Search

Anthracnose disease caused by Colletotrichum lindemuthianum (Sacc. and Magnus) Lams- -Scrib is one of the most devastating seed-borne diseases of common bean (Phaseolus vulgaris L.). In the present study, we evaluated the antifungal activity of Bunium persicum essential oil (EO) and its main constituents on mycelial growth, sporulation and spore germination inhibition of C. lindemuthianum. The main objective of this study was to investigate the effect of EO and its main constituents on decreasing the activity of cell wall degrading enzymes (CWDEs) produced by C. lindemuthianum, which are associated with disease progress. Also, the effects of seed treatment and foliar application of EO and its main constituent, cuminaldehyde, on anthracnose disease severity was investigated. The essential oil of B. persicum, was obtained by using a clevenger apparatus and its major constituents were identified by gas chromatography-mass spectrometry (GC-MS). The EO was characterized by the presence of major compounds such as cuminaldehyde (37.7%), γ-terpinene (17.1%) and β-pinene (15.4%), which indicated antifungal effects against C. lindemuthianum. This pathogen did not grow in the presence of EO, cuminaldehyde and γ-terpinene, β-pinene at 1,500; 1,010 and 1,835 ppm concentrations, respectively. Also, sporulation and spore germination of C. lindemuthianum was completely inhibited by EO and cuminaldehyde. Synergistic effects of the main constituents showed that combing γ-terpinene with cuminaldehyde induced a synergistic activity against C. lindemuthianum and in combination with β-pinene caused an additive effect. Activities of pectinase, cellulase and xylanase, as main CWDEs, were decreased by EO and its main constituents at low concentration without affecting mycelial growth. Seed treatment and foliar application of peppermint EO and/or cuminaldehyde significantly reduced the development of bean anthracnose. We introduced B. persicum EO and constituents, cuminaldehyde and γ-terpinene, as possible control agents for bean anthracnose.

Drawbacks associated with the use of chemical fungicides to control plant pathogenic fungi such as Botrytis cinerea stimulate the need for alternatives. Therefore, the present study was carried out to determine the antifungal potentials of Moringa oleifera extracts against B. cinerea. Phytochemical analysis using qualitative chemical tests revealed the presence of huge amount of crucial phytochemicals compounds like phenolic compounds, alkaloids and saponins in the M. oleifera leaf extract. Antifungal bioassay of the crude extracts indicated better mycelial growth inhibition by methanol leaf extract (99%). The minimum inhibitory concentration (MIC) was 5 mg/ml with 100% spore germination inhibition and minimum fungicidal concentration (MFC) was 10 mg/ml with 98.10% mycelial growth inhibition using broth micro dilution and poisoned food techniques. Gas chromatography–mass spectrometry (GC-MS) analysis led to the identification of 67 volatile chemical compounds in the leaf extract with 6-decenoic acid (Z)- (19.87%) was the predominant compound. Further chemical elucidation of the crude extracts performed by liquid chromatography with tandem mass spectrometry (LC-MS/MS) showed the presence of non-volatile chemical compounds, mostly flavones, flavonoids and phenolic acids (i.e. quercetin and kaempferol). Scanning electron microscopy and transmission electron microscopy analysis showed positive effect of M. oleifera leaf extract on the treated conidia and mycelium of B. cinerea. Findings revealed that irreversible surface and ultra-structural changes with severe detrimental effects on conidia and mycelium morphology compared to control treatment. Overall findings suggested that M. oleifera leaf extract is a promising candidate for biological control of fungal pathogens, thus limiting overdependence on chemical fungicides. Resumo As desvantagens associadas ao uso de fungicidas químicos para controlar fungos fitopatogênicos, como Botrytis cinerea, estimulam a necessidade de alternativas. Portanto, o presente estudo foi realizado para determinar o potencial antifúngico de extratos de Moringa oleifera contra B. cinerea. A análise fitoquímica usando testes químicos qualitativos revelou a presença de uma grande quantidade de compostos fitoquímicos cruciais, como compostos fenólicos, alcaloides e saponinas no extrato da folha de M. oleifera. O bioensaio antifúngico dos extratos brutos indicou melhor inibição do crescimento micelial pelo extrato de folhas de metanol (99%). A concentração inibitória mínima (MIC) foi de 5 mg/mL com 100% de inibição da germinação de esporos e a concentração fungicida mínima (MFC) foi de 10 mg/mL com 98,10% de inibição do crescimento micelial usando microdiluição em caldo e técnicas de alimentos envenenados. A análise por cromatografia gasosa-espectrometria de massa (GC-MS) levou à identificação de 67 compostos químicos voláteis no extrato da folha, sendo o ácido 6-decenoico (Z) (19,87%) o composto predominante. Elucidação química adicional dos extratos brutos realizada por cromatografia líquida com espectrometria de massa em tandem (LC-MS/MS) mostrou a presença de compostos químicos não voláteis, principalmente flavonas, flavonoides e ácidos fenólicos (ou seja, quercetina e kaempferol). As análises de microscopia eletrônica de varredura e microscopia eletrônica de transmissão mostraram efeito positivo do extrato de folhas de M. oleifera sobre os conídios e micélios tratados de B. cinerea. Os resultados revelaram a superfície irreversível e alterações ultraestruturais com graves efeitos prejudiciais sobre os conídios e a morfologia micelial, em comparação com o tratamento de controle. Os resultados gerais sugeriram que o extrato da folha de M. oleifera é um candidato promissor para o controle biológico de patógenos fúngicos, limitando assim a dependência excessiva de fungicidas químicos.

