sequenced and performed functional annotations on the genomes of C. cassiicola CC_29 (genome size about 44.8 Mb; isolated from soybean leaves) and C. olivacea CBS 114450 (32.3 Mb). Our phylogenomic approach showed that C. cassiicola is distantly related to C. olivacea, which clustered among the Massarinaceae family members, supporting a hypothesis that C. olivacea was originally misclassified. The predicted sizes for the proteome and secretome of C. cassiicola (18,487 and 1327, respectively) were larger than those of C. olivacea (13,501 and 920; respectively). Corynespora cassiicola had a richer repertoire of effector proteins (CAZymes, proteases, lipases, and effectors) and genes associated with secondary metabolism than did C. olivacea. [ABSTRACT FROM AUTHOR]

Target leaf spot (TLS), caused by Corynespora cassiicola , is an emerging and high-incidence disease that has spread rapidly on the global scale. Aerospores released by infected plants play a significant role in the epidemiology of cucumber TLS disease; however, no data exist concerning the infectiousness and particle size of C. cassiicola aerospores, and the experimental evidence for the aerospores transmission was lacking. In the present study, highly effective approaches to collect and quantify aerospores were developed for exposure chamber and greenhouse studies. Quantifiable levels of C. cassiicola aerospores were detected in 27 air samples from nine naturally infested greenhouses, ranging from 198 to 5,969 spores/m3. The C. cassiicola strains isolated from air samples were infective to healthy cucumber plants. Exposure chambers were constructed to study the characteristics of C. cassiicola aerospores released by artificially infested cucumber plants. The particle size of C. cassiicola ranged predominately from 2.1 to 4.7 μm, accounting for 71.97% of the total amount. In addition, the transmission dynamics of C. cassiicola aerospores from donor cucumber plants to recipient cucumber plants were confirmed in exposure chambers and greenhouses. The concentration of C. cassiicola aerospores was positively associated with cucumber TLS disease severity. This study suggested that aerospore dispersal is an important route for the epidemiology of plant fungal disease, and these data will contribute to the development of new strategies for the effective alleviation and control of plant diseases. [ABSTRACT FROM AUTHOR]

The pathogenic fungi, Rigidoporus microporus and Corynespora cassiicola are among the major agents of root and leaf disease of rubber tree (Hevea brasiliensis). In this study, endophytic fungi were isolated from seeds of H. brasiliensis obtained from different regions of Malaysia to determine the diversity of endophytes inhabiting the seeds and to select a potential biocontrol agent against selected Hevea pathogens. Through morphological observation and molecular identification, six genera were identified namely Aspergillus, Colletotrichum, Diaporthe, Lasiodiplodia, Mucor and Pseudofusicoccum. Isolate PN3 which showed 99.82% identity to Aspergillus terreus was selected as a candidate to evaluate its biocontrol potential against R. microporus and C. cassiicola as it displayed promising inhibitory potential in preliminary experiments. A. terreus showed inhibition of 81.24%, 70.35% and 64.19% against R. microporus and two races of C. cassiicola namely CLN 16 and CSB 16 respectively in dual culture assay. In dipped stick inhibition assay, A. terreus showed 100% inhibition to the growth of R. microporus. A. terreus also reduced infection of leaves cultured with C. cassiicola CLN 16 and CSB 16 by 93.33% and 86.67% respectively. This study has identified some of the fungal species inhabiting the seeds of H. brasiliensis which may have potential as biocontrol agents. [ABSTRACT FROM AUTHOR]

BACKGROUND For Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei, a necrotrophic pathogen with a broad host range and a worldwide distribution, resistance to fluopyram has been attributed to mutations in SdhB/C/D subunit of the succinate dehydrogenase (SDH) complex. In our previous study, two point mutations in SdhB from isoleucine to valine at position 280 (I280V) and histidine to tyrosine at position 278 (H278Y) showed different resistance phenotypes to fluopyram and boscalid. This research was conducted to explore the correlation between the mutation of SdhB‐I280V or SdhB‐H278Y and resistance to fluopyram or boscalid and its effect on the fitness characteristics of C. cassiicola. RESULTS: The sdhB gene in a succinate dehydrogenase inhibitor (SDHI)‐sensitive C. cassiicola strain (wild type) was successfully replaced with the mutant sdhB gene (GTT at position 280, SdhB‐I280V) or with the mutant sdhB gene (TAC at position 278, SdhB‐H278Y,). Compared with the wild‐type strain, the replacement mutants exhibited significantly different resistance phenotypes, with SdhB‐V280 demonstrating moderate resistance to fluopyram and low resistance to boscalid, while SdhB‐Y278 was supersensitive to fluopyram and very highly resistant to boscalid. Both of the mutants exhibited decreased sensitivity to salt stress and increased SDH activity. These two mutations had no effect on the mycelial growth rate, sporulation ability, pathogenicity in vivo, sensitivity to osmotic stress and oxidative stress, cell wall damaging agents, or SHAM. CONCLUSION: Two adjacent mutations in the SdhB gene conferred different resistance phenotypes to SDHIs in C. cassiicola, which is important for the development of alternative antifungal fungicides and fluopyram resistance management. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Corynespora cassiicola is the causal agent of target spot of several cultivated species, among which cucumber is highlighted for frequent reports of yield losses under greenhouse conditions. Given the difficulties managing this disease due to the lack of information about the resistance of cucumber cultivars, the aim of the present study was to evaluate the response of ten cucumber cultivars to C. cassiicola based on epidemiological components of the disease in a greenhouse. Symptoms of target spot were apparent in all cucumber cultivars from the second day of inoculation of C. cassiicola, demonstrating the short incubation period of the disease and the susceptibility of the crop. The components latent period, number of lesions, lesion diameter, disease severity, number of sporulating lesions, number of spores per affected leaf area and number of spores per sporulating lesion varied according to the cucumber cultivar. The monomolecular model showed the best fit to the number of target spot lesions during the ten days of evaluation, showing differences between cultivars for initial inoculum and disease progression rate parameters. Multivariate analysis with the epidemiological components combined identified three groups of cultivars: one group that was less affected by the disease, represented by Safira and Diplomata cultivars; a second group showing intermediate behaviour, including Valent, Eureka, Taiko, Yamarashi and Darlington cvs., and a third group that was most susceptible to the pathogen and was represented by Soldier, Vulcano and Exocet cvs. Safira and Diplomata cultivars showed low level of susceptibility to target spot and can be recommended for areas with high disease intensity. [ABSTRACT FROM AUTHOR]

Corynespora cassiicola, a fungal plant pathogen with a large host range, causes important damages in rubber tree (Hevea brasiliensis), in Asia and Africa. A small secreted protein named cassiicolin was previously identified as a necrotrophic effector required for the virulence of C. cassiicola in specific rubber tree clones. The objective of this study was to decipher the cassiicolin-mediated molecular mechanisms involved in this compatible interaction. We comparatively analyzed the RNA-Seq transcriptomic profiles of leaves treated or not with the purified cassiicolin Cas1, in two rubber clones: PB260 (susceptible) and RRIM600 (tolerant). The reads were mapped against a synthetic transcriptome composed of all available transcriptomic references from the two clones. Genes differentially expressed in response to cassiicolin Cas1 were identified, in each clone, at two different time-points. After de novo annotation of the synthetic transcriptome, we analyzed GO enrichment of the differentially expressed genes in order to elucidate the main functional pathways impacted by cassiicolin. Cassiicolin induced qualitatively similar transcriptional modifications in both the susceptible and the tolerant clones, with a strong negative impact on photosynthesis, and the activation of defense responses via redox signaling, production of pathogenesis-related protein, or activation of the secondary metabolism. In the tolerant clone, transcriptional reprogramming occurred earlier but remained moderate. By contrast, the susceptible clone displayed a late but huge transcriptional burst, characterized by massive induction of phosphorylation events and all the features of a hypersensitive response. These results confirm that cassiicolin Cas1 is a necrotrophic effector triggering a hypersensitive response in susceptible rubber clones, in agreement with the necrotrophic-effector-triggered susceptibility model. [ABSTRACT FROM AUTHOR]

