Non-pathogenic Fungi Research Articles

Underground communication – the new elements of signalling pathways of arbuscular mycorrhizal symbiosis

Abstract Mycorrhiza is a symbiotic relationship between living cells of the roots of higher plants and non-pathogenic fungi which inhabit soil and belong to Glomeromycota (endomycorrhizae) and Basidiomycota, Ascomycota (ectomycorrhizae). Although the phenomenon of mycorrhiza was discovered by a Polish botanist F.D. Kamieński already in 1881, various stages of establishing the symbiotic relationship between the partners are still not fully understood and explained. According to the current knowledge, the roots of host plants release strigolactones, which stimulate germination and branching of spores of arbuscular fungi. As a result, the fungi synthesize molecular signals, i.e. chitooligosaccharides (COs) and lipochitooligosaccharides (LCOS), called MycF factors. Thanks to the development of molecular biology techniques the probable cascade of events during the recognition of fungal MycF factor by the host-plant has been outlined. The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase 1 (HMGR1) and also its product, mevalonic acid (MVA), play an essential role in the biosynthesis of sterols and isoprenoids in a plant cell. The recent studies indicate that these compounds may also play a very important role during establishing of the symbiotic mycorrhizal relationship. It is believed that MVA detects and transmits MycF factor to a cell nucleus of a host-plant triggering numerous necessary mechanisms in the plant cell to activate next steps of the mycorrhizal symbiosis. The discovery of HMGR1 and MVA sheds new light on symbiotic nature of mycorrhiza. This paper is a review of the current knowledge on the signal exchange during symbiotic interactions between mycorrhizal fungi and host plants. 1. Introduction. 2. Symbiotic nature of arbuscular fungi. 3. Arbuscular mycorrhiza in early stages. 4. Exchange of signaling molecules during arbuscular mycorrhiza formation. 5. Mevalonic acid – secondary signaling molecule messengers in the arbuscular mycorrhiza. 6. Protein kinase CCaMK as a key element in the establishment of arbuscular mycorrhiza. 7. Summary

Collagenolytic enzymes produced by fungi: a systematic review.

Specific proteases capable of degrading native triple helical or denatured collagen have been required for many years and have a large spectrum of applications. There are few complete reports that fully uncover production, characterization and purification of fungi collagenases. In this review, authors searched through four scientific on line data bases using the following keywords (collagenolytic OR collagenase) AND (fungi OR fungus OR fungal) AND (production OR synthesis OR synthesize) AND (characterization). Scientific criteria were adopted in this review to classify found articles by score (from 0 to 10). After exclusion criteria, 21 articles were selected. None obtained the maximum of 10 points defined by the methodology, which indicates a deficiency in studies dealing simultaneously with production, characterization and purification of collagenase by fungi. Among microorganisms studied the non-pathogenic fungi Penicillium aurantiogriseum and Rhizoctonia solani stood out in volumetric and specific collagenase activity. The only article found that made sequencing of a true collagenase showed 100% homology with several metalloproteinases fungi. A clear gap in literature about collagenase production by fungi was verified, which prevents further development in the area and increases the need for further studies, particularly full characterization of fungal collagenases with high specificity to collagen.

In vitro CONFRONTATION OF Trichoderma spp. ISOLATES WITH PHYTOPATHOGENIC AND NON-PHYTOPATHOGENIC FUNGI

The aim of this study was the confrontation of Trichoderma spp. with pathogenic and non-pathogenic fungi. The Trichoderma spp. and filamentous fungi (Fusarium solani, Alternaria sp., Colletotrichum gloeosporioides, and Aspergillus niger) were transferred to potato-dextrose-agar (PDA). The confrontation was performed using Petri dishes inoculated with mycelial disks in opposite position (9 mm) of Trichoderma spp. and filamentous fungi. After inoculation the plates remained under 25 ° C regime to 12 hours light for a period of seven days. After this period was evaluated qualitatively according to the scale of Bell et al. (1982), which consists of the suitability scores for the area percentage of the culture medium under expression of antagonism. The isolate of C. gloeosporioides (jatropha) was isolated which had statistically slightly inhibited growth by Trichoderma spp., Unlike the isolated Alternaria sp. (parsley) was isolated micelial fungi suffered the most antagonism. Statistically the Trichoderma isolate derived from pineapple promoted the highest antagonistic activity against isolates of pathogenic fungi tested, being a candidate for use in biocontrol.