The dynamic interactions of plants and arbuscular mycorrhizal fungi (AMF) that facilitate the efficient uptake of minerals from soil and provide protection from various environmental stresses (biotic and abiotic) are now also attributed to a third component of the symbiosis. These are the less investigated mycorrhizae helper bacteria (MHB), which constitute a dense, active bacterial community, tightly associated with AMF, and involved in the development and functioning of AMF. Although AMF spores are known to host several bacteria in their spore walls and cytoplasm, their role in promoting the ecological fitness and establishment of AMF symbiosis by influencing spore germination, mycelial growth, root colonization, metabolic diversity, and biocontrol of soil borne diseases is now being deciphered. MHB also promote the functioning of arbuscular mycorrhizal symbiosis by triggering various plant growth factors, leading to better availability of nutrients in the soil and uptake by plants. In order to develop strategies to promote mycorrhization by AMF, and particularly to stimulate the ability to utilize phosphorus from the soil, there is a need to decipher crucial metabolic signalling pathways of MHB and elucidate their functional significance as mycorrhiza helper bacteria. MHB, also referred to as AMF bioenhancers, also improve agronomic efficiency and formulations using AMF along with enriched population of MHB are a promising option. This review covers the aspects related to the specificity and mechanisms of action of MHB, which positively impact the formation and functioning of AMF in mycorrhizal symbiosis, and the need to advocate MHB as AMF bioenhancers towards their inclusion in integrated nutrient management practices in sustainable agriculture.