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Lilacs (Syringa spp.), a genus of trees and shrubs in the Oleaceae, are known for their beautiful, fragrant flowers and are widely cultivated as ornamentals. In September 2017, a new leaf spot disease was observed on S. oblata in the Sui and Tang Ruins Dynasties Botanical Garden in Luoyang, Henan Province, China. Leaf symptoms appeared as small brown lesions at earlier stages, which with age turned into suborbicular brown, faintly zonate and depressed. Fully mature lesions were mostly irregular to circular, concentric rings with taupe and dark brown bands. A total of 12 monoconidial isolates were obtained from S. oblata showing leaf symptoms. Colonies were grey to light brown and darker underneath on potato dextrose agar. Based upon morphological characteristics and multilocus phylogenetic analyses using ITS, TEF1 and RPB2 loci, isolates were identified as Corynespora cassiicola. Pathogenicity tests on leaves produced symptoms matching those described above and the fungus was re‐isolated, confirming Koch's postulates. This study represents the first report of C. cassiicola on lilacs in China. [ABSTRACT FROM AUTHOR]

Rubber tree Corynespora leaf fall (CLF) disease, caused by the fungus Corynespora cassiicola, is one of the most damaging diseases in rubber tree plantations in Asia and Africa, and this disease also threatens rubber nurseries and young rubber plantations in China. C. cassiicola isolates display high genetic diversity, and virulence profiles vary significantly depending on cultivar. Although one phytotoxin (cassicolin) has been identified, it cannot fully explain the diversity in pathogenicity between C. cassiicola species, and some virulent C. cassiicola strains do not contain the cassiicolin gene. In the present study, we report high-quality gapless genome sequences, obtained using short-read sequencing and single-molecule long-read sequencing, of two Chinese C. cassiicola virulent strains. Comparative genomics of gene families in these two stains and a virulent CPP strain from the Philippines showed that all three strains experienced different selective pressures, and metabolismrelated gene families vary between the strains. Secreted protein analysis indicated that the quantities of secreted cell wall-degrading enzymes were correlated with pathogenesis, and the most aggressive CCP strain (cassiicolin toxin type 1) encoded 27.34% and 39.74% more secreted carbohydrate-active enzymes (CAZymes) than Chinese strains YN49 and CC01, respectively, both of which can only infect rubber tree saplings. The results of antiSMASH analysis showed that all three strains encode ~60 secondary metabolite biosynthesis gene clusters (SM BGCs). Phylogenomic and domain structure analyses of core synthesis genes, together with synteny analysis of polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) gene clusters, revealed diversity in the distribution of SM BGCs between strains, as well as SM polymorphisms, which may play an important role in pathogenic progress. The results expand our understanding of the C. cassiicola genome. Further comparative genomic analysis indicates that secreted CAZymes and SMs may influence pathogenicity in rubber tree plantations. The findings facilitate future exploration of the molecular pathogenic mechanism of C. cassiicola. [ABSTRACT FROM AUTHOR]

Corynespora cassiicola (Berk. & Curt.) C.T. Wei is a fungus that occupies several diverse habits from a saprophyte to a parasite of plants, nematodes and humans. As a phytoparasitic fungus, C. cassiicola causes disease in a broad range of plant species worldwide. It causes target spot on cotton (Gossypium hirsutum L.) and Soya bean (Glycine max (L.) Merr.) and is a disease of economic importance. Increasing demand for food and fibre to supply a growing world population requires increasing yields of crops on existing agricultural land while protecting the environment, following the principles of integrated pest management (IPM) strategies. The current review provides a summary of research conducted on C. cassiicola with a special focus on target spot of cotton and Soya bean. The biology and diversity among C. cassiicola isolates are presented. A more detailed discussion on two essential IPM strategies is provided emphasizing their importance in disease management; the risk of fungicide resistance development with the use of fungicides to control target spot, and the need for genetic control with resistant cultivars. [ABSTRACT FROM AUTHOR]

Point mutation G143A in the cytochrome b (Cyt b) protein commonly confers resistance to quinone outside inhibitor (QoI) fungicides in phytopathogenic fungi, including Corynespora cassiicola, which causes cucumber target spot disease. However, the effect of G143A on the binding between the QoI fungicide and the Cyt b protein, and the use of LAMP (loop-mediated isothermal amplification) to detect this point mutation had not been reported previously in C. cassiicola. In this study, the sensitivity of 131 C. cassiicola isolates—collected from Shandong province, China in 2019 and 2020—to pyraclostrobin was determined. The EC50 values ranged from 1.67 to 8.82 µg/mL, and sequencing results showed that all C. cassiicola isolates contained the G143A mutation. Molecular docking results suggested that G143A significantly alters the affinity of pyraclostrobin to the Cyt b protein. Following development of three LAMP primer pairs, the best reaction condition for LAMP analysis was 65 ◦C for 60 min, and the detection limit was 0.01 ng/µL of DNA containing the point mutation. In conclusion, the G143A mutation conferring pyraclostrobin resistance is widespread in C. cassiicola from Shandong province, and the LAMP method can be used to monitor QoI resistance in C. cassiicola caused by the G143A mutation in the field. [ABSTRACT FROM AUTHOR]

Babchi (Psoralea corylifolia) is an anciently known medicinal plant commonly found in sub-tropical and temperate parts of India and China. In January 2023, typical target spot symptoms were observed on the leaves of babchi plants in ornamental gardens at GKVK, Bangalore, India. The distinctive spots were extensively present on the foliage viz., leaves, petiole and stem but prominently in older leaves. Pathogenic isolation, purification and morphological characterisation revealed the associated pathogen belongs to the genus Corynespora. Multilocus sequencing and phylogenetic analysis of internal transcribed spacer (ITS) region, actin (ACT) and calmodulin (Cal) regions confirmed Corynespora cassiicola as the causal organism responsible for target leafspot in babchi. Further, pathogenicity was established by proving Koch's postulates. To the best of our knowledge, this is the first report of C. cassiicola causing target leaf spot on babchi plant in India. • Corynespora cassiicola , an emerging pathogen was identified on leaves of babchi (Psoralea corylifolia) causing target leafspot at medicinal gardens, Bangalore, India. • Preliminary microscopic examination followed by isolation and purification accompanied with morphological characterisation revealed that the associated pathogen belongs to the genus Corynespora. • Concatenated multi-gene (ITS, Actin and calmodulin genes) evolutionary analysis confirmed the causal organism as Corynespora cassiicola. • This study signifies the first documentation of C. cassiicola associated with target leafspot of babchi under Indian conditions. [ABSTRACT FROM AUTHOR]

