Fungal Infestation Research Articles

​Effect of Modified Atmosphere Storage Conditions on Seed Quality and Longevity of Kabuli Chickpea Varieties

Background: Chickpea is an important pulse crop. The area, production and productivity of Kabuli chickpea are very low as compared to Desi type chickpea. While, worldwide chickpea production is predominated by Desi type (80%) compared to Kabuli type (20%). One of constraints limiting the Kabuli chickpea seed production is the fast seed deterioration process as, they possesses thin and fragile seed coat which makes it more susceptible to infestation of pulse beetle and storage fungi. In addition, the day by day increase in usage of chemical pesticides and increase in health awareness among the people and demand towards organic based products necessitate a new alternative method of seed storage than the routinely used storage methods. Modified atmosphere storage is an alternative method to avoid chemical fumigants, which are said to cause residual effect on seed material and development of resistance by storage pest against insecticides. Methods: The present investigation on modified atmosphere packaging (MAP) was carried out at the Department of Processing and Food Engineering, College of Agricultural Engineering, University of Agricultural Sciences, Raichur during March 2017. Further, its storage and seed quality assessment were conducted at Seed Quality and Research Laboratory of National Seed Project (Crops), Seed Unit, University of Agricultural Sciences, Dharwad during March 2017 to May 2018. Result: The results revealed that the Kabuli chickpea seeds stored in the gaseous atmosphere with the combination of CO2 (80%) + N2 (20%) + O2 (0%) [C2] have maintained the maximum germination (92%) followed by Vaccum Packaging [C5] by using 700 gauge polyethylene bag for 14 months under ambient conditions above the Indian Minimum Seed Certification Standards.

Chemically characterized nanoencapsulated Homalomena aromatica Schott. essential oil as green preservative against fungal and aflatoxin B1 contamination of stored spices based on in vitro and in situ efficacy and favorable safety profile on mice.

Present study deals with the efficacy of nanoencapsulated Homalomena aromatica essential oil (HAEO) as a potent green preservative against toxigenic Aspergillus flavus strain (AF-LHP-NS 7), storage fungi, AFB1, and free radical-mediated deterioration of stored spices. GC-MS analysis revealed linalool (68.51%) as the major component of HAEO. HAEO was encapsulated into chitosan nanomatrix (CS-HAEO-Ne) and characterized through SEM, FTIR, and XRD. CS-HAEO-Ne completely inhibited A. flavus growth and AFB1 biosynthesis at 1.25 μL/mL and 1.0 μL/mL, respectively in comparison to unencapsulated HAEO (1.75 μL/mL and 1.25 μL/mL, respectively). CS-HAEO-Ne caused significant reduction in ergosterol content in treated A. flavus and provoked leakage of cellular ions (Ca+2, Mg+2, and K+) as well as 260 nm and 280 nm absorbing materials. Depletion of methylglyoxal level in treated A. flavus cells illustrated the novel antiaflatoxigenic efficacy of CS-HAEO-Ne. CS-HAEO-Ne exhibited superior antioxidant efficacy (IC50 (DPPH) = 4.5 μL/mL) over unencapsulated HAEO (IC50 (DPPH) = 15.9 μL/mL) and phenolic content. CS-HAEO-Ne depicted excellent in situ efficacy by inhibiting fungal infestation, AFB1 contamination, lipid peroxidation, and mineral loss with acceptable sensorial profile. Moreover, broad safety paradigm (LD50 value = 7150.11 mg/kg) of CS-HAEO-Ne also suggests its application as novel green preservative to enhance shelf life of stored spices.