Quantitative structure–activity relationships of dihydrofolatereductase inhibitors

Pneumocystis carinii is a nonpathogenic fungus found in respiratory tract of healthy humans. It is a major cause of death in AIDS patients. P. carinii dihydrofolatereductase inhibitors such as trimetrexate are currently used to treat P. carinii pneumonia. These drugs have several adverse side effects and, therefore, there is a critical need for the identification of novel dihydrofolatereductase inhibitors. In this work, quantitative structure – activity relationship models were derived for 395 stucturally diverse P. carinii dihydrofolatereductase inhibitors. A wide variety of molecular descriptors belonging to various structural properties were calculated for each molecule. Both linear (multiple linear regression) and non-linear (generalized regression neural network) models were developed to link the calculated descriptors as independent variables to their reported biological activity as dependent variable. Different variable transformation was performed on the both dependent and independent variables to obtain better multiple linear regression models. At first glance, it seemed applying variable transformation on the dependent variable was necessary to improve quality of the quantitative structure–activity relationships models because it made the model more predictive. Upon further inspection, the results were not necessarily surprising. In the other words, back-transforming predictions did not give unbiased estimations of pIC50. At the final trial, generalized neural network was employed to develop predictive quantitative structure–activity relationships model.

Japanese traditional dietary fungus koji Aspergillus oryzae functions as a prebiotic for Blautia coccoides through glycosylceramide: Japanese dietary fungus koji is a new prebiotic.

Background The Japanese traditional cuisine, Washoku, considered to be responsible for increased longevity among the Japanese, comprises various foods fermented with the non-pathogenic fungus Aspergillus oryzae (koji). We have recently revealed that koji contains an abundant amount of glycosylceramide. Intestinal microbes have significant effect on health. However, the effects of koji glycosylceramide on intestinal microbes have not been studied.Materials and methodsGlycosylceramide was extracted and purified from koji. C57BL/6N mice were fed a diet containing 1 % purified koji glycosylceramide for 1 week. Nutritional parameters and faecal lipid constituents were analyzed. The intestinal microbial flora of mice on this diet was investigated.ResultsIngested koji glycosylceramide was neither digested by intestinal enzymes nor was it detected in the faeces, suggesting that koji glycosylceramide was digested by the intestinal microbial flora. Intestinal microbial flora that digested koji glycosylceramide had an increased ratio of Blautia coccoides. Stimulation of B. coccoides growth by pure koji glycosylceramide was confirmed in vitro.ConclusionsKoji functions as a prebiotic for B. coccoides through glycosylceramide. Since there are many reports of the effects of B. coccoides on health, an increase in intestinal B. coccoides by koji glycosylceramide might be the connection between Japanese cuisine, intestinal microbial flora, and longevity.

Evaluation of the degradation of acetaminophen by the filamentous fungus Scedosporium dehoogii using carbon-based modified electrodes.

The nonpathogenic filamentous fungus Scedosporium dehoogii was used for the first time to study the electrochemical biodegradation of acetaminophen (APAP). A carbon fiber microelectrode (CFME) modified by nickel tetrasulfonated phthalocyanine (p-NiTSPc) and a carbon paste electrode (CPE) modified with coffee husks (CH) were prepared to follow the kinetics of APAP biodegradation. The electrochemical response of APAP at both electrodes was studied by cyclic voltammetry and square wave voltammetry. p-NiTSPc-CFME was suitable to measure high concentrations of APAP, whereas CH-CPE gave rise to high current densities but was subject to the passivation phenomenon. p-NiTSPc-CFME was then successfully applied as a sensor to describe the kinetics of APAP biodegradation: this was found to be of first order with a kinetics constant of 0.11day(-1) (at 25°C) and a half-life of 6.30days. APAP biodegradation by the fungus did not lead to the formation of p-aminophenol (PAP) and hydroquinone (HQ) that are carcinogenic, mutagenic, and reprotoxic (CMR). Graphical Abstract The kinetics of APAP biodegradation, followed by a poly-nickel tetrasulfonated phtalocyanine modified carbon fiber microelectrode.