Leaf spot caused by Corynespora cassiicola was observed on plants of Assam indigo (Strobilanthes flaccidifolius) in Higashi village in Okinawa Prefecture, Japan, in October 2019. The fungus isolated from diseased leaves was identified based on morphological characteristics and molecular analysis of the rDNA-ITS region. Inoculation tests using the isolated fungus confirmed Corynespora cassiicola as the causative agent of the disease. To the best of our knowledge, this is the first report of leaf spot disease in Assam indigo caused by C. cassiicola in Japan. Leaf spot, "hanten-byo" in Japanese, is the proposed name of the disease. [ABSTRACT FROM AUTHOR]

Soil microorganisms are well studied for their beneficial effects on plant growth and their impact on biocontrol agents. The production of volatile antifungal compounds emitted from soil fungi is considered to be an effective ability that can be applied in biofumigants in the control of plant diseases. A soil fungus, Trichoderma asperelloides TSU1, was isolated from flamingo flower cultivated soil and identified on the basis of the morphology and molecular analysis of the internal transcribed spacer (ITS), rpb2, and tef1-α genes. To test T. asperelloides TSU1-produced volatile organic compounds (VOCs) with antifungal activity, the sealed plate method was used. The VOCs of T. asperelloides TSU1 inhibited the mycelial growth of fungal pathogens that were recently reported as emerging diseases in Thailand, namely, Corynespora cassiicola, Fusarium incarnatum, Neopestalotiopsis clavispora, N. cubana, and Sclerotium rolfsii, with a percentage inhibition range of 38.88–68.33%. Solid-phase microextraction (SPME) was applied to trap VOCs from T. asperelloides TSU1 and tentatively identify them through gas chromatography–mass spectrometry (GC/MS). A total of 17 compounds were detected in the VOCs of T. asperelloides TSU1, and the dominant compounds were identified as fluoro(trinitro)methane (18.192% peak area) and 2-phenylethanol (9.803% peak area). Interestingly, the commercial 2-phenyethanol showed antifungal activity against fungal pathogens that were similar to the VOCs of T. asperelloides TSU1 by bioassay. On the basis of our study’s results, T. asperelloides TSU1 isolated from soil displayed antifungal abilities via the production of VOCs responsible for restricting pathogen growth. [ABSTRACT FROM AUTHOR]

Corynespora leaf spot (CLS) is one of the most important diseases in sesame and is caused by a fungal pathogen, Corynespora cassiicola. In this study, we investigated the role of cell‐wall‐degrading enzymes (CWDEs) in the process of pathogen infection and aimed to identify the enzyme that exerts positive effect. Corynespora cassiicola was inoculated in liquid culture and in sesame leaf. At 7 days postinoculation, CWDEs including polygalacturonase (PG), cellulase (CL), neutral xylanase (NEX) and laccase (LC) were detected in the supernatant and leaf extracts inoculated with Corynespora cassiicola. The result showed that the activities of LC and NEX were higher in liquid culture, while the activities of CL and PG were lower. In the sesame leaf infected by Corynespora cassiicola, the activity of NEX was the highest, those of CL and LC were the second highest and that of PG was the weakest, which indicated that NEX was the key enzyme in the process of sesame infection by Corynespora cassiicola. Secondly, the activities of the CWDEs secreted by Corynespora cassiicola were disparate in different sesame varieties. CWDEs activities of cultivar Jz were generally higher than cultivar Hn, and the activity change curve of Jz was also steeper than that of Hn. This indicates that the resistance mechanism of Hn may inhibit the activities of CWDEs and that the appearance and expansion of leaf necrosis spot is related to the comprehensive accumulation and action of various CWDEs. This is the first report investigating the association between CWDEs and pathogenesis of Corynespora cassiicola, causing Corynespora leaf spot in sesame. [ABSTRACT FROM AUTHOR]

Target Spot is an important disease in soybean caused by the necrotrophic fungus Corynespora cassiicola. Recently, this fungus has gained importance in large crops such as soybeans and for its insensitivity fungicides reports. In this study, three assays were carried out with different application treatments in order to evaluate fungicide applications to control Target Spot and their interference on soybean productivity. Different application treatments were tested including fungicide products, doses, mixtures and number of applications, as well as estimate the application's economic viability. Cultivar TMG 2378 IPRO was used and the applications were performed with a CO2 sprayer pressurized in a randomized block design with four replications. The harvest of 2.7 m² useful area in the plot center was carried out with a stationary plot harvester and the yield was estimated for kg ha-1. For an economic analysis of the application treatments, the soybeans sale was considered at a fixed price of US$ 264 t-1, while the operating cost at a value of US$ 8. The fungicides spraying cost was estimated in kg of grains ha-1 based on the average of two budgets made. The fungicide mixtures bixafen+prothioconazole+trifloxystrobin+mancozeb and trifloxystrobin+ prothioconazole+mancozeb presented both yield increase and economic viability compared to control. [ABSTRACT FROM AUTHOR]

Corynespora leaf spot is a fungal infection caused by the fungal pathogen “Corynespora cassiicola. The bibliometric analysis had been conducted to understand the active authors, organizations, journals, and countries involved in the research domain of “Corynespora leaf spot”. All published articles related to “Corynespora leaf spot” from “Scopus”, were analyzed using the VOS viewer to develop analysis tables and visualization maps. This article had set the objective to consolidate the scientific literature regarding the “Corynespora leaf spot” and also to find out the trends related to the same. The most active journals in this research domain were identified as Pest Management Science, Plant Pathology, and Plant Disease. The leading countries of the research domain are the United States of America, China, and Japan. The leading organizations engaged in the research regarding Corynespora leaf spot was The Federal University of Viçosa of Brazil. The most active authors who had made valuable contributions related to Corynespora leaf spot disease were Barreto R.W. Ishii H. and Liu F. [ABSTRACT FROM AUTHOR]

Corynespora leaf spot caused by Corynespora cassiicola has become an important disease affecting cucumber. To provide the basis of biological research for exploring different resistance mechanisms of C. cassiicola to boscalid, the biological characteristics and environmental fitness of C. cassiicola with different types of resistance to boscalid were determined in this study. A total of 24 strains of C. cassiicola collected from different regions with different resistant types to boscalid were randomly selected. Seven types of resistant mutants cross-resistance to several different succinate dehydrogenase inhibitors (SDHIs) were analyzed and whether the mutants could inherite stably after cultivated nine generations on PDA plates without any fungicides selection pressure were determined. Meanwhile, the biological characteristics of resistant mutants under different carbon and nitrogen sources, temperature and other conditions were also determined to evaluate the fitness of resistant mutants under different environmental conditions. The results indicated that only SdhB-H278Y and SdhB-H278R mutants showed negative cross-resistance between boscalid and fluopyram, while drug resistance in all strains of the different mutation types could be inherited stably. Pathogenicity of different mutation types strains were discrepant, and the SdhD-D95E mutants had the strongest pathogenicity. The most favorable carbon source for the growth of all resistant mutants was maltose, and no discrepancy was showed in the effects of different nitrogen sources. The most optimal growth temperature range of each mutant strain was 25-30 ℃, while SdhD-D95E mutants grew faster than other mutants at temperatures greater than 30 ℃. In the study of heat resistance, the resistant mutants were not able to survive after treated at 65 ℃ for 45 min. At the same time, the mutant could grow normally under the condition of 60 ℃, while the sensitive strain could not. The mycelium growth rate of SdhDD95E mutants were faster than that of other mutant strains, while SdhB-H278Y mutants were slower than that of other mutant strains under treatment with various concentrations of NaCl. Glucose was important to the growth of SdhB-H278R mutants. The results showed that the biological characteristics and fitness of C. cassiicola with different boscalid-resistance were discrepant. The adaptability of SdhD-D95E mutants was improved, indicating that the mutant had stronger competitiveness in the field and was easy to form a dominant population. [ABSTRACT FROM AUTHOR]

