Oomycete Fungus Research Articles

Direct Isolation Method for Tomato-Infecting Phytophthora infestans

Infection of Phytophthora infestans at high altitudes in tropical regions causes symptoms of tomato late blight throughout the year. Even though it is very easy to find in the field, P. infestans is often very difficult to isolate aseptically in the laboratory. This study aims to evaluate direct isolation techniques that can increase the success of isolating P. infestans. Isolation was carried out on a non-specific medium, consisting of potato dextrose agar (PDA), corn meal agar (CMA), oatmeal agar (OMA), and water agar (WA) with three alternative types of antibiotics, i.e. chloramphenicol, amoxicillin, and rifampicin. Observations were carried out to determine the effect of the medium on sporangia induction and the age of the original colony’s growth in CMA and OMA media. The results showed that the isolation of P. infestans using the direct method was successfully carried out on non-specific PDA, CMA, OMA and WA medium. The highest isolation success rate was obtained on CMA medium with the addition of 50 mg L-1 rifampicin. The fastest sporangia induction (8 days) was shown by colonies grown on OMA medium with the addition of 50 mg L-1 rifampicin based on the category of abundant sporangia after 20 days of incubation. Rejuvenation of P. infestans colonies for research purposes in the laboratory is recommended to be carried out routinely twice a month. This research provides practical guidance for understanding the bioecology of P. infestans infecting tomato plants, especially for further study on oomycetes fungi.

Multigene phylogeny and haplotype analysis reveals predominance of oomycetous fungus, Phytophthora meadii (McRae) associated with fruit rot disease of arecanut in India

An oomycetous fungus Phytophthora causing fruit rot is the most devastating disease of arecanut in different agro-climatic zones of Karnataka with varied climatic profiles. The main aim of this investigation was to characterize the geo-distant Phytophthora populations infecting arecanut using robust morphological, multi-gene phylogeny and haplotype analysis. A total of 48 geo-distant fruit rot infected samples were collected during the South-West monsoon of 2017–19. Pure culture of the suspected pathogen was isolated from the infected nuts and pathogenic ability was confirmed and characterized. Colony morphology revealed typical whitish mycelium with stellate or petalloid pattern and appearance with torulose hyphae. Sporangia were caducous, semipapillate or papillate, globose, ellipsoid or ovoid-obpyriform in shape and sporangiophores were irregularly branched or simple sympodial in nature. Subsequent multi-gene phylogeny (ITS, β-tub, TEF-1α and Cox-II) and sequence analysis confirmed the identity of oomycete as Phytophthora meadii which is predominant across the regions studied. We identified 49 haplotypes representing the higher haplotype diversity with varying relative haplotype frequency. Comprehensive study confirmed the existence of substantial variability among geo-distant populations (n = 48) of P. meadii. The knowledge on population dynamics of the pathogen causing fruit rot of arecanut generated from this investigation would aid in developing appropriate disease management strategies to curtail its further occurrence and spread in arecanut ecosystem.

Assessment of the eco-toxicological effects in zoxamide polluted soil amended with fertilizers-An indoor evaluation

Zoxamide is a benzamide fungicide applied to control diseases caused by oomycete fungi. Fertilizers are important agricultural supplies to adjust soil properties and increase nutrition. To investigate the impact of zoxamide and seven fertilizers urea, phosphate fertilizer, potash fertilizer, compound fertilizer, organic fertilizer, vermicompost and soya bean cakes on the soil environment, the enantioselective dissipation characteristics of zoxamide, soil enzyme activities, pH and N, P nutrition changes were comprehensively analyzed in our present study. The enantioseparation method was successfully validated to quantify the zoxamide enantiomers in soil by HPLC using Chiral NQ (2)-RH column. Our results demonstrated that the R-(−)- and S-(+)-zoxamide half dissipated in the range of 10.88–17.81 and 8.05–14.41 days, respectively. S-(+)-zoxamide disappeared faster in soil. The vermicompost accelerated the dissipation rate of S-(+)-zoxamide, while urea, phosphate, organic and vermicompost fertilizer increased the dissipation selectivity. Zoxamide and fertilizers other than urea caused soil acidification during 80 days. Zoxamide was beneficial to soil catalase, instead inhibited soil urease, dehydrogenase activities and available phosphorus content. No significant effects on sucrase activity and available nitrogen content were found by zoxamide. Vermicompost and soya bean cakes had lasting and outstanding performance in efficiently improving soil enzyme activity and N, P nutrition. The comprehensive understanding of the ecological impact induced by chiral pesticide enantiomers and fertilizers on soil is vital to ensure the sustainable development and safety of agricultural production.