Fabrication, physico-chemical characterization, and bioactivity evaluation of chitosan-linalool composite nano-matrix as innovative controlled release delivery system for food preservation

The aim of the present study was to encapsulate linalool into chitosan nanocomposite (Nm-linalool) for developing novel controlled release delivery system in order to protect stored rice against fungal infestation, aflatoxin B1 (AFB1) contamination, and lipid peroxidation. The chitosan-linalool nanocomposite showed spherical shapes, smooth surface with monomodal distribution as revealed by SEM and AFM investigation. FTIR and XRD represented peak shifting and changes in degree of crystallinity after incorporation of linalool into chitosan nanocomposite. Nanoencapsulation of linalool showed higher zeta potential and lowered polydispersity index. TGA analysis reflected the stability of Nm-linalool with reduced weight loss at varying temperatures. Biphasic pattern, with initial rapid release followed by sustained release illustrated controlled delivery of linalool from chitosan nanocomposite, a prerequisite for shelf-life enhancement of stored food products. Chitosan nanocomposite incorporating linalool displayed prominent antifungal and antiaflatoxigenic activity during in vitro as well as in situ investigation in rice with improved antioxidant potentiality. Further, Nm-linalool displayed considerable reduction of lipid peroxidation in rice without exerting any adverse impact on organoleptic attributes. In conclusion, the investigation strengthens the application of chitosan-linalool nanocomposite as an innovative controlled nano-delivery system for its practical application as novel environmentally friendly eco-smart preservative in food and agricultural industries.

Mycotoxins: Food Safety, Consumer Health and Africa’s Food Security

Mycotoxins are among the major food contaminants, especially in Africa and in many developing countries. Contamination by mycotoxins has greater consequences in terms of both human and animal health as well as economics of these countries. This phenomenon may impact negatively Africa’s food availability and food security scenarios. This review evaluated mycotoxins in foods, safety of foods, consumer health and Africa’s food security. This review also gave comprehensive information on socio-economic implications of mycotoxins of foods and the effects on food security in Africa. In Africa, information concerning food contamination by mycotoxins is very scanty and the problem of storing agricultural produce under poor storage conditions that may predispose food to fungal infestation and subsequent mycotoxin contamination are common in African countries. Consumption of moldy produce or food contaminated with mycotoxins and the dangers of mycotoxicoses as well as the impact on public health necessitated a comprehensive approach to reduce the impact on public health and consumer safety. The challenges of food shortages, wars and conflicts, poor governance and planning in African countries have increased the problems of mycotoxins in Africa. In order to improve food safety, consumer health and availability of needed food by the teeming African population, education and enlightenment of Africans on the economic and health implications of mycotoxins are very crucial. The major techniques for control and mitigation of mycotoxins need to be explained to consumers. A robust regulatory control and effective analyses and detection of mycotoxins as well as good produce handling and storage are important to stem the tides of effects of mycotoxins in foods in Africa countries to improve consumer health and food security.

Assessing the Levisticum officinale Koch. essential oil as a novel preservative for stored chia seeds (Salvia hispanica L.) with emphasis on probable mechanism of action.

The present study was undertaken to explore the inhibitory effect of Levisticum officinale Koch. essential oil (LoffEO) on the growth and aflatoxin B1 secretion by Aspergillus flavus (AF-LHP-SH1, aflatoxigenic strain) causing deterioration of stored chia seeds (Salvia hispanica). The chemical profile analysis of LoffEO by GC-MS analysis revealed the presence of α-terpinyl acetate (26.03 %) as a major component followed by terpineol <1- > (24.03 %) and citronellal (24.03 %). Results on antifungal and antiaflatoxigenic activity indicated that LoffEO at 2.0 and 1.75 μL/mL caused complete inhibition of growth and aflatoxin B1 production, respectively. Antifungal toxicity of LoffEO was strongly correlated with the inhibition of ergosterol content, leakage of cellular ions, and disintegration of membrane permeability. Reduction in cellular methylglyoxal by LoffEO indicated a novel antiaflatoxigenic mechanism of action. The LoffEO showed moderate free radical quenching activity in DPPH assay (IC50 = 26.10 μL/mL) and exhibited remarkable inhibitory efficacy against lipid peroxidation of chia seeds. In addition, LoffEO presented strong in situ antiaflatoxigenic efficacy, and exhibited non-phytotoxic nature, acceptable sensory characteristics, and favorable safety profile (LD50 = 19786.59 μL/kg), which recommends its practical utilization as a novel and safe preservative to improve the shelf life of stored chia seeds from fungal infestation and aflatoxin B1 contamination.