Coastal shores near the industrial park of Quintero Bay in central Chile exhibit increasing concentrations of copper (Cu) and polycyclic aromatic hydrocarbons (PAHs), well above international standards. This raises concern about their combined toxic effects on early development stages of kelps. Accordingly, we aimed to assess more accurately the independent and combined effects of Cu and PAHs on gametogenesis and sporophyte development in the kelp Lessonia spicata from central Chile by in vitro cultivation. Independent Cu and PAH trials were performed using increasing nominal concentrations of Cu and PAHs in the ranges 0.8–200 µg L−1 and 0.05–100 µg L−1, respectively. Cu and PAH median effective concentrations (EC50) on gametogenesis and early sporophyte formation were calculated using DRC in the R environment. Then, combined EC50 Cu + PAH trials were conducted to determine their effects on gametogenesis and sporophyte formation. Cu EC50 values on gametogenesis and sporophyte formation were up to three orders of magnitude lower than EC50 reported previously on spore germination in kelps. The gametogenesis (EC50 = 1.39 µg L−1) was more sensitive to Cu than sporophyte formation (EC50 = 11 µg L−1). Inversely, sporophyte formation (EC50 = 0.04 µg L−1) was more sensitive to PAHs (EC50 = 0.11 µg L−1). Considering the entire exposure period, the combined EC50 Cu + PAH exposure was the most harmful and rapid for L. spicata microscopic stages, especially the synergistic effect on early sporophytes. This highlights the need to acquire an integrated knowledge of the seasonal variation of pollutants and their combination on highly intervened coasts.

Some fern species are among the world’s worst weeds, but little is known about the establishment of alien ferns in relatively conserved ecosystems. Exotic species may outperform native ones during germination and facilitate invasion into new environments. Macrothelypteris torresiana is an Asian fern species that was introduced and spread throughout multiple areas of tropical America. We tested the hypothesis that germination of the exotic fern will be higher at high resource levels and will have wider ecological amplitude compared to native fern species in a cloud forest in central Mexico. Spore germination was evaluated through a gradient of water potential (0 to − 1.0 MPa), photon flux density (0 to 200 µmol m−2 s−1), and light quality (0 to 7.2 red:far-red ratio) in the laboratory, whereas plant relative frequency was determinate in the forest to describe the distribution of the ferns under the light environment. Comparing to three native ferns (sun-loving Hypolepis blepharochlaena and shade-loving Blechnum wardiae and Polystichum ordinatum), M. torresiana was more tolerant to water deficit, germinated better under low photon flux but responded similarly to light quality gradient, and occurred over a far wider range of field light conditions. Our results support the hypothesis that the germination requirements of the invasive fern species are less specific and thus facilitate the colonization of sites with diverse light conditions and water availability.

Fusarium species are generally appropriated pathogens in roots, plant debris and soil causing major disease as primary, secondary invader and co-invader with other pathogens. Fusarium chlamydosporu...

Late blight, caused by the oomycete Phytophthora infestans, is economically the most important foliar disease of potato. To assess the importance of the leaf surface, as the site of the first encounter of pathogen and host, we performed untargeted profiling by liquid chromatography-mass spectrometry of leaf surface metabolites of the susceptible cultivated potato Solanum tuberosum and the resistant wild potato species Solanum bulbocastanum. Hydroxycinnamic acid amides, typical phytoalexins of potato, were abundant on the surface of S. tuberosum, but not on S. bulbocastanum. One of the metabolites accumulating on the surface of the wild potato was identified as lysophosphatidylcholine carrying heptadecenoic acid, LPC17:1. In vitro assays revealed that both spore germination and mycelial growth of P. infestans were efficiently inhibited by LPC17:1, suggesting that leaf surface metabolites from wild potato species could contribute to early defense responses against P. infestans.

Few pteridophytes have proven the capacity to accumulate and remediate heavy metals from contaminated soils. Pityrogramma calomelanos, a non-seasonal fast-growing, a cosmopolitan fern, is a good in...