Roselle (Hibiscus sabdariffa L.) leaf and calyx spot induced by Corynespora cassiicola is one of the most important diseases that limit production, processing, and commercial use of this crop. The temporal progress of this disease was followed in four production locations in Guerrero, Mexico, during the 2014 and 2015 cycles. Disease incidence and severity were evaluated every 10 days through the 173-day production cycles. Epidemics were evaluated using the area under disease progress curves (AUDPCs) and Weibull model parameters. The highest severity and epidemic rate in calyces and leaves was registered in San Miguel, while the lowest was recorded in Xalpatlahuac in both cycles. Disease incidence in calyces was lower in Xalpatlahuac during both evaluation cycles and in leaves only in the 2015 cycle. The Weibull model properly described the epidemics (r = 0.93–0.99). The highest periods of epidemic growth in leaves were registered during flowering, development of calyces and foliar senescence; and in calyces during their physiological maturation and harvest. Severity on leaves and calyces was correlated with temperature from 20 to 30 °C (r = 0.80–1.0) and relative humidity higher than 90% (r = 0.80–1.0) (p < 0.05). The calyces severity was related to the leaves severity (r = 0.90–0.97) (p < 0.01). [ABSTRACT FROM AUTHOR]

An increasing interest in the development of products of natural origin for crop disease and pest control has emerged in the last decade. Here we introduce a new family of strawberry acyl glycosides (SAGs) formed by a trisaccharide (GalNAc-GalNAc-Glc) and a monounsaturated fatty acid of 6 to 12 carbon atoms linked to the glucose unit. Application of SAGs to Arabidopsis thaliana (hereafter Arabidopsis) plants triggered a transient oxidative burst, callose deposition and defense gene expression, accompanied by increased protection against two phytopathogens, Pseudomonas viridiflava and Botrytis cinerea. SAGs-induced disease protection was also demonstrated in soybean infected with the causal agent of target spot, Corynespora cassiicola. SAGs were shown to exhibit important antimicrobial activity against a wide-range of bacterial and fungal phytopathogens, most probably through membrane destabilization, and the potential use of SAGs as a biofungicide for postharvest disease protection was demonstrated on lemon fruits infected with Penicillium digitatum. Plant growth promotion by application of SAGs was shown by augmented primary root elongation, secondary roots development and increased siliques formation in Arabidopsis, whereas a significant increment in number of seed pods was demonstrated in soybean. Stimulation of radicle development and the induction of an auxin-responsive reporter system (DR5::GUS) in transgenic Arabidopsis plants, suggested that SAGs-stimulated growth at least partly acts through the auxin response pathway. These results indicate that strawberry fatty acid glycosides are promising candidates for the development of environmental-friendly products for disease management in soybean and lemon. [ABSTRACT FROM AUTHOR]

The roselle (Hibiscus sabdariffa) is affected by severe diseases such as blight and spotting of the calyx (MCJ). The objective was to study the relationships between seasonal fluctuation of Corynespora and Coniella spores, pathogenic stains and blight of chalices and leaves, weather conditions and severity (MCJ) in Ayutla, Gro. Mexico. The spores were monitored, in two cycles, the fungi were isolated and the morphological and molecular identification of Coniella was performed, the study focused on pathogens reported in Mexico. The pathogenicity tests with C. diplodiella and C. cassiicola confirmed very similar symptoms between both fungi. Coniella was the most abundant (48%) and with least amount Corynespora (8.7%). The spore dynamics had a monthly and weather related fluctuation. The population dynamics of spores was closely related to the climate. The maximum and average temperatures (°C) and average global radiation (W/m²) showed significant positive correlations with the abundance of Coniella spores and the total spores, while precipitation (mm), minimum temperature, wind speed maximum (Km hr-1) and hours of solar radiation, their relations were negative with the fluctuations of Corynespora spores. The severity of leaf and calyx staining was positively and significantly correlated with the number of spores captured. [ABSTRACT FROM AUTHOR]

Corynespora leaf spot, caused by Corynespora cassiicola , is a foliar disease in cucumber. While the application of quinone outside inhibitors (QoIs) is an effective measure for disease control, it carries the risk of resistance development. In our monitoring of trifloxystrobin resistance from 2008 to 2020, C. cassiicola isolates were categorized into three populations: sensitive isolates (S, 0.01 < EC 50 < 0.83 μg/mL), moderately resistant isolates (MR, 1.18 < EC 50 < 55.67 μg/mL), and highly resistant isolates (HR, EC 50 > 56.98 μg/mL). The resistance frequency reached up to 90% during this period, with an increasing trend observed in the annual average EC 50 values of all the isolates. Analysis of the CcCytb gene revealed that both MR and HR populations carried the G143A mutation. Additionally, we identified mitochondrial heterogeneity, with three isolates carrying both G143 and A143 in MR and HR populations. Interestingly, isolates with the G143A mutation (G143A-MR and G143A-HR) displayed differential sensitivity to QoIs. Further experiments involving gene knockout and complementation demonstrated that the major facilitator superfamily (MFS) transporter (CcMfs1) may contribute to the disparity in sensitivity to QoIs between the G143A-MR and G143A-HR populations. However, the difference in sensitivity caused by the CcMfs1 transporter is significantly lower than the differences observed between the two populations. This suggests additional mechanisms contributing to the variation in resistance levels among C. cassiicola isolates. Our study highlights the alarming level of trifloxystrobin resistance in C. cassiicola in China, emphasizing the need for strict prohibition of QoIs use. Furthermore, our findings shed light on the occurrence of both target and non-target resistance mechanisms associated with QoIs in C. cassiicola. [Display omitted] • The annual average EC 50 value of C. cassiicola to trifloxystrobin has gradually increased in China. • Isolates carrying the G143A mutation exhibit differential sensitivity to QoIs. • Both target and non-target resistance mechanisms of QoIs were found in Corynespora cassiicola. [ABSTRACT FROM AUTHOR]

The cucumber target spot, caused by Corynespora cassiicola , is a major cucumber disease in China. Mefentrifluconazole, a new triazole fungicide, exhibits remarkable efficacy in controlling cucumber target spot. However, the resistance risk and mechanism remain unclear. In this study, the inhibitory activity of mefentrifluconazole against 101 C. cassiicola isolates was determined, and the results indicated that the EC 50 values ranged between 0.15 and 12.85 μg/mL, with a mean of 4.76 μg/mL. Fourteen mefentrifluconazole-resistant mutants of C. cassiicola were generated from six parental isolates in the laboratory through fungicide adaptation or UV irradiation. The resistance was relatively stable after ten consecutive transfers on a fungicide-free medium. No cross-resistance was observed between mefentrifluconazole and pyraclostrobin, fluopyram, prochloraz, mancozeb, or difenoconazole. Investigations into the biological characteristics of the resistant mutants revealed that six resistant mutants exhibited an enhanced compound fitness index (CFI) compared to the parental isolates, while others displayed a reduced or comparable CFI. The overexpression of CcCYP51A and CcCYP51B was detected in the resistant mutants, regardless of the presence or absence of mefentrifluconazole. Additionally, a two-way mixture of mefentrifluconazole and prochloraz at a concentration of 7:3 demonstrated superior control efficacy against the cucumber target spot, achieving a protection rate of 80%. In conclusion, this study suggests that the risk of C. cassiicola developing resistance to mefentrifluconazole is medium, and the overexpression of CcCYP51A and CcCYP51B might be associated with mefentrifluconazole resistance in C. cassiicola. The mefentrifluconazole and prochloraz two-way mixture presented promising control efficacy against the cucumber target spot. [Display omitted] • The resistance risk of C. cassiicola to mefentrifluconazole is medium. • CcCYP51A and CcCYP51B were overexpressed in mefentrifluconazole-resistant C. cassiicola mutants. • Mefentrifluconazole and prochloraz two-way mixture presented promising control efficacy. [ABSTRACT FROM AUTHOR]