Quinazolinone Alkaloid Febrifugine and Its Analogues To Control Phytopathogenic Diseases Caused by Oomycete Fungi

AbstractControlling phytopathogenic diseases caused by oomycete fungi is still a challenge in crop protection research. Studies on identifying new starting points to control phytopathogens revealed that the quinazolinone alkaloids febrifugine (1) and halofuginone (2) are efficiently inhibiting the growth of Phytophthora infestans in microtiter tests. However, despite the very good in vitro activity of 0.13 and 0.06 ppm in IC50, respectively, both compounds did not exhibit a good control of P. infestans on tomato plants. Creating a homology model of prolyl‐tRNA synthetase – the molecular target of halofuginone – helped to understand the interactions between 2 and the binding pocket and guided the synthesis of further derivatives. Ultimately, we found that deoxy‐febrifugine (14) and halofuginol (17) and its derivatives were able to control P. infestans also on the plant.

Assessment of the Spatial Distribution and Risk Associated with Fruit Rot Disease in Areca catechu L.

Phytophthora meadii (McRae) is a hemibiotrophic oomycete fungus that infects tender nuts, growing buds, and crown regions, resulting in fruit, bud, and crown rot diseases in arecanut (Areca catechu L.), respectively. Among them, fruit rot disease (FRD) causes serious economic losses that are borne by the growers, making it the greatest yield-limiting factor in arecanut crops. FRD has been known to occur in traditional growing areas since 1910, particularly in Malnad and coastal tracts of Karnataka. Systemic surveys were conducted on the disease several decades ago. The design of appropriate management approaches to curtail the impacts of the disease requires information on the spatial distribution of the risks posed by the disease. In this study, we used exploratory survey data to determine areas that are most at risk. Point pattern (spatial autocorrelation and Ripley’s K function) analyses confirmed the existence of moderate clustering across sampling points and optimized hotspots of FRD were determined. Geospatial techniques such as inverse distance weighting (IDW), ordinary kriging (OK), and indicator kriging (IK) were performed to predict the percent severity rates at unsampled sites. IDW and OK generated identical maps, whereby the FRD severity rates were higher in areas adjacent to the Western Ghats and the seashore. Additionally, IK was used to identify both disease-prone and disease-free areas in Karnataka. After fitting the semivariograms with different models, the exponential model showed the best fit with the semivariogram. Using this model information, OK and IK maps were generated. The identified FRD risk areas in our study, which showed higher disease probability rates (>20%) exceeding the threshold level, need to be monitored with the utmost care to contain and reduce the further spread of the disease in Karnataka.

Antifungal potential of cinnamon essential oils against Phytophthora colocasiae causing taro leaf blight

BackgroundTaro leaf blight, caused by a severely destructive oomycete fungus Phytophthora colocasiae, is responsible for threatening yield loss worldwide. The pathogen has the ability to germinate and spread rapidly to other plants during favorable conditions resulting in acute decline and even death, causing 100% crop loss. Farmers usually rely on highly toxic systemic fungicides to control the disease, which is effective, but residual effects and resistance of these agrochemicals is still a concern. Recently as returning to nature people tend to use chemical-free products, especially edible stuff produced in organic agriculture. Therefore, the use of bio-pesticides and phytochemicals is gaining special attention by scientists as they are ecofriendly non-hazardous, sustainable, and potent alternatives to control many virulent plant pathogens The present research was conducted to assess the antifungal potential of cinnamon essential oils against P. colocasiae.Materials and methodsThe essential oils from cinnamon bark were extracted using microwave-assisted hydrodistillation equipment, and then their chemical constituents were evaluated using ATR FTIR spectroscopy. The antifungal potential of essential oil was assessed against mycelium, sporangia, zoospore, leaf necrosis, and corms lesions under laboratory conditions at, 0.156, 0.312, 0.625, 1.25, 2.5, 5.0 mg/mL concentrations. Hymexazol was used as positive control and no essential oil as negative control, while each treatment have three replications and experiment repeated twice.ResultsThe main component of oil was identified as cinnamaldehyde. The pathogen isolated from infected taro leaves was identified as P.colocasiae and then was used as a test fungus in the current study. Repeated experiments show maximum inhibition percentage of mycelial growth, zoospore germination, and sporulation of the fungus were observed at 0.625 mg/mL, whereas leaf necrosis was 100% inhibited at 1.25 mg/mL concentration.ConclusionThis research can be a reference for easy, cost-effective and environment-friendly management and control of taro leaf blight with phytochemicals and plant essential oil derivatives.Graphic abstract