Mannose-binding lectin (MBL) is the main complement activator on Aspergillus fumigatus conidia under immunocompromised conditions

Abstract Aspergillus fumigatus is normally a non-pathogenic fungus, but in immunocompromised patients this fungus becomes highly pathogenic. Complement activation are thought to be of crucial importance for elimination of A. fumigatus. However, which of the three complement pathways that are important under immunocompromised conditions are only partly understood. Conidia from a clinical isolate of A. fumigatus were co-incubated with serum before complement activation products C4b, C3b and TCC were measured in flow cytometry. Besides normal (NHS) and complement deficient sera plus complement inhibitors, we used umbilical cord serum (UCS) to mimic a compromised immune defense reflected in the low immunoglobulin (Ig) levels. In NHS, the classical pathway was the dominant initiator with the alternative pathway providing a strong C3b amplification. Classical pathway is known to be initiated via C1q binding to Ig, whereas MBL and ficolin-2 from the lectin pathway bind the fungus directly. UCS conveyed low IgG and no IgM binding to the conidia, and we observed that complement activation on A. fumigatus in UCS was predominantly MBL dependent. UCS with low MBL had significantly lower C3b deposition than serum from NHS with low MBL. Moreover, a close positive correlation between MBL levels and C3b deposition in UCS (Spearman r = 0.79, p < 0.0001, n = 23) was observed. The significance of MBL was emphasized by decreased neutrophilic phagocytosis of conidia via MBL inhibition in C1q−/− serum. We conclude that MBL is the main complement activator and phagocytosis initiator of A. fumigatus conidia in individuals with low Ig levels. This suggests a crucial role for the lectin pathway in protection against infection of A. fumigatus in immunocompromised patients.

Glucosylceramide Administration as a Vaccination Strategy in Mouse Models of Cryptococcosis.

Cryptococcus neoformans is an opportunistic fungal pathogen and the causative agent of the disease cryptococcosis. Cryptococcosis is initiated as a pulmonary infection and in conditions of immune deficiency disseminates to the blood stream and central nervous system, resulting in life-threatening meningoencephalitis. A number of studies have focused on the development of a vaccine against Cryptococcus, primarily utilizing protein-conjugated components of the Cryptococcus polysaccharide capsule as antigen. However, there is currently no vaccine against Cryptococcus in the clinic. Previous studies have shown that the glycosphingolipid, glucosylceramide (GlcCer), is a virulence factor in C. neoformans and antibodies against this lipid inhibit fungal growth and cell division. In the present study, we have investigated the possibility of using GlcCer as a therapeutic agent against C. neoformans infections in mouse models of cryptococcosis. GlcCer purified from a non-pathogenic fungus, Candida utilis, was administered intraperitoneally, prior to infecting mice with a lethal dose of C. neoformans. GlcCer administration prevented the dissemination of C. neoformans from the lungs to the brain and led to 60% mouse survival. GlcCer administration did not cause hepatic injury and elicited an anti-GlcCer antibody response, which was observed independent of the route of administration and the strains of mouse. Taken together, our results suggest that fungal GlcCer can protect mice against lethal doses of C. neoformans infection and can provide a viable vaccination strategy against Cryptococcus.

Editorial: Control of Plant Pathogens by Biogenic Elicitors and Possible Mechanisms of Action.

Editorial: Control of Plant Pathogens by Biogenic Elicitors and Possible Mechanisms of Action.

Determining the Pathogenic Potential of Non-sporulating Molds Isolated from Cutaneous Specimens.