Reproductive development and genetic structure of the mycoheterotrophic orchid Pogoniopsis schenckii Cogn.

BackgroundPogoniopsis schenckii Cogn. is a mycoheterotrophic orchid that can be used as a model to understand the influence of mycoheterotrophy at different stages of the reproductive cycle. We aimed to verify the presence of endophytic and epiphytic fungi at each stage of the reproductive process and investigated how the breeding system may relate to genetic structure and diversity of populations. In this study we performed anatomical and ultrastructural analyses of the reproductive organs, field tests to confirm the breeding system, and molecular analysis to assess genetic diversity and structure of populations.ResultsDuring the development of the pollen grain, embryo sac and embryogenesis, no fungal infestation was observed. The presence of endophytic fungal hyphae was observed just within floral stems and indehiscent fruit. Beyond assuring the presence of fungus that promote seed germination, specific fungi hyphae in the fruit may affect other process, such as fruit ripening. As other mycoheterotrophic orchids, P. schenckii is autogamous, which may explain the low genetic diversity and high genetic structure in populations.ConclusionsWe discuss an interesting interaction: fungal hyphae in the indehiscent fruit. These fungal hyphae seem to play different roles inside fruit tissues, such as acting in the fruit maturation process and increasing the proximity between fungi and plant seeds even before dispersion occurs. As other mycoheterotrophic orchids, P. schenckii is autogamous, which may explain the low genetic diversity and high genetic structure in populations. Altogether, our findings provide important novel information about the mechanisms shaping ecology and evolution of fragmented populations of mycoheterotrophic plant.

ПОСІВНІ ЯКОСТІ НАСІННЯ ЕХІНАЦЕЇ ПУРПУРОВОЇ (ECHINACEA PURPUREA (L.) MOENCH.)

The energy of germination and laboratory germination of Echinacea purpurea seeds have been studied, as it is the sowing qualities of seeds that are the basis for successful reproduction of the species in culture. Peculiarities of germination of culture seeds depending on harvest terms are studied. It is noted that the seeds of 2017-2018 are not conditioned and are not recommended for cultivation in medicinal crops in order to obtain quality medicinal raw materials according to generally accepted standards, while the seeds of 2020 harvest have a fairly high quality and belong to the basic category. The article also presents data on the effect of disinfection with ethyl alcohol on the sowing qualities of Echinacea purpurea seeds, the tendency to increase germination energy and germination in the variant with treated seeds. Seeds, endowed with a high rate of laboratory germination, belongs to the category of original and is recommended for further propagation. Such seeds may have good field germination, although this figure will be slightly lower in any case, because the laboratory for growing seeds creates optimal conditions, which is not always possible in the field. This is usually associated with the influence of biotic and abiotic factors: temperature, humidity, light, conditions and timing of sowing, soil fertility, its infestation by pests and pathogens, and so on. In the course of studies of germination energy and laboratory germination, attention was paid to the degree of damage to the seeds of Echinacea purpurea by mold fungi. On average, when determining the energy of germination, the degree of damage by molds was weak, but when determining laboratory germination, a large degree of damage to achenes by molds was additionally manifested. When comparing the degree of fungal infestation of treated and non-disinfected seeds, we noted a low degree of infestation (for disinfected achenes) and a medium degree of infestation (for non-disinfected seeds). When determining the germination energy of disinfected echinacea seeds, the signs of purple lesions were generally invisible.

Disturbance by invasive pathogenic fungus alters arthropod predator-prey food-webs in ash plantations.