Evaluation of different Brassica genotypes under field conditions against white rust disease (Albugo candida) of rapeseed-mustard for resistant sources

White rust or white blister disease caused by oomycete fungi, Albugo candia is one of the major devastating disease of rapeseed mustard. Continuous emergence of new races of the pathogen is responsible for breaking down of the resistance of already existing resistant cultivars. So there is need for the evaluation of existing resistant cultivars as well as new Brassica cultivars to find out stable resistance sources against the disease. In this context, 82 different Brassica genotypes, including 10 different Brassica species were evaluated in field, under natural conditions for the confirmation of resistance sources against Albugo candida in two successive years 2017-18 and 2018-19. Observations of percent disease severity and phenotypic disease reaction were taken at different time intervals of 70, 80 and 90 DAS. Infection rate and area under disease progress curve (AUDPC) were calculated for each genotype. Out of 82 Brassica genotypes evaluated, 26 were found free from the disease and 28 genotypes showed moderately resistant reaction while rest of the genotypes showed susceptible reaction at 90DAS. Minimum infection rate (0.0949) and AUDPC (69.44) was observed in DRMRJ 127 and SIVT-17-19 while maximum infection rate (0.1008) and AUDPC (588.0) was observed in 71 J0002 and RH 30, respectively at 90 DAS.

Assessing the toxicity of the benzamide fungicide zoxamide in zebrafish (Danio rerio): Towards an adverse outcome pathway for beta-tubulin inhibitors

Commercial benzamide fungicides are applied to crops to control damage caused by oomycete fungi and are used as veterinary pharmaceuticals in aquaculture. The mechanism of action of these fungicides is to induce mitotic arrest via binding to beta-tubulin, thus inhibiting tubulin polymerization. However, there are little toxicity data available for benzimidazole fungicides in fish. To address this knowledge gap, we conducted zebrafish embryo toxicity tests to assess deformities, survival, and sub-lethal responses following exposure to zoxamide (0, 0.5, 1.0, 2.5, 5.0 and 10 μM zoxamide). We hypothesized that skeletal deformities would be prevalent in zebrafish due to its mechanism of inhibiting beta-tubulin polymerization. Zoxamide was relatively toxic to zebrafish embryos and larvae, and survival was reduced ∼50 % at 2 days post fertilization (dpf) with 10 μM exposure and over time at 6 dpf, 2.5 μM exposure reduced survival by ∼20 %. Frequency of hatch was also reduced/delayed in zebrafish at 3 dpf with >2.5 μM zoxamide. Pericardial edema, body length shortening, and spine curvature were observed in larvae exposed to >5 μM. Mitochondrial bioenergetics were assessed in ∼30 hpf embryos (24-hour exposure) using an XFe24 Flux Analyzer and regression analysis revealed a negative relationship between basal respiration and zoxamide concentration. Superoxide dismutase 1 and caspase 3 mRNA levels were both decreased in 6 dpf larvae exposed to 2.5 μM zoxamide, but were not changed in expression at 0.5 nor 1 μM zoxamide. Continuous 6-day exposure to zoxamide reduced larval activity at 2.5 μM; conversely a 24-hour exposure (at 5–6 dpf) induced hyperactivity at 5 μM suggesting dose and time dependent effects on fish behavior. Based on sub-lethal endpoints, we conceptualize an adverse outcome pathway for chemicals that inhibit tubulin polymerization.