Cucumber corynespora leaf spot, caused by Corynespora cassiicola , is the primary disease of cucumber leaves in greenhouses in China. Fludioxonil is a phenylpyrrole fungicide that inhibits C. cassiicola growth. We studied the sensitivity of 170 isolates of C. cassiicola to fludioxonil and evaluated resistance risk. All of the isolates were sensitive to fludioxonil. The EC 50 values ranged from 0.082 to 0.539 μg/mL with a mean of 0.207 ± 0.0053 μg/mL. Laboratory-created mutants with a high resistance factor to fludioxonil were genetically stable after 10 transfers and showed positive cross-resistance to iprodione and procymidone but not to azoxystrobin, carbendazim, pydiflumetofen, and prochloraz. There was no significant difference in mycelial growth and temperature adaptation between the mutant s and the sensitive isolates, except for pathogenicity and sporulation. The resistant isolates accumulated less glycerol than their parental isolates and were more sensitive to osmotic stress. The histidine kinase activity of the sensitive isolates was significantly inhibited compared to that of the resistant mutants. Sequence alignment of the histidine kinase gene CCos revealed that the mutants RTL4, RXM5, and RFS102 had point mutations at different sites that resulted in amino acid changes at G934E, S739F, and A825P in the CCos protein. The mutant RFS102 had an alanine deletion at site 824. After fludioxonil treatment, CCos expression by RFS20 was significantly lower than that of the parental isolate. Our findings demonstrate that C. cassiicola exhibits moderate resistance to fludioxonil. [Display omitted] • Fludioxonil has a strong inhibitory activity against Corynespora cassiicola. • The adaptability of the fludioxonil-resistant mutants in pathogenicity and osmotic stress decreased. • The resistance mechanism of fludioxonil is associated with the point mutation of CCos. [ABSTRACT FROM AUTHOR]

• PME gene family comprises 3 major clades with up to 5 members per genome. • PME1 and PME2 clades shaped by duplications and recurring gene retention. • PME3 clade characterized by biased gene loss. • Corynespora cassiicola PME genes exhibit varying levels of expression during soybean infection. • A member of the Cc_PME2.3 sub-clade reached the highest relative expression level. Once deposited in the plant cell wall, pectin undergoes demethylesterification by endogenous pectin methylesterases (PMEs), which play various roles in growth and development, including defense against pathogen attacks. Pathogen PMEs can alter pectin's methylesterification pattern, increasing its susceptibility to degradation by other fungal pectinases and thus playing a critical role as virulence factors during early infection stages. To investigate the evolutionary history of PMEs in the Dothideomycetes class of fungi, we obtained genomic data from 15 orders (79 species) and added genomic data from 61 isolates of Corynespora cassiicola. Our analyses involved maximum likelihood phylogenies, gene genealogies, and selection analyses. Additionally, we measured PME gene expression levels of C. cassiicola using soybean as a host through RT-qPCR assays. We recovered 145 putative effector PMEs and 57 putative non-effector PMEs from across the Dothideomycetes. The PME gene family exhibits a small size (up to 5 members per genome) and comprises three major clades. The evolutionary patterns of the PME1 and PME2 clades were largely shaped by duplications and recurring gene retention events, while biased gene loss characterized the small-sized PME3 clade. The presence of five members in the PME gene family of C. cassiicola suggests that the family may play a key role in the evolutionary success of C. cassiicola as a polyphagous plant pathogen. The haplogroups Cc_PME1.1 and Cc_PME1.2 exhibited an accelerated rate of evolution, whereas Cc_PME2.1, Cc_PME2.2, and Cc_PME2.3 seem to be under strong purifying selective constraints. All five PME genes were expressed during infection of soybean leaves, with the highest levels during from six to eight days post-inoculation. The highest relative expression level was measured for CC_29_g7533, a member of the Cc_PME2.3 clade, while the remaining four genes had relatively lower levels of expression. [ABSTRACT FROM AUTHOR]

Fresh-market tomatoes bring in $400-$500 million annually as the third most valuable crop in the state. Defoliation and fruit damage from target spot, caused by Corynespora cassiicola, can have serious economic implications for growers. This new 5-page publication of the UF/IFAS Plant Pathology Department, written by Keevan MacKenzie, Jessica Chitwood, Gary Vallad, and Sam Hutton, reviews symptoms and epidemiology of the disease and provides current management recommendations. https://edis.ifas.ufl.edu/pp351

The fungus causing target spot disease, Corynespora cassiicola (Berk. & M. A. Curtis) C. T. Wei, poses an increasing threat to watermelon (Citrullus lanatus), muskmelon (Cucumis melo), and cucumber (Cucumis sativus); the most economically important cucurbit crops grown in China. An understanding of the molecular mechanisms underlying the pathogenicity of C. cassiicola is essential for the development of new strategies to control this disease-causing fungus. Agrobacterium tumefaciens -mediated transformation (ATMT) might be useful to obtain transformants of C. cassiicola , for the ultimate identification of genes involved in pathogenicity. In the present work, we established and optimized an ATMT protocol using A. tumefaciens strain AGL-1 carrying the vector pATMT1 for C. cassiicola. Efficiency of ATMT was 102–148 transformants per 106 conidia and successive subculturing of transformants on non-selective and selective media demonstrated that the integrated transfer (T)-DNA was stably inherited in C. cassiicola transformants. The integration of the hygromycin B phosphotransferase (hph) gene into C. cassiicola was validated by PCR and Southern blot analyses, which revealed that nearly 90 % of the transformants contained single-copy T-DNA. The transformants with altered phenotypes were characterized. Three of these transformants completely lost pathogenicity and other three showed strongly impaired pathogenicity relative to the Cc -GX strain on muskmelon leaves. These results strongly suggest that ATMT may be used as a molecular tool for identifying genes relevant to pathogenicity in the fungus C. cassiicola , an emerging threat to several agronomically important plants in China. • Corynespora cassiicola causes target spot disease in cucurbits grown in China. • Agrobacterium tumefaciens -mediated transformation (ATMT) was established and optimized for C. cassiicola. • Culturing of transformants on non-selective and selective media showed the inserted DNA was stably inherited. • Three transformants completely lost pathogenicity on muskmelon leaves. • This is the first report of successful ATMT in C.cassiicola. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlight • Trichoderma spirale T76-1 inhibit mycelial growth of leaf spot fungi in vitro. • Trichoderma spirale T76-1 release volatile antifungal compounds to inhibit leaf spot fungi. • β- 1,3-Glucanase and chitinase produced by Trichoderma spirale T76-1 cause morphological change on mycelia of leaf spot fungi. • Application of Trichoderma spirale T76-1 spore suspension reduce disease severity index in lettuce. Abstract Lettuce (Lactuca sativa) is an edible leafy vegetable used in diverse recipes. The disease known as leaf spot leads to plant death and is caused Corynespora cassiicola or Curvularia aeria. In this study, 5 selected isolates of Trichoderma spp. were assessed for their antifungal activities against C. cassiicola and C. aeria. Trichoderma spirale T76-1 was superior in inhibiting the mycelial growth of C. cassiicola and C. aeria by 84.68% and 93.03%, respectively, in dual culture assays. In a volatile antifungal bioassay T. spirale T76-1 suppressed the growths of C. cassiicola and C. aeria by 41.29% and 42.35%, respectively. GC/MS profiling revealed the presence of antifungal compounds, including alcohol and pyran. Poisoned food technique showed that the cell-free culture filtrate of T. spirale T76-1 inhibited C. cassiicola and C. aeria by 48.47% and 51.67%, respectively. The enzyme activities of β -1,3-glucanase and chitinase in the cell-free culture filtrate were 10.13 and 0.93 U mL−1, respectively. Scanning electron microscopy of mycelia incubated with cell-free culture filtrate of T. spirale T76-1 showed abnormal shapes in both pathogens. Leaf spraying with a spore suspension of T. spirale T76-1 suppressed disease incidence by up to 58–62% compared to control (96–98% penetration, inoculation with pathogen alone). These findings reveal that competition, volatile antifungals, and enzyme activities are mechanisms involved in the biocontrol of leaf spot in lettuce by T. spirale T76-1. [ABSTRACT FROM AUTHOR]