According to the disturbance-succession theory, natural disturbances support biodiversity and are expected to increase the complexity of food-webs in forest ecosystems by opening canopies and creating a heterogeneous environment. However, a limited number of studies have investigated the impact of disturbance by invasive pathogenic species and succession on arthropod predator-prey food-webs in forest ecosystems. Hymenoscyphus fraxineus is a pathogenic fungus of ash trees that is invasive in Europe and causes massive dieback, mainly of the common ash Fraxinus excelsior across its native range. Here we investigated how this pathogenic fungus affects food-webs of web-building spiders and their prey in understorey vegetation of ash plantations. In 23 young and middle-aged ash plantations that were distributed along a gradient of infestation by H. fraxineus (29%-86% infestation), we measured the vegetation structure (canopy openness, shrub coverage, herb/grass coverage), the trait composition of local spider communities (web type, body size), the prey availability and the prey intercepted by spider webs. We then evaluated the multivariate prey composition (prey type, body size) and network properties. Hymenoscyphus fraxineus opened the ash tree canopy, which resulted in denser shrub coverage. The dense shrub vegetation changed the composition of web types in local spider communities and increasing fungus infestation resulted in reduced mean body size of spiders. Infestation by H. fraxineus reduced the availability of predaceous Coleoptera and increased the availability of herbivorous Coleoptera as potential prey. The mean body size of captured prey and the per capita capture rates of most prey groups decreased with increasing fungus infestation. Hymenoscyphus fraxineus infestation indirectly reduced the complexity in bipartite networks and the trophic functional complementarity in local web-building spider communities. The plantation age affected the vegetation structure but did not affect the studied food-webs. Forest disturbance by the invasive pathogen affected four trophic levels (plant-herbivore-coleopteran intermediate predator-top predator web-building spiders) and, contrary to the disturbance-succession theory, disturbance by the fungus simplified the web-building spider-prey food-webs. The results support the view that H. fraxineus represents a threat to the biodiversity and ecosystem functioning in the simplified ecosystems of ash plantations.

Breeding Resistance for Post Flowering Stalk rot (Macrophomina phaseolina) in Maize Identification of Resistance against Post Flowering Stalk Rot (Macrophomina phaseolina) in Maize

Maize is one of the most important staple food crops in the World. However, the yields of maize have been affected by various fungal infestations. Post flowering stalk rot is one of the devastating diseases and so, we planned our study to order to identify suitable resistance maize genotypes against post flowering stalk rot (PFSR) complex caused by Macrophomina phaseolina through in-vivo screening and toothpick method for creating artificial epiphytotics. A total of 20 maize inbreds were screened and crossed in Line × Tester mating design (15 × 5) during Kharif 2019, Six resistant inbred lines were identified and generated the 75 F1s (SCHs) at MRC, ARI, Rajendranagar, Hyderabad. All these 20 parents and 75 F1s along with three checks were evaluated by raising the crop in disease sick plot accompanied by toothpick inoculation during Rabi, 2019-20, in a Randomized Block Design with two replications. The field screening of maize genotypes by the standard toothpick method which needs about 40 days for expression of plant drying symptoms due to PFSR and data are possible to record only at the time of crop harvesting using 1-9 rating scale of PFSR for scoring disease severity in-vivo condition by splitting the stem of each plant. As a result, most of the genotypes were exhibited disease reaction varying from resistant (score 2) to moderately resistant (score 5) against M. phaseolina. While studying the genetics of PFSR, we found that interaction of lines and testers were proportionally contributed towards resistant, and degree of dominance is preferably non-additive gene action, it shows that the magnitude of dominance was higher than additive effect indicating that PFSR resistance is largely governed by dominance effect i.e., non additive component is not fixable for resistance. It is also found that the resistant genotypes also exhibited highest significant positive heterosis and combining ability effects (GCA and SCA). A considerable yield reduction in grain yield (10.5 to 28.3%) over checks was observed in susceptible lines. Most of the genotypes were found resistant as the reduction in yield is low. Hybrids developed using such lines exhibited high yields which are promoted for extensive testing to know their stability before release as commercial hybrids.