Insight Into Function and Subcellular Localization of Plasmopara viticola Putative RxLR Effectors.

Grapevine downy mildew, caused by oomycete fungus Plasmopara viticola, is one of the most devastating diseases of grapes across the major production regions of the world. Although many putative effector molecules have been identified from this pathogen, the functions of the majority of these are still unknown. In this study, we analyzed the potential function of 26 P. viticola effectors from the highly virulent strain YL. Using transient expression in leaf cells of the tobacco Nicotiana benthamiana, we found that the majority of the effectors could suppress cell death triggered by BAX and INF1, while seven could induce cell death. The subcellular localization of effectors in N. benthamiana was consistent with their localization in cells of Vitis vinifera. Those effectors that localized to the nucleus (17/26) showed a variety of subnuclear localization. Ten of the effectors localized predominantly to the nucleolus, whereas the remaining seven localized to nucleoplasm. Interestingly, five of the effectors were strongly related in sequence and showed identical subcellular localization, but had different functions in N. benthamiana leaves and expression patterns in grapevine in response to P. viticola. This study highlights the potential functional diversity of P. viticola effectors.

Design, synthesis and antifungal activity of threoninamide carbamate derivatives via pharmacophore model

Thirty-six novel threoninamide carbamate derivatives were designed and synthesised using active fragment-based pharmacophore model. Antifungal activities of these compounds were tested against Oomycete fungi Phytophthora capsici in vitro and in vivo. Interestingly, compound I-1, I-2, I-3, I-6 and I-7 exhibited moderate control effect (>50%) against Pseudoperonospora cubensis in greenhouse at 6.25 μg/mL, which is better than that of control. Meanwhile most of these compounds exhibited significant inhibitory against P. capsici. The other nine fungi were also tested. More importantly, some compounds exhibited remarkably high activities against Sclerotinia sclerotiorum, P. piricola and R. solan in vitro with EC50 values of 3.74–9.76 μg/mL. It is possible that the model is reliabile and this method can be used to discover lead compounds for the development of fungicides.

A comparative transcriptome approach for identification of molecular changes in Aphanomyces invadans infected Channa striatus.

Snakehead murrel, Channa striatus is an economically important aquatic species in Asia and are widely cultured and captured because of its nutritious and medicinal values. Their growth is predominantly affected by epizootic ulcerative syndrome (EUS) which is primarily caused by an oomycete fungus, Aphanomyces invadans. However, the molecular mechanism of immune response in murrel against this infection is still not clear. In this study, transcriptome technique was used to understand the molecular changes involved in C. striatus during A. invadans infection. RNA from the control (CF) and infected fish (IF) groups were sequenced using Illumina Hi-seq sequencing technology. For control group, 28,952,608 clean reads were generated and de novo assembly was performed to produce 60,753 contigs. For fungus infected group, 25,470,920 clean reads were obtained and assembled to produce 58,654 contigs. Differential gene expression analysis revealed that a total of 146 genes were up-regulated and 486 genes were down regulated. Most of the differentially expressed genes were involved in innate immune mechanism such as pathogen recognition, signalling and antimicrobial mechanisms. Interestingly, few adaptive immune genes, especially immunoglobulins were also significantly up regulated during fungal infection. Also, the results were validated by qRT-PCR analysis. These results indicated the involvement of various immune genes involved in both innate and adaptive immune mechanism during fungal infection in C. striatus which provide new insights into murrel immune mechanisms against A. invadans.