Although non-sporulating molds (NSM) are frequently isolated from patients and have been recognized as agents of pulmonary disease, their clinical significance in cutaneous specimens is relatively unknown. Therefore, this study aimed to identify NSM and to determine the keratinolytic activity of isolates from cutaneous sites. NSM isolates from clinical specimens such as skin, nail, and body fluids were identified based on their ribosomal DNA sequences. Of 17 NSM isolates (7 Ascomycota, 10 Basidiomycota), eleven were identified to species level while five were identified to the genus level. These include Schizophyllum commune, a known human pathogen, Phoma multirostrata, a plant pathogen, and Perenniporia tephropora, a saprophyte. To determine fungal pathogenicity, keratinolytic activity, a major virulence factor, was evaluated ex vivo using human nail samples by measuring dye release from keratin azure, for NSM along with pathogens (Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum canis and Fusarium spp.) and nonpathogenic (endophyte) fungi for comparison. This study showed that pathogenic fungi had the highest keratinolytic activity (7.13±0.552 keratinase units) while the nonpathogenic endophytes had the lowest activity (2.37±0.262 keratinase units). Keratinolytic activity of two Ascomycota NSM (Guignardia mangiferae and Hypoxylon sp.) and one Basidiomycota NSM (Fomitopsis cf. meliae) was equivalent to that of pathogenic fungi, while Xylaria feejeensis showed significantly higher activity (p<0.05) than nonpathogenic endophytes. These results indicate that the pathogenic ability of NSM is species dependent; clinical isolates, especially more frequently isolated species, may be involved in disease etiology.

Identification and characterization of haemofungin, a novel antifungal compound that inhibits the final step of haem biosynthesis.

During recent decades, the number of invasive fungal infections among immunosuppressed patients has increased significantly, whereas the number of effective systemic antifungal drugs remains low and unsatisfactory. The aim of this study was to characterize a novel antifungal compound, CW-8/haemofungin, which we previously identified in a screen for compounds affecting fungal cell wall integrity. The in vitro characteristics of haemofungin were investigated by MIC evaluation against a panel of pathogenic and non-pathogenic fungi, bacteria and mammalian cells in culture. Haemofungin mode-of-action studies were performed by screening an Aspergillus nidulans overexpression genomic library for resistance-conferring plasmids and biochemical validation of the target. In vivo efficacy was tested in the Galleria mellonella and Drosophila melanogaster insect models of infection. We demonstrate that haemofungin causes swelling and lysis of growing fungal cells. It inhibits the growth of pathogenic Aspergillus, Candida, Fusarium and Rhizopus isolates at micromolar concentrations, while only weakly affecting the growth of mammalian cell lines. Genetic and biochemical analyses in A. nidulans and Aspergillus fumigatus indicate that haemofungin primarily inhibits ferrochelatase (HemH), the last enzyme in the haem biosynthetic pathway. Haemofungin was non-toxic and significantly reduced mortality rates of G. mellonella and D. melanogaster infected with A. fumigatus and Rhizopus oryzae, respectively. Further development and in vivo validation of haemofungin is warranted.

Mycologic Endocrinology.

The interactions of fungi and chemical messenger molecules, hormones or pheromones, are addressed in this chapter. These interactions include mammalian fungal pathogens, also plant pathogens, or non-pathogenic fungi, which can result in functional responses in receptor- or non-receptor-mediated fashions. Endogenous ligands in the fungi have been demonstrated to be important for mating in a number of systems. Mammalian hormones have been demonstrated to have stimulatory or inhibitory effects on growth for organisms such as Candida albicans, Paracoccidioides brasiliensis, Saccharomyces cerevisiae, Rhizopus nigricans, Aspergillus fumigatus, Coccidioides, and dermatophytic fungi. A number of fungi have been shown to have specific binding proteins for corticosteroid, estrogen and progesterone that are stereo-specific and high affinity. In some instances, the interactions of a mammalian hormone with the organism, in vivo, affects pathogenesis. Genome expression profiles of C. albicans in the presence of estradiol or progesterone, and S. cerevisiae with progesterone, indicate major up-regulation of various drug resistance pumps, like CDR1, and CDR2, can affect antifungal susceptibility. Azole antifungal interactions occur with fungal hormone binding proteins. Azoles also can block mammalian steroidogenesis. The finding of interactions of mammalian hormones with fungi and subsequent functional responses by the fungi, suggest that hormonal interactions with fungal systems has been conserved throughout evolution and have an important role in fungal pathogenesis, as well as in the overall biology of the organisms.