Assessment of Seed-Borne Plant Pathogenic Fungi, Insect Emergence and Percentage Germinability Associated with Harvested and Stored Rice in Kwara State, Nigeria

This study was conducted to assess the incidence of seed-borne fungi, insect emergence as it affect the germinability rate of rice seed collected from the major rice growing areas of Kwara State, Nigeria, The rice seeds were collected during the dry season of 2019. Five (5) fungi species were isolated from all the rice samples. The incidence of fungi pathogens vary from one locality to another, as well as the frequency of occurrence. The pathogens isolated include Fusarium. oxysporium, Aspergillus spp., Aspergillus flavus, Aspergillus fumigatus., Cladosporium sp., Mucor sp. FARO 44 rice variety has the highest incidence of fungal pathogen(12.5× 104) while local varieties Alhaji Sule and Kuddo has the lowest incidence of (0.5× 104) respectively. Penicillium sp. has the highest percentage frequency of occurrence (49.3%) while cladosporium sp has lowest (1.33%) across all samples. Sample 9(F-52), 15(E) and 17(K) has the lowest percentage germinability of 41, 40 and 45% while sample 11(AB) and 8(K) has the highest percentage germinability of 84% and 77% respectively. All the samples do not have the most serious damaging insect infestation of Sitophilus oryzae but some of the sample has infestation of some other insects such as Rhyzopertha dominca, a lesser grain borer and a primary stored pest of cereals, Tribolium. castaneum a secondary pest and some other unidentified insects in varying percentage. Measures such as lowest moisture content of seed meant for storage and proper cleaning of the store must be put in place to avoid seed deterioration as a result of seed borne fungal pathogen and insect infestation.

An overview of skin disorders in under-fives over a ten-year period in a tertiary institution in South: South, Nigeria

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Skin disorders can be a significant cause of distress to both children and their care-givers. The scope of prevalent skin disorders differ from one country to the other. Therefore an insight into the occurrence, patterns and distribution of skin disorders in a target group will be beneficial to inform care and provide support that is relevant to that target population. The aim of this study is to determine the skin problems prevalent amongst children that are five years and below managed at the University of Port Harcourt Teaching Hospital, Alakahia, Nigeria.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods: &lt;/strong&gt;This was a retrospective cross sectional study of children five years and below that visited the dermatology outpatient clinic at the University of Port Harcourt Teaching Hospital, Alakahia between the period of January 2006 and December 2015.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; There was equal ratio of male to female patients with slight female preponderance. The eleven most common lesions were papular urticaria, atopic dermatitis, scabies, warts, vitiligo, molluscum contagiosum, tinea corporis, impetigo, seborrhoeic dermatitis, pityriasis rosea and tinea capitis.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;Skin disorders are common among children under five years. Allergic skin disorders, bacterial, viral and fungal skin infections, skin infestation (scabies) and pigmentary disorders (vitiligo) are major skin manifestations in this study.&lt;/p&gt;

Fungal Infection Exacerbate Nasal Polyposis: A study conducted at KGN Teaching Hospital Bannu-KPK.

Background: Nasal polyps were believed to be small tumours of nasal or sinus mucosa. With progressing research, they are associated with enlargement or swelling of nasal or sinus mucosa, allergy, asthma, any infection, sensitivity to aspirin, and/or cystic fibrosis unclear etiology. The present study aims to evaluate the prevalence of fungal infections that can result in the onset of nasal polyposis in the residents of district Bannu, Pakistan.&#x0D; Methodology: A cross-sectional study was conducted at the ENT Department of Khalifa Gul Nawaz (KGN) teaching hospital in Bannu from March 2018 to February 2020, including 180 polyposis patients with the presence or absence of any fungal infestation. The subjects possessing mass other than nasal polyp based on clinical diagnosis were excluded from the study. The fungal infestation was observed with nasal endoscopy, and the patients were hospitalized for functional endoscopic sinus surgery (FESS). The staging of the nasal polyposis was based on the CT scan findings. The condition was classified into three grades, i.e., grade I, II and III. The data was statistically analysed on SPSS version 20.0.&#x0D; Results: Out of 180 patients diagnosed clinically for nasal polyposis, 97(53.88%) were males. The fungal infestation was positive in 73(41%) specimens. Around 52.72% of patients were found with bilateral involvement. Of which, 31.57% were diagnosed with an allergic event. The fungus Aspergillus was observed in 40.55% of specimens. The one-year follow-up displayed an overall recurrence rate of 40%, i.e., 38(52.05%) patients from the fungal group and 34(47.22%) from the non-fungal group.&#x0D; Conclusion: It is concluded from the study outcomes that the incidence of nasal polyposis with or without fungal infection is associated with the environment and the discrete host response. Moreover, individuals living with lower socioeconomic conditions in crowded and humid areas tend to suffer more.