Mass screening of Trichoderma spp. for their antagonism against some plant pathogenic oomycetes fungi

In vitro efficacy of twenty five Trichoderma isolates (twenty were TCMS series viz., TCMS 2, 4, 5, 12, 14a, 14b, 15, 16, 24, 32, 34, 36, 43, 60, 62, 64, 65, 72, 85 and 93, and five Th series; Th 1, 3, 14, 19 and 32) were ascertained for their antagonistic activity against few major plant pathogenic oomycetes namely, Phytophthora infestans, P. parasitica and Pythium aphenidermatum using dual culture technique. P. infestans was isolated from infected potato leaves and Pythium aphenidermatum from infected brinjal. P. parasitica culture was collected from Central Potato Research Institute (CPRI), Simla. The present study was conducted at Biological Control Laboratory, Department of Plant Pathology, G.B. Pant University of Agriculture and Technology, Pantnagar. All the 25 Trichodrma isolates were found significantly effective against the test pathogens. TCMS-36 and TCMS-72 were found highly effective against P. aphinidermatum with 59.57 per cent inhibition of radial growth of the fungus. Maximum reduction in mycelial growth of P. infestans was recorded with isolate TCMS-64 (60.40%) followed by TCMS-65 (59.41%), TCMS-34 (58.42%), TCMS-24, TCMS-43 and TCMS-93 with 57.43 per cent inhibition. While, maximum inhibition of P. parasitica was recorded with TCMS-4 (92.75%) followed by TCMS-36 (92.23%), TCMS-2 (91.71%), TCMS-14a (91.17%) and TCMS-32 (90.67%). The selected potential isolates may be applied to sustainable and eco-friendly management of many major crop diseases caused by the oomycetes and other fungi.

Gene Profiling in Late Blight Resistance in Potato Genotype SD20.

Late blight caused by the oomycete fungus Phytophthora infestans (Pi) is the most serious obstacle to potato (Solanum tuberosum) production in the world. A super race isolate, CN152, which was identified from Sichuan Province, China, could overcome nearly all known late blight resistance genes and caused serious damage in China. The potato genotype SD20 was verified to be highly resistant to CN152; however, the molecular regulation network underlying late blight resistance pathway remains unclear in SD20. Here, we performed a time-course experiment to systematically profile the late blight resistance response genes using RNA-sequencing in SD20. We identified 3354 differentially expressed genes (DEGs), which mainly encoded transcription factors and protein kinases, and also included four NBS-LRR genes. The late blight responsive genes showed time-point-specific induction/repression. Multi-signaling pathways of salicylic acid, jasmonic acid, and ethylene signaling pathways involved in resistance and defense against Pi in SD20. Gene Ontology and KEGG analyses indicated that the DEGs were significantly enriched in metabolic process, protein serine/threonine kinase activity, and biosynthesis of secondary metabolites. Forty-three DEGs were involved in immune response, of which 19 were enriched in hypersensitive response reaction, which could play an important role in broad-spectrum resistance to Pi infection. Experimental verification confirmed the induced expression of the responsive genes in the late blight resistance signaling pathway, such as WRKY, ERF, MAPK, and NBS-LRR family genes. Our results provided valuable information for understanding late blight resistance mechanism of potato.

Deciphering the Role of Bacillus subtilis var. amyloliquefaciens in the Management of Late Blight Pathogen of Potato, Phytophthora infestans

An oomycete fungus Phytophthora infestans (Mont.) de Bary, is an incitant of destructive late blight disease on potato, causes severe yield loss worldwide. A study was undertaken for the management of the diseases by using the antagonistic bacterium. Twenty-five isolates of antagonistic bacteria were collected from various parts of Tamil Nadu from rhizospheric soils of Solanaceous crops potato, tomato and Solanum nigrum. These isolates were tested in vitro for its efficacy against P. infestans along with the FZB 24 strain of Bacillus subtilis var. amyloliquefaciens of M/S. Novozymes South Asia Ltd. B. subtilis var. amyloliquefaciens (FZB 24) showed a maximum inhibition of 35.56% against P. infestans. Based on this initial screening, the FZB 24 was used for further investigation under glass house and field conditions for the late blight disease management in potato. The glasshouse studies revealed that the application of corn flour formulation of B. subtilis var. amyloliquefaciens (FZB 24) as foliar spray @ 0.2% at 7 days interval for six times had shown significant reduction of 49.7% late blight severity over control. In addition, the potato plants from the above treatment showed higher activity of defence related enzymes such as peroxidase, polyphenol oxidase and phenylalanine ammonia lyase, which lead to higher accumulation of total phenols in comparison to untreated control plants. Under field conditions, B. subtilis var. amyloliquefaciens (FZB 24) treated potato plots registered significantly less severity of late blight disease which recorded higher tuber yield of 15.5 t/ha as against 9.4 t/ha in control.