Assessment of the Antifungal Activity of Non-pathogenic Potatoassociated Fungi toward Fusarium Species Causing Tuber Dry Rot Disease

Twenty isolates of potato-associated fungi belonging to genera Aspergillus, Penicillium, Colletotrichum, and Trichoderma and recovered from healthy potato organs (stems, roots, and tubers) were screened for their antifungal potential toward Fusarium sambucinum and F. solani the major agents of dry rot disease in Tunisia. Tested using the dual culture method, all the potato-associated isolates had significantly lowered pathogen growth, noted after 7 days of incubation at 25°C as compared to the untreated control, but with a variable range depending on isolates used and targeted Fusarium species. F. sambucinum and F. solani were inhibited by 23.4 to 71.5% and by 29.2 to 62.1%, respectively, depending on antagonistic treatments tested. The percentage of Fusarium spp. inhibition ranged from 30.1 to 47.2% using Aspergillus spp. and from 30.1 to 67.3% with Penicillium spp. compared to 40.1-50.6% and 40.8% achieved using Colletotrichum sp. and Trichoderma sp., respectively. Strong hyphal lysis, formation of mycelial cords and early production of chlamydospores are the most frequent stress responses exhibited by both pathogens during their in vitro interactions with the potato-associated fungi. Tested as tuber treatment prior to pathogen challenge using a mixed inoculum composed of F. sambucinum and F. solani, 13 isolates out of the 20 tested led to a significant decrease, by 26.9 to 54.8%, in the mean diameter of dry rot lesion, as compared to the inoculated and untreated control. All tuber treatments had significantly decreased mean rot penetration, in comparison to Fusarium spp.-inoculated and untreated control, which was lowered by more than 50% using 14 out of the 20 potato-associated isolates. Thus, the present study clearly demonstrated that fungal isolates, occurring ubiquitously within potato plants, may be promising candidates for Fusarium spp. biocontrol and may be other potato diseases.

Bio-suppression of Fusarium Wilt Disease in Potato Using Nonpathogenic Potato-associated Fungi

Ten nonpathogenic Aspergillus spp. and Penicillium spp. isolates, naturally occurring within healthy potato plants and previously selected based on their ability to suppress Fusarium dry rot disease, were evaluated for their in vitro antifungal potential against Fusarium sambucinum, F. oxysporum and F. graminearum and their effects against Fusarium wilt severity and on plant growth and production. Tested through the dual culture technique on PDA medium, all isolates tested had significantly decreased Fusarium spp. growth relative to the untreated control. Growth inhibition, achieved after 7 days of incubation at 25°C, varied from 32.3 to 42.9% using Aspergillus spp. and from 44.1 to 59.6% with Penicillium spp. The highest inhibition, by about 55-59%, was noted using isolates E.36.11 (P. chrysogenum) and E.39.11 (Penicillium sp.). Competition, mycoparasitism, hyphal lysis, early formation of resting structures and mycelial cords, and decreased sporulating ability are the main effects recorded during antagonism exerted toward targeted Fusarium species. Fusarium wilt severity, noted 75 days posy-planting, was significantly lowered by 29 to 47% on potato plants treated using 7 out the 10 isolates tested. The highest wilt severity decrease, by 41-47% over the inoculated and untreated control, was achieved using E.13.11 (A. niger), E.25.11 (A. flavus), E.36.11 (P. chrysogenum), and E.29.11 (P. polonicum) based treatments. Plant inoculated with Fusarium spp. and treated with E.29.11 (P. polonicum), E.13.11 (A. niger), E.41.11 (A. terreus), E.60.11 (A. flavus), and E.25.11 (A. flavus) showed 36-46% higher aerial part growth. The most interesting improvements of root and tuber fresh weights, achieved using the majority of isolates tested, ranged between 22-40% and 15-21%, respectively. Further investigations are needed to more elucidate the antifungal activity of the extracellular metabolites of the most effective isolates toward Fusarium species infecting potato.