Abstract Target leaf spot caused by Corynespora cassiicola is an economically important foliar disease on cucumber. In recent years, this disease has caused a serious problem on greenhouse-cultivated cucumber in China. In this study, to explore the characteristics and possible causes of heavy occurrence of the disease, we monitored the resistance of C. cassiicola strains from different provinces of China to benzimidazole and quinone outside inhibitor (QoI) fungicides. The results from sequence comparison of target genes β-tubulin and Cytb of 619 C. cassiicola strains indicate that resistance frequency to benzimidazoles and QoIs is up to 100%. Furtherly, molecular resistance mechanism of C. cassiicola to benzimidazoles and QoIs was analysed. One single mutation E198A and three double mutations E198A&M163I, E198A&F167Y and E198A&F200S were observed in target gene β-tubulin , which confers resistance to benzimidazoles. To our knowledge, this is the first report that double mutations of β-tubulin confer resistance to benzimidazoles in filamentous fungi. Compared with single mutation E198A, three double mutations significantly decreased sensitivity to benzimidazoles. Moreover, significant difference of sensitivity to benzimidazoles was observed among three double mutations. These mutation genotypes of β-tubulin have different geographical distribution and the mutation E198A&M163I is prevalent, occupying for 63.94%. In addition, strong cross resistance patterns between carbendazim, benomyl and thiabendazole were observed in C. cassiicola strains conferring different β-tubulin mutations. For QoI resistance, the only mutation G143A of Cytb was detected in tested 619 C. cassiicola strains. Strong positive cross resistance was observed when comparing the EC 50 values of sensitive and resistant strains of C. cassiicola for six intrinsically different QoIs such as azoxystrobin, fluoxastrobin, pyraclostrobin, fenaminstrobin, picoxystrobin and coumoxystrobin. Taken together, all the results not only provide novel insights into understanding resistance mechanism to benzimidazoles and QoIs in filamentous fungi, but also provide some important references for resistance management of target leaf spot on cucumber. Graphical abstract Unlabelled Image Highlights • It is the first report that double mutations of β-tubulin cause benzimidazole resistance in filamentous fungi. • Double mutations E198A&M163I, E198A&F167Y and E198A&F200S of β-tubulin were detected in C. cassiicola. • Double mutations of β-tubulin cause super-resistance of C. cassiicola to benzimidazoles in comparison to single mutation. • Resistance frequency of C. cassiicola from cucumber in greenhouse to benzimidazoles and QoIs is up to 100% in China. • The G143A mutation of Cytb was detected in QoI-resistant C. cassiicola strains in China. [ABSTRACT FROM AUTHOR]

Corynespora cassiicola is an important plant pathogen with a wide host range. We investigated pathogenic and genetic variation among 69 C. cassiicola isolates from 16 hosts in China. Based on the inter-primer binding sites (iPBS)-retrotransposons, we selected five iPBS primers to analyse the genetic variability of these isolates. All isolates were clustered in two genetic clades (IG1 and IG2). Forty-four C. cassiicola isolates were selected from the collection to investigate their pathogenic profiles. Based on the results of the pathogenicity analysis, these 44 isolates were divided into two pathogenicity groups (PG1 and PG2). A correlation between the genetic and pathogenicity groups was observed in the phylogenetic tree obtained with the iPBS markers, whereas the isolates from rubber tree were clustered in an independent clade. A total of 72 bands were observed, of which 68 were polymorphic (94.44%). The Nei's genetic identity index of the 16 host populations varied from 0.5035 to 0.9661. The mean Nei's gene diversity index (H = 0.3042) and the mean Shannon's information index (I = 0.4598) at the species level were higher than at the population level, suggesting that the genetic diversity within the populations was greater than among the populations. The Nei's GST (0.7895) and gene flow (0.1333) showed more considerable genetic differentiation among populations and few gene exchanges. The pathogenicity and molecular marker analyses revealed there was a high level of genetic differentiation and diversity in the C. cassiicola isolates studied. [ABSTRACT FROM AUTHOR]

Corynespora blight, caused by Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei, has become an important disease affecting cucumber in China. Its management mainly depends on fungicides; however, no research has been conducted to assess the sensitivity of C. cassiicola in China to boscalid. a succinate dehydrogenase inhibitor (SDHI). To facilitate boscalid resistance monitoring, baseline sensitivity was established. The EC50 value (i.e., the concentration that results in 50% mycelial growth inhibition) frequency distribution was unimodal with a right-hand tail; with the means 0.95 ± 0.51 µg/ml and the range 0.03 to 2.85 µml. We then assessed the sensitivity of C. cassiicola to boscalid using discriminatory doses and EC50 values. In total, 27.8% of the 798 isolates were resistant, distributed in five provinces and two municipalities. Thirty-seven isolates with different resistance levels to boscalid were also evaluated for their sensitivity to carboxin, tluopyram, and penthiopyrad. Seven SDHI resistance patterns were observed (i.e., 1: BosMR FluoMRPenLRCarSS; BosVHRFluoSSPenMRCarR; III: BosLRFluoMRPenLRCarR; IV: BosMRFluoMRPenMRCarR; V: BosHRFluoMRPenHRCarR; VI: BosHRFluoHRPenHRCarR; and VII: BosHRFluoSSPenLR CarR, VHR: very highly resistant; HR: highly resistant; MR: moderately resistant; LR: low resistant; R: resistant; SS: supersensitive), corresponding to seven mutations in sdhB/C/D genes, respectively. [ABSTRACT FROM AUTHOR]