About the significance of the fungal genus Alternaria for the food sector: plant pathogens and mycotoxins

The fungal infestation of agricultural crops worldwide leads to considerable economic losses every year. Moreover, certain major plant pathogens like Alternaria species produce harmful secondary metabolites, so-called mycotoxins, which may result in food contamination and therefore a potential health risk for consumers. Data on the occurrence and the toxicological potential of the “emerging” Alternaria toxins are still scarce, which limits comprehensive risk assessments. Here, we present a summary of current Alternaria research focusing on the development of innovative analytical tools to determine contamination patterns in various food products and the investigations of metabolic defense strategies in plants and mammals (biotransformation). By the application of sophisticated LC-MS-based multi-toxin quantitation methods, barely studied toxins and even biologically modified toxins were revealed to contribute considerable concentrations to the overall exposure. Furthermore, in vivo studies gave intriguing first insights in bioavailability, metabolism, and excretion rates of Alternaria toxins in rats. These valuable data set demonstrates the necessity for further studies to approach the question, whether legal regulations of Alternaria toxins would be appropriate to continuously ensure and increase food safety.

Gamma irradiation and drying method: The effects on kola nut powder

Kola nut is a fruit produced by the kola tree which is mostly found in West Africa. Kola nut contains a high amount of caffeine and it is used as a flavoring agent in many drinks. At storage, kola nut may become mold-infested resulting in rotting and rendering it unusable. However, well-dried kola nut coupled with gamma (ƴ) irradiation treatment can prevent fungi infestation at storage. This study sought to determine the effects of ƴ-irradiation and drying method on proximate, phytochemical, and free scavenging properties of kola nuts. The kola nuts were dried in shade and solar tent. The milled samples packaged in polyethylene bags were irradiated with cobalt-60 source at 2 kGy/h dose rate, and the delivered dose determined with ethanolchlorobenzene dosimeter. The ƴ-irradiated and un-irradiated flours were quantitatively analyzed to determine proximate, phytochemical, and free radical scavenging activities. The fat, ash, protein, carbohydrate, and caffeine contents were slightly altered by the ƴ-irradiation, while moisture content remained stable. Total phenolic content in the aqueous extract of the irradiated kola nut increased at irradiation dose above 5 kGy. The changed in total flavonoid content was inconsistent with increasing irradiation dose while 2,2-diphenyl-1-picrylhydrazyl decreased at irradiation dose higher than 5 kGy. Importantly, the health and nutritional qualities of kola nut were not sufficiently affected by ƴ-irradiation. The kola nut type, irradiation dose, and drying method, and the respective interactions differed in effects with respect to proximate, phytochemical and free scavenging properties of kola nuts. Generally, the observed irradiation-induced impacts were not deleterious on the studied properties of kola nut.