Fungal endophytes: modifiers of plant disease.

Many recent studies have demonstrated that non-pathogenic fungi within plant microbiomes, i.e., endophytes ("endo"=within, "phyte"=plant), can significantly modify the expression of host plant disease. The rapid pace of advancement in endophyte ecology warrants a pause to synthesize our understanding of endophyte disease modification and to discuss future research directions. We reviewed recent literature on fungal endophyte disease modification, and here report on several emergent themes: (1) Fungal endophyte effects on plant disease span the full spectrum from pathogen antagonism to pathogen facilitation, with pathogen antagonism most commonly reported. (2) Agricultural plant pathosystems are the focus of research on endophyte disease modification. (3) A taxonomically diverse group of fungal endophytes can influence plant disease severity. And (4) Fungal endophyte effects on plant disease severity are context-dependent. Our review highlights the importance of fungal endophytes for plant disease across a broad range of plant pathosystems, yet simultaneously reveals that complexity within plant microbiomes presents a significant challenge to disentangling the biotic environmental factors affecting plant disease severity. Manipulative studies integrating eco-evolutionary approaches with emerging molecular tools will be poised to elucidate the functional importance of endophytes in natural plant pathosystems that are fundamental to biodiversity and conservation.

Common foliar fungi of Populus trichocarpa modify Melampsora rust disease severity.

Nonpathogenic foliar fungi (i.e. endophytes and epiphytes) can modify plant disease severity in controlled experiments. However, experiments have not been combined with ecological studies in wild plant pathosystems to determine whether disease-modifying fungi are common enough to be ecologically important. We used culture-based methods and DNA sequencing to characterize the abundance and distribution of foliar fungi of Populus trichocarpa in wild populations across its native range (Pacific Northwest, USA). We conducted complementary, manipulative experiments to test how foliar fungi commonly isolated from those populations influence the severity of Melampsora leaf rust disease. Finally, we examined correlative relationships between the abundance of disease-modifying foliar fungi and disease severity in wild trees. A taxonomically and geographically diverse group of common foliar fungi significantly modified disease severity in experiments, either increasing or decreasing disease severity. Spatial patterns in the abundance of some of these foliar fungi were significantly correlated (in predicted directions) with disease severity in wild trees. Our study reveals that disease modification is an ecological function shared by common foliar fungal symbionts of P.trichocarpa. This finding raises new questions about plant disease ecology and plant biodiversity, and has applied potential for disease management.

Initiation of phospholipomannan β-1,2 mannosylation involves Bmts with redundant activity, influences its cell wall location and regulates β-glucans homeostasis but is dispensable for Candida albicans systemic infection.

Pathogenic and non-pathogenic fungi synthesize glycosphingolipids, which have a crucial role in growth and viability. Glycosphingolipids also contribute to fungal-associated pathogenesis. The opportunistic yeast pathogen Candida albicans synthesizes phospholipomannan (PLM), which is a glycosphingolipid of the mannosylinositol phosphorylceramide family. Through its lipid and glycan moieties, PLM contributes to the initial recognition of the yeast, causing immune system disorder and persistent fungal disease through activation of host signaling pathways. The lipid moiety of PLM activates the deregulation signaling pathway involved in yeast phagocytosis whereas its glycan moiety, composed of β-1,2 mannosides (β-Mans), participates to inflammatory processes through a mechanism involving Galectin-3. Biosynthesis of PLM β-Mans involves two β-1,2 mannosyltransferases (Bmts) that initiate (Bmt5) and elongate (Bmt6) the glycan chains. After generation of double bmtsΔ mutants, we show that Bmt5 has redundant activity with Bmt2, which can replace Bmt5 in bmt5Δ mutant. We also report that PLM is located in the inner layer of the yeast cell wall. PLM seems to be not essential for systemic infection of the yeast. However, defect of PLM β-mannosylation increases resistance of C.albicans to inhibitors of β-glucans and chitin synthesis, highlighting a role of PLM in cell wall homeostasis.