Considering the importance of target spot, caused by Corynespora cassiicola, to impact soya bean yield, this study investigated the C. cassiicola‐induced perturbations in the photosynthesis of soya bean plants from cultivars Fundacep 59 (moderately resistant) and TMG 132 (susceptible) by examining the chlorophyll (Chl) a fluorescence parameters and imaging and the photosynthetic pigment pools. The area under disease progress curve decreased by 38% for plants from cultivar Fundacep 59 in comparison with plants from cultivar TMG 132. The concentration of total Chla+b significantly increased by 16% and the Chla+b/carotenoids ratio significantly decreased by 11% for plants from cultivar Fundacep 59 in comparison with plants from cultivar TMG 132. Significant decreases of 31% and 8%, respectively, for the concentration of Chla+b and the Chla+b/carotenoids ratio occurred for inoculated plants in comparison with noninoculated ones regardless of the cultivar. As target spot developed, the values of maximal photosystem II quantum yield (Fv/Fm), effective photosystem II quantum yield [Y(II)], quantum yield of regulated energy dissipation [Y(NPQ)] and quantum yield of nonregulated energy dissipation [Y(NO)] increased, especially for plants from cultivar TMG 132. There were positive correlations of area under disease progress curve (AUDPC) with both Y(NPQ) and Y(NO) regardless of the cultivar. For cultivar TMG 132, the correlation between AUDPC and the electron transport rate was negative. Based on the analysis of the Chl a fluorescence, it was possible to elucidate the enormous potential of target spot to impair the functionality on the photosynthetic apparatus that may help the plants to invest in metabolic pathways involved in host defence responses. [ABSTRACT FROM AUTHOR]

Target spot, caused by Corynespora cassiicola, has recently emerged as a problematic foliar disease of cotton. This pathogen causes premature defoliation during boll set and maturation that can subsequently impact yield, and on certain cotton cultivars loss can be substantial. This study sought to better understand target spot epidemics and disease-incited yield losses on cotton. In order to establish a range of disease, varying numbers of fungicide applications were made to each of two cotton cultivars in each of four site-years. Target spot intensity was rated over several dates beginning in late July or early August and continuing into September. Yield of seed plus lint (seed cotton) was recorded at harvest. When analyzed across cultivars, a second or third fungicide application increased yield compared with no treatment. Lack of significant yield response with a single fungicide application may have been due to timing of that application which preceded disease onset. The cultivar PhytoGen 499 WRF had consistently greater defoliation than any of the three Deltapine cultivars grown in each site-year. However, yields of both cultivars responded similarly to the fungicide regimes. Yield loss models based on late August defoliation were only predictive at site-years where conditions favored target spot development, i.e., abundant rain and moderate temperatures. Epidemic development fit the Gompertz growth model better than it did a logistic model. Knowledge of the underlying mathematical character of the epidemiology of target spot will prove useful for development of a predictive model for the disease. [ABSTRACT FROM AUTHOR]

• NJC41 inhibited C. cassiicola mycelial growth and spore germination. • NJC41 showed high colonization ability in soybean pods. • NJC41 secreted antifungal phenethyl alcohol and competed for nutrients and space. • NJC41 reduced target spot symptoms in vivo. • The first method for the biocontrol of C. cassiicola in soybean is reported. Corynespora cassiicola is a hazardous fungal pathogen that causes target spot disease in soybean. Numerous resistant C. cassiicola strains have emerged during recent years, leading to uncontrolled spreads and enormous economic losses in several soybean production areas. For these reasons, new methods for the control of this pathogen are urgently needed. In this study, a new Meyerozyma caribbica strain, NJC41, was isolated from C. cassiicola -infected soybean plants in China and identified by ITS and LSU sequencing. NJC41 inhibited C. cassiicola mycelial growth, and showed high colonization ability in soybean pods, maintaining its population for one week. NJC41 produced antifungal phenethyl alcohol, which was detected at 44.6 μg/mL in NJC41 secretions, and competed for space and nutrients with C. cassiicola. Curative application of 1 × 109 cells/mL NJC41 reduced C. cassiicola symptoms by 47.1%, providing higher curative efficacy than commercial fungicide carbendazim (29.8% lesion length inhibition). This study reveals the first biocontrol method for the management of target spot disease in soybean. [ABSTRACT FROM AUTHOR]

A new isopimarane-type diterpene glycoside, named hypomonticuside (1), was isolated from the BuOH-soluble fraction of the liquid fermentation of an endophytic fungus Corynespora smithii, derived from the stems of Ardisia cornudentata Mez (Myrsinaceae). The structure of 1 was elucidated by spectroscopic methods, including UV, IR, HR-ESI-MS, and extensive 1D and 2D NMR techniques. [ABSTRACT FROM AUTHOR]

Corynespora cassiicola is a destructive plant-pathogenic fungus causing widespread target spot epidemics, including outbreaks on cotton, soybean, and tomato in the southeastern United States. Previous studies revealed that populations from the three hosts are genetically distinct and host specialized. Although variation in aggressiveness to cotton and tomato were observed, no genetic diversity was detected within populations sampled from each of these hosts. We aimed to gain a better understanding of the emerging target spot epidemics by developing microsatellite markers for C. cassiicola to assess genetic variation, population structure, and to infer modes of reproduction and mechanisms of dispersal. Two hundred sixty-five isolates from cotton, soybean, tomato, and other host plants were genotyped with 13 microsatellite markers. Genotypic diversity revealed genetic variation within each of the populations collected from different hosts, with the population from cotton dominated by clonal genotypes and showing the least genetic diversity. In addition, C. cassiicola populations on different host species were genetically distinct and structured based on host species. No association between genetic and geographic distances was identified in the tomato populations, and the association in cotton populations was low. However, significant regional geographic structure was detected in the soybean populations of C. cassiicola. These results further support previous findings of introduced host specialized isolates or the evolution of more aggressive strains on each host. The lack of geographic structure suggests that the clones on cotton and tomato spread rapidly, or similar founder populations were established by human-mediated dispersal, and that dispersal is not limited. However, regional geographic structure of populations on soybean suggests limited dispersal among more established populations of C. cassiicola, or genetic differences in founder populations that colonized different geographic areas. [ABSTRACT FROM AUTHOR]

Purpose: CARD9 deficiency is an inborn error of immunity that predisposes otherwise healthy humans to mucocutaneous and invasive fungal infections, mostly caused by Candida, but also by dermatophytes, Aspergillus, and other fungi. Phaeohyphomycosis are an emerging group of fungal infections caused by dematiaceous fungi (phaeohyphomycetes) and are being increasingly identified in patients with CARD9 deficiency. The Corynespora genus belongs to phaeohyphomycetes and only one adult patient with CARD9 deficiency has been reported to suffer from invasive disease caused by C. cassiicola. We identified a Colombian child with an early-onset, deep, and destructive mucocutaneous infection due to C. cassiicola and we searched for mutations in CARD9.Methods: We reviewed the medical records and immunological findings in the patient. Microbiologic tests and biopsies were performed. Whole-exome sequencing (WES) was made and Sanger sequencing was used to confirm the CARD9 mutations in the patient and her family. Finally, CARD9 protein expression was evaluated in peripheral blood mononuclear cells (PBMC) by western blotting.Results: The patient was affected by a large, indurated, foul-smelling, and verrucous ulcerated lesion on the left side of the face with extensive necrosis and crusting, due to a C. cassiicola infectious disease. WES led to the identification of compound heterozygous mutations in the patient consisting of the previously reported p.Q289* nonsense (c.865C > T, exon 6) mutation, and a novel deletion (c.23_29del; p.Asp8Alafs10*) leading to a frameshift and a premature stop codon in exon 2. CARD9 protein expression was absent in peripheral blood mononuclear cells from the patient.Conclusion: We describe here compound heterozygous loss-of-expression mutations in CARD9 leading to severe deep and destructive mucocutaneous phaeohyphomycosis due to C. cassiicola in a Colombian child. [ABSTRACT FROM AUTHOR]