Detecting Aphanomyces Invadans in Pure Cultures and EUS-infected Fish Lesions by Applying PCR

Aphanomyces invadans is an oomycete fungus which causes Epizootic Ulcerative Syndrome (EUS) disease in wide range of fresh and brackish water fish worldwide imposing serious economic losses. A diagnostic procedure, based on a polymerase chain reaction method (PCR) was developed to detect infection of fish with the A.invadans. A set of primers (1APM 1F and 1APM 6R) was used to specifically amplify A. invadans DNA. The PCR amplifies a 400 bp amplicon. A protocol for the extraction of A. invadans DNA from infected fish tissue and pure fungal cultures was developed. The method was tested on seven EUS-susceptible fish species (snakehead, snakeskin gourami, moonlight gourami, koi carp, catfish, gold fish, climbing perch) and one EUS-resistant fish (tilapia), artificially infected with A. invadans and pure cultures of Aphanomyces spp., Saprolegnia spp., Achlya spp., and Allomyces sp. Detection of A. invadans was possible at the early stage of sampling, which was 24 hours post injection in both EUS-susceptible and resistant fish. Resistant fish was found to be PCR-negative after 6 days of inoculation but in susceptible fish PCR-positive results obtained even after day 28 or in dead fish. Therefore PCR may be a useful method for detection EUS infection in fish from early stage of disease onset.

Graphene-Au nanoparticle based electrochemical immunosensor for fish pathogen Aphanomyces invadans detection

ABSTRACTEpizootic ulcerative syndrome (EUS) that is primarily caused by an invasive oomycete fungus Aphanomyces invadans is a devastating fish disease. Rapid diagnosis of EUS is significantly important for the control and treatment of this highly invasive disease. In our study, a label-free immunosensor constructed with G-AuNPs/SAM-Ab-BSA/GCE was proposed for the determination of Aphanomyces invadans. The electrode was prepared by the immobilization of anti-mycelium antibodies on graphene-AuNPs nanocomposite-cysteamine monolayers modified GCE. The optimized parameters were as follows: 90 min as the immersion time of SAM modified electrode in the anti-mycelium solution, 0.20 µg/mL as the concentration of anti-mycelium solution and 10 min as the interaction time of immunoreaction. The immunosensors exhibited low limit detection of 309 ng/mL and good reproducibility.

Seasonal yeast compositions in Forcipomyia taiwana (Diptera: Ceratopogonidae)

Forcipomyia taiwana, a biting midge, is one of the most annoying blood-sucking pests in Taiwan. The larvae of Forcipomyia species feed primarily on algae, and the adults feed on nectar for nutrition. After mating with male adults, females bite humans and digest blood for the formation and development of their eggs. The bites often cause human itching, swelling, skin lesion and even fatal shock. Harassment from this biting pest has become a serious problem and has influenced the quality of outdoor recreational activities. Thus, it is necessary to understand the ecology of F. taiwana to develop an effective control strategy. This study showed the seasonal variation of yeast compositions in the interior of F. taiwana. Furthermore, we found that Aureobasidium spp. appeared the most during collection times and these yeasts are able to decompose the cellulose, a major component in the cell wall of algae and Oomycete fungi. These fungi infect a broad range of host and have adverse effect on fitness of the biting midges. Thus, Aureobasidium spp. play a crucial role in the defense system of F. taiwana against pathogens. The study provides useful information that could be used in the development of biocontrol strategy in the future.