Characterising corn grain using infrared imaging and spectroscopic techniques: a review

Corn is the largest cultivated grain crop in the world and the need to characterize corn grains based on various quality parameters is becoming essential as the demand for corn is increasing continuously in various end product applications. The conventional methods like visual inspection and analytical techniques involves sample destruction and are either subjective or time-consuming resulting in a growing requirement for the development of non-destructive techniques for a rapid and accurate determination of corn grain constituents and contaminants. This paper reviews the potential of infrared (IR) based imaging and spectroscopic techniques to determine quality parameters of corn grains, and their opportunities to incorporate in the supply chain of corn-based agro-industries. The variety and hardness of corn grains could be efficiently identified through the near infrared (NIR) hyperspectral imaging with accuracies ranging from 80 to 95% and 60 to 85%, respectively. IR imaging techniques determined the oil content of corn grains with standard error ranging between 0.7 and 1.3%. The detection of fungal infestations and mycotoxins in corn grains were widely studied using NIR, short-wave infrared (SWIR) and fluorescence hyperspectral imaging techniques with accuracies ranging from 75 to 98% and 70 to 97%, respectively. These techniques showed a better accuracy for infestations and variety classification (85–90%) and kernel hardness (60–65%) when used in the reflectance operational mode and proved effective for both single and bulk kernel analysis.

Diversity of experimental designs for the fabrication of antifungal surfaces for the built environment.

The fungal infestation in construction industries is a major problem with a very high removal cost that needs to be controlled not only to prevent the fouling of surfaces but also to prevent allergic reactions or respiratory problems especially in immunocompromised individuals. To combat fungal invasion, several experimental approaches to produce antifungal surfaces have been developed. Here, we reviewed the current strategies in designing antifungal surfaces and classified those approaches into two major categories: the chemical and/or physical modification of the actual material surface and nanoparticle-based coating formulations created using the functionalised nanoparticles. KEY POINTS: • Antifungal effect of micro- and nano-structured superhydrophobic surfaces. • Long-term antifungal effect conferred through biocides. • Advanced coatings based on functionalised silica, TiO2 and ZnO nanoparticles.

More diverse tree communities promote foliar fungal pathogen diversity, but decrease infestation rates per tree species, in a subtropical biodiversity experiment

Abstract Fungal pathogens have the potential to affect plant biogeography and ecosystem processes through their influence on the fitness and functioning of their plant hosts. Simultaneously, changes in plant communities can influence fungal pathogen communities. Exactly which host plant attributes determine the composition of fungal pathogen communities on the leaves remains poorly understood. Here, we characterized foliar fungal pathogen communities in subtropical tree communities along an experimental diversity gradient in Jiangxi, South‐East China. On 32 tree species, we identified all visible fungal structures and symptoms microscopically and studied fungi‐specific traits such as conidia or spores in detail. We asked how different facets of biodiversity, including taxonomic, phylogenetic and functional tree diversity, shape fungal diversity and fungal infestation at different scales. We found a positive relationship between tree richness and fungal richness at the plot level. At the level of individual trees of the same species, the relationship between tree species richness and fungal species richness was marginally significantly negative. Importantly, the fungal infestation rates decreased as tree species richness increased, suggesting that colonization of hosts by specialist fungi was impeded by dilution of the pool of available hosts. Moreover, we found evidence for similar topologies between phylogenetic topologies of trees and fungal genera which is a precondition for coevolution and we identified leaf traits, including leaf habit (deciduous/evergreen), leaf magnesium content and stomata size that predicted fungal richness and infestation. Synthesis. Our study indicates that host tree species harbour different foliar fungal pathogens, which sums up to the highest fungal pathogen richness in more diverse forest stands. At the same time, the foliar fungal pathogen infestation rate for each tree species decreased with increasing tree richness in forests. We identified leaf traits that can help to better predict fungal pathogen richness and infestation, and we show that phylogenetically closely related tree species harbour phylogenetically closely related foliar fungal pathogens. These new insights might be helpful to improve the pest resilience of future forests and plantations.

Local Tree Diversity Suppresses Foliar Fungal Infestation and Decreases Morphological But Not Molecular Richness in a Young Subtropical Forest.