Corynespora cassiicola is a ubiquitous fungus causing emerging plant diseases worldwide, including target spot of cotton, soybean, and tomato, which have rapidly increased in incidence and severity throughout the southeastern United States. The objectives of this study were to understand the causes for the emerging target spot epidemics in the United States by comparing phylogenetic relationships of isolates from cotton, tomato, soybean, and other crop plants and ornamental hosts, and through the determination of the host range of isolates from emerging populations. Fifty-three isolates were sampled from plants in the southeastern United States and 1,380 nucleotides from four nuclear loci were sequenced. Additionally, sequences of the same loci from 23 isolates representing each of the distinct lineages of C. cassiicola described from previous studies were included. Isolates clustered based on host of origin, regardless of the geographic location of sampling. There was no genetic diversity detected among isolates from cotton, which were genetically distinct from isolates from other host species. Furthermore, pathogenicity and virulence assays of 40 isolates from various hosts onto cotton, soybean, tomato, and cucumber showed that isolates from cotton were more aggressive to cotton than those from other hosts. Soybean and tomato were most susceptible to isolates that originated from the same host, providing evidence of host specialization. These results suggest that emerging target spot epidemics in the United States are caused by either the introduction of host-specific isolates or the evolution of more aggressive strains on each host. [ABSTRACT FROM AUTHOR]

Currently, fungicide application in soybean production accounts for an important amount of global pesticide use, and it is therefore most desirable to find new healthier and more environmental friendly alternatives for the phytosanitary management in this crop. In this study, we present convincing evidence for effective induction of disease protection by the agricultural biostimulant PSP1, a formulation based on the plant-defense eliciting activity of the fungal protease AsES (Acremonium strictum elicitor subtilisin), in multiple field trials in Argentina. PSP1 was shown to combine well with commercial spray adjuvants, an insecticide, a herbicide and fungicides used in Argentinian soybean production without losing any defense-inducing activity, indicating an easy and efficient adaptability to conventional soybean production and disease management in the region. Results from multiple soybean field trials conducted with different elite genotypes at several locations during two consecutive growing seasons, showed that PSP1 is able to induce an enhanced pathogen defense which effectively reduced late season disease (LSD) development in field-grown soybean. This defense response seems to be broad-range as disease development was clearly reduced for at least three different fungi causing LSDs in soybean (Septoria glycines, Cercospora kikuchii and Cercospora sojina). It was noteworthy that application of PSP1 in soybean alone gave a similar protection against fungal diseases as compared to the commercial fungicides included in the field trials and that PSP1 applied together with a fungicide at reproductive stages enhanced disease protection and significantly increased grain yields. PSP1 is the first example of an elicitor-based strategy in order to efficiently control multiple fungal diseases under field conditions in the soybean crop. These results show the feasibility of using induced resistance products as complements or even fullgood replacements to currently used chemical pesticides, fulfilling a role as important components of a more sustainable crop disease management system. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) were successfully prepared by γ-rays irradiation of solution containing 1.0–10 mM of silver nitrate and 1% chitosan. The optical characteristics and particles sizes of AuNPs were determined by UV-Vis spectra and TEM images, respectively. The size of AgNPs increased by the increase of silver concentration or the decrease of chitosan molecular weight in irradiated solution. The in vitro test showed that AgNPs inhibited the growth of Corynespora cassiicola on rubber-leaf extract media with the inhibitory efficiency of 52.1–100% by treatment of AgNPs with particle size from 15 to 5 nm, respectively. In addition, antifungal activity was found to reach ~100% by the addition of 90 ppm AgNPs. The in vivo foliar treatment of AgNPs on 9-month-old rubber plants showed that the treatment with 2.5–12.5 ppm AgNPs on tested plants after inoculation by spraying with C. cassiicola spores enhanced the rate of non-disease-infected plants from 6.0 to 93.3%, respectively, compared to the untreated control. The inhibition effect of AgNPs on fungal growth of C. cassiicola mycelial was also elucidated via SEM images. The AgNPs/chitosan synthesized by γ-irradiation is potentially promising to use as a fungicidal product for treating C. cassiicola, a serious pathogen fungus on rubber trees. [ABSTRACT FROM AUTHOR]

Energy metabolism is one of the key factors determining the growth and development of plants and the response to biotic and abiotic stresses. Sucrose non-fermentation 1 related protein kinase 1 (SnRK1) is an important energy-sensitive regulator that plays a key role in the overall control of carbohydrate metabolism. However, little is known about the function of SnRK1 in cucumber. In this study, metformin (an SnRK1 activator) and trehalose (an SnRK1 inhibitor) were used to investigate the role of SnRK1 signaling in cucumber. The results showed that SnRK1 activation could inhibit the growth of cucumber, slow down the net photosynthetic rate (Pn), reduce the contents of photosynthetic pigments and soluble sugars, and suppress the expression of genes related to sucrose metabolism. By contrast, SnRK1 inhibition yielded opposite results. Furthermore, SnRK1 activation and CsSnRK1 over-expression improved cucumber resistance to Corynespora cassiicola. While, SnRK1 inhibition and CsSnRK1 silencing reduced the resistance of cucumber to C. cassiicola. The results indicated that CsSnRK1 gene can positively regulate the resistance of cucumber to C. cassiicola. We conclude that CsSnRK1 signaling plays an important role in balancing the growth and immune response of cucumber. These results can be applied to the improvement of disease-resistant cucumber varieties. • CsSnRK1 signaling regulated cucumber growth. • SnRK1 activation and CsSnRK1 over-expression improved cucumber resistance to C. cassiicola. • SnRK1 inhibition and CsSnRK1 silencing reduced the resistance of cucumber to C. cassiicola. • CsSnRK1 signaling plays an important role in balancing the growth and immune response of cucumber. [ABSTRACT FROM AUTHOR]

Corynespora cassiicola attackes diverse agriculturally important plants, including soybean and cotton, in the US. It is a reemerge pathogen on cotton in southeastern US. Whole genome sequences of four cotton and one soybean isolate from Tennessee were used to develop single nucleotide polymorphism markers for cotton isolates. Cotton isolates had little diversity at the genome level and very little differentiation from the soybean isolate. Analysis of 75 isolates from cotton and soybean, using targeted-sequencing of 22 polymorphic SNP sites, revealed eight multi-locus genotypes and it appears a single clonal lineage predominates across the southeastern region. The cotton and soybean genome sequences were significantly different from the public reference genome derived from a rubber isolate and the utility of these novel resources will be discussed. [ABSTRACT FROM AUTHOR]

The fungus Corynespora cassiicola metabolises exogenous steroids in a unique and highly specific manner. Central to this, is the ability of this organism to functionalise substrates (androgens, progestogens) at the highly stereochemically hindered 8β-position of the steroid nucleus. A recent study has identified that 8β-hydroxylation occurs through inverted binding in a 9α-hydroxylase. In order to discern the metabolic fate of more symmetrical molecules, we have investigated the metabolism of a range of steroidal analogues functionalised with ring-D lactones, but differing in their functional group stereochemistry at carbon-3. Remarkably, the 3α-functionalised steroidal lactones underwent a mechanistically unique two step intramolecular cyclisation resulting in the generation of a ring-D spiro-carbolactone. This rapid rearrangement initiated with hydroxylation at carbon 14 followed by transesterification, resulting in ring contraction with formation of a butyrolactone at carbon-14. Remarkably this rearrangement was found to be highly dependent on the stereochemistry at carbon-3, with the β-analogues only undergoing 9α-hydroxylation. The implications of these findings and their mechanistic bases are discussed. [ABSTRACT FROM AUTHOR]