An Endophyte Constructs Fungicide-Containing Extracellular Barriers for Its Host Plant

Surface cracks create sites for pathogen invasion. Yew trees (Taxus) hyperbranch from long-lived buds that lie underneath the bark [1], resulting in persistent bark cracking and deep air pockets, potentially allowing pathogens to enter the nutrient-rich vascular system (vertical phloem and inter-connected radial medullary rays [MR]). Yew is famous as the source of the anti-cancer diterpenoid drug Taxol. A mystery has been why both the tree and its resident non-pathogenic fungi (endophytes) synthesize Taxol, apparently redundantly [2-7]. These endophytes, as well as pure Taxol, suppress fungal pathogens including wood-decaying fungi (WDF) [8-11]. Here we show that a Taxol-producing fungal endophyte, Paraconiothyrium SSM001 [12], migrates to pathogen entry points including branch cracks. The fungus sequesters Taxol in intracellular hydrophobic bodies that are induced by WDF for release by exocytosis, after which the bodies can coalesce to form remarkable extracellular barriers, laced with the fungicide. We propose that microbial construction of fungicide-releasing hydrophobic barriers might be a novel plant defense mechanism. We further propose that the endophyte might be evolutionarily analogous to animal immune cells, in that it might expand plant immunity by acting as an autonomous, anti-pathogen sentinel that monitors the vascular system.

Impact of cover crop in pre-plant of apple orchards: relationship between crop health, root inhabiting fungi and rhizospheric bacteria

Manici, L. M., Kelderer, M., Caputo, F., Nicoletti, F., De Luca Picione, F. and Topp A. R. 2015. Impact of cover crop in pre-plant of apple orchards: relationship between crop health, root inhabiting fungi and rhizospheric bacteria. Can. J. Plant Sci. 95: 947–958. Replant disease of fruit tree orchards has a multifactorial etiology, mainly due to the decline in soil biodiversity along with an increase in root rot pathogens, which can be principally countered with appropriate cropping practices. Therefore, a study on the impact of cover crops on plant health of young fruit trees in long-term orchards was performed. Bioassays were performed over two consecutive growing cycles using soil from a multigeneration apple orchard affected by replant disease. First, a cycle was performed with three cover crops (alfalfa, barley, marigold) and apple rootstock plantlets; at the end, the above-ground part of the plant was removed and root residues left in the soil. In the second cycle, an apple orchard planting was simulated upon the first experimental design. Changes of diversity and composition of root inhabiting fungi and rhizospheric bacteria were evaluated as well as apple plant growth response to the pre-plant treatments. Results suggest that one cycle with alternate plants was sufficient to induce changes at the rhizosphere level, despite soil microbial resilience caused by the same long-term soil management. Rhizospheric bacteria were generally affected by plant genotype. Findings suggest that all three different cover crops can harbor almost all fungal species that colonize apple in replanted orchards (Fusarium spp., Pythum spp., binucleate Rhizoctonia sp., Cylindrocarpon-like-fungi and a several nonpathogenic saprophytic fungi named “other”), but their infection frequency varied according to the host plant. A single pre-plant break treatment did not overall differ significantly in plant growth of subsequent apple tree; however, break with marigold, which increased abundance of nonpathogenic root inhabiting fungi more than other cover crops, gave significantly higher plant growth than obtained after barley. This study provides evidence about cover-crop potential to increase soil diversity in long-term permanent cropping systems and to manipulate root colonizing fungi involved in crop health.

Sorption ability of the composite sorbent for water treatment from radioactive elements

The goal of research is to develop the composite sorbent with application of various metal oxides nanoforms and nonpathogenic mold fungi mycelium modified by these nanoforms. This article describes the producing method of the composite sorbent and the research results of the sorbent sorption ability while the sorption process conditions are changed.