Leaf fungal pathogens alter their host species’ performance and, thus, changes in fungal species composition can translate into effects at the tree community scale. Conversely, the functional diversity of tree species in a host tree’s local neighbourhood can affect the host’s foliar fungal infestation. Therefore, understanding the factors that affect fungal infestations is important to advance our understanding of biodiversity-ecosystem functioning (BEF) relationships. Here we make use of the largest BEF tree experiment worldwide, the BEF-China experiment, where we selected tree host species with different neighbour species. Identifying fungal taxa by microscopy and by high-throughput DNA sequencing techniques based on the internal transcribed spacer (ITS) rDNA region, we analysed the fungal richness and infestation rates of our target trees as a function of local species richness. Based on the visual microscopic assessment, we found that a higher tree diversity reduced fungal richness and host-specific fungal infestation in the host’s local neighbourhood, while molecular fungal richness was unaffected. This diversity effect was mainly explained by the decrease in host proportion. Thus, the dilution of host species in the local neighbourhood was the primary mechanism in reducing the fungal disease severity. Overall, our study suggests that diverse forests will suffer less from foliar fungal diseases compared to those with lower diversity.

Screening Methods for Isolation of Biocontrol Epiphytic Yeasts against Penicillium digitatum in Lemons.

Worldwide, the green rot caused by Penicillium digitatum is one of the most aggressive postharvest diseases of lemons. Searching for sustainable alternatives to chemical fungicides, epiphytic yeasts as potential biocontrol agents were isolated from citrus fruits using a tailor-made selective medium. For disclosing their antagonistic potential against P. digitatum, obtained isolates were subjected to direct screening methods, both in vitro and in vivo. In the course of the primary in vitro screening that comprised dual culture assays, 43 yeast strains displaying antagonistic activities against the pathogen were selected. Subsequently, such strains were subjected to an in vivo screening that consisted of a microscale test, allowing the selection of six yeast strains for further analysis. In the final screening using macroscale in vivo tests, three strains (AcL2, AgL21, and AgL2) displaying the highest efficiencies to control P. digitatum were identified. The protection efficiencies in lemons were 80 (AcL2), 76.7 (AgL21), and 75% (AgL2). Based on sequence analysis of the PCR amplified D1/D2 domains of the 26S rRNA genes, they were identified as representatives of the species Clavispora lusitaniae. Interestingly, the strains exhibited a broad action spectrum among citrus fruits as they were also able to combat the green mold disease in grapefruit and two orange varieties. The direct screening methods applied in this study favored the recovery of efficient candidates for application as biological control agents to combat fungal infestations of citrus fruits.

An overview of fish disease and parasite occurrence in the cage culture of Oreochromis niloticus: A case study in Lake Victoria, Kenya

Abstract Cage aquaculture has been on a steady rise in Lake Victoria, Kenya, since 2016, resulting in the current culturing of over 3,600 cages of Tilapia (O. niloticus) (Orina et al., 2018). Unfortunately, there has been limited, if any, focus on fish health aspects. Rise in intensification and commercialization predisposes fish stocks to disease due to rise in stress levels and consequent reduction in the fish immunity. Nutrient rich surroundings create a conducive environment for rapid proliferation of bacterial and saprophytic fungal growth leading to net clogging and consequently a low biological oxygen demand. Such conditions predispose the stocks to infections. This study was conducted to provide a baseline analysis of the health conditions/status of the cultured fish in this region. It encompassed studies from 2016 to 2018 on tilapia of the genus O. niloticus using both experimental (using standard procedures and protocols) and socio-economic studies (using structured questionnaires, see annexure 1). Results found the following occurrences; bacterial infections (10%), fungal infestations (12.5%), myxosporean parasites in the gills (5%), parasitic copepods (10%) and fin rot (2.5%) in the stocks. There were no significant differences between abiotic parameters in the cage locations and the wild (p &amp;gt; 0.05). Additionally, 90% of the respondents had no fish disease training or clue on the treatment action necessary whenever fish diseases struck. Findings from this study put to the fore the significance of fish diseases in a cage culture system in light of commercialization of the industry and the importance of biosecurity and maintenance of optimal environmental conditions within the scope of Blue Economy growth in this region. This study did not detect any disease or parasite of zoonotic importance.