Modeling Ethylene Bisdithiocarbamate Efficacy Potential in the Presence of a Zoospore Attractant

A common class of fungicides are the ethylene bisdithiocarbamates (EBDCs) which decompose into ethylene bis-isothiocyanate sulfide (EBIS). EBIS is the primary fungitoxic component which is effective on various life stages of oomycete fungi, including zoospores (primary infection agents of oomycete fungal diseases). It is hypothesized that increased fungicide effectiveness can occur if zoospores are attracted to the toxicant (site of fungicide deposition) through chemotaxis using zoospore attractants (ZAs). Several probe studies proved this hypothesis when a ZA was formulated with EBDC products. A highly effective zoospore attractant is isovaleraldehyde (IVA), but IVA is volatile and dissipates rapidly in the environment. Therefore, various precursors for IVA and EBIS were studied to characterize the transient production and decline of EBIS and IVA from precursor material. First-order kinetic material balances and a stochastic modeling tool are created to fully exploit the conditions when the overlap of EBIS and IVA is maximized. A metric is proposed (measure of the overlap of fungicide and ZA residue) as an indirect measure of the potential for preventative fungicide efficacy when ZAs are included within the formulation. Therefore, fungicide formulations containing a ZA can be designed through model deployment that considers the production and decline patterns of both the fungicide and ZA, and the daily environmental dew cycle responsible for achieving the maximum concentration overlap when zoospores are the most infectious (e.g., mobile in the presence of dew) for enhanced crop disease control. It is found that the poly-IVA produrg investigated provides the maximum overlap of EBIS and IVA residues for many different EBDC formulations investigated. This modeling approach, and the examples provided for EBIS and IVA material balances, can be expanded for different fungicides and ZAs allowing for cause/effect to be inferred from multiple interacting factors, and formulations can be designed for optimal release characteristics that maximize the overlap of fungitoxic material and zoospore attractant.

Experimental infection of Aphanomyces invadans and susceptibility in seven species of tropical fish.

Aim:Epizootic ulcerative syndrome (EUS) causes by aquatic oomycete fungus, Aphanomyces invadans is a dangerous fish disease of a wide range of fresh and brackish water, wild and farmed fish throughout the world. The objective of the present study was to determine the susceptibility of a number of tropical fish species to the EUS and compare the severity of infection between experimental groups.Materials and Methods:Snakehead, Channa striata (Bloch, 1793); snakeskin gourami, Trichopodus pectoralis (Regan, 1910); koi carp, Cyprinus carpio (Linnaeus, 1758); broadhead catfish, Clarias macrocephalus (Günther, 1864); goldfish, Carassius auratus (Linnaeus, 1758); climbing perch, Anabas testudineus (Bloch, 1792); and Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) were challenged by intramuscular injection using zoospores of Aphanomyces invadans (NJM9701). The infected fish skins and muscles were examined for EUS histopathological characteristics, and the results on the severity of lesions and mortality were analyzed using SPSS program.Results:All zoospore-injected fish were shown to be susceptible to the EUS infection except Nile tilapia. Although, the general histopathological pattern was similar in the zoospore-injected group, but there were some variation in granulomatous reaction, that is the presence or absence of giant cells, and time of mortality were detected. The result of statistical analysis showed that there was a significant difference between species, (c2=145.11 and p<0.01).Conclusion:Gourami, koi carp, and catfish were demonstrated to be highly susceptible while goldfish and climbing perch were found to be moderately susceptible to the EUS infection. These findings suggested that the cellular response of fish to mycotic infection and granulomatous reaction varied in different fish species, which could not be an indicator of susceptibility or resistant to the EUS itself, although it was shown that the granulation rate and the level of maturity or solidification (consolidation of granulomas) were higher in resistant fish.

Plant endophytic fungi as a source of paclitaxel

Summary Endophytic fungi were isolated from different parts of the plants Corylus avellana (Corylaceae) and Ocimum basilicum (Lamiaceae) and then identified to the genus level based on the morphology of the fungal culture and the characteristics of the spores. The fungicidal and antitumor activity of isolates and extracts obtained from them was determined. We found that a few isolates from Corylus avellana and Ocimum basilicum produced metabolites that inhibited the growth of Oomycetes fungi to a highly significant extent. In the potato disc bioassay only an extract from the isolate C-9 showed an inhibitory action in tumor development. Paclitaxel presence in extract from the isolate C-9 was confirmed using the thin layer chromatography method (TLC) and UV-VIS spectroscopic analysis. The above results indicated that the tested samples revealed an antitumor activity. The detection of paclitaxel in the isolate C-9 suggests that the antitumor activity resulted probably from the presence of this taxane in the tested material.