Drynaria bonii H. Christ is a medicinal plant that has traditionally been used for the treatment of chronic diseases and tuberculosis. However, D. bonii has not yet been cultivated or propagated. In this study, we optimized the conditions for the spore culture of D. bonii to produce sporophytes. First, we evaluated the effects of various factors, such as temperature, light intensity, potting material, and pH, on spore germination and early gametophyte development. Under optimal culture conditions, 95–99% of the spores germinated within 2 weeks of culture. Next, based on these results, we established a culture system for gametophyte development and sporophyte production. Mature gametophytes first appeared 5 months post-germination (mpg), and at 12 mpg, the rate of production of heart-shaped gametophytes reached 56.6%. Sporophytes at the early first-leaf stage first appeared at 6 mpg, and at 12 mpg, the rate of formation of sporophytes reached 15.4%. Interestingly, 6.3% of all gametophytes produced multiple sporophytes. Additionally, 42–62% of the gametophytes also produced multiple secondary gametophytes, indicating a high potential of D. bonii gametophytes to generate new gametophytes and, subsequently, sporophytes. When transferred to new trays or pots, sporophytes grew well and showed 100% survival. Overall, we conclude that this spore culture system can be successfully used for the propagation of D. bonii sporophytes.

Common gardens are experimental plantations for comparing the performance of tree species while eliminating many of the variables that prevail in natural tree stands. The aim of this study was to evaluate the biodiversity of corticolous lichens on Danish tree species (Acer pseudoplatanus, Alnus glutinosa, Betula pendula, Fagus sylvatica, Fraxinus excelsior, Quercus robur and Tilia cordata) under common garden conditions and to examine the height distribution of particular lichen species. Observations were recorded through regular sampling of at least 36 lichen species on the main stems (from the base of the stem to the treetops) of 44-year-old trees at four common garden sites. Acer pseudoplatanus and Fraxinus excelsior had the greatest lichen species richness and Shannon diversity values while these measures were significantly lower for Betula pendula and Fagus sylvatica. The distribution of lichen species appeared biased among tree species. The general lichen distribution and relative sample height were weakly related (nonmetric multidimensional scaling). However, single lichen species showed a clear differential distribution along the tree stem (P Lepraria incana, Pseudosagedia aenea and Arthonia atra were mainly found at the stem base while Lecanora carpinea, L. chlarotera, Lecidella elaeochroma, Physcia tenella and Xanthoria parietina, were most abundant at around 70% of the total tree height. The differential distribution of single lichen species presumably reflects different specific requirements during spore germination and thallus growth. By isolating the unique effect of key variables (tree species and height), this study contributes to the knowledge base of corticolous lichen ecology.

The aim of this study was to demonstrate for the first time Fuligo septica spore viability in the stratosphere through spore germination and its complete life cycle. These protozoan spores were flo...

Interest in ferns as objects of biotechnological research is determined by the characteristics of their development and reproduction, which is important for understanding the evolutionary pathways of seed plants. The previous published data on the phytohormones involvement in the regulation of fern gametophytes ontogenesis during in vitro cultivation are analyzed and summarized. The possibility of fern reproduction through spores application as explants using in vitro methods is considered. The effects of exogenous treatment with cytokinins, auxins, gibberellins, ethylene, jasmonic acid, and brassinosteroids on spore germination, gametophyte morphology and development are analyzed. The roles of gibberellins and antheridiogen in the formation of fern gametophytes’ sexual dimorphism are discussed. Data on disturbances of the sexual process in ferns and the phytohormones’ involvement in the formation of apogamic sporophytes are summarized.

Melatonin, a ubiquitous molecule found in almost all organisms, is considered an important regulator in plant growth. However, little is known about the interactive effect of melatonin and arbuscular mycorrhizal (AM) fungi on plant resistance against soil salinity and alkalinity. To fill in such a gap in knowledge, we conducted three experiments to explore (1) whether exogenous melatonin and an AM fungus had interactive effects on plant response to saline-alkaline stress, (2) whether the influence of melatonin on mycorrhizal plant stress tolerance was attributable to effect on the AM fungus, and (3) whether the effect of melatonin application was due to changes in soil salinity and alkalinity. We found interactive effects between melatonin and the AM fungus on alleviating ROS burst, decreasing malondialdehyde content and protecting Leymus chinensis photosynthetic activity through activation of antioxidant enzyme and gene expression (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) in plant shoots and roots. Our results showed that exogenous melatonin promoted spore germination and hyphal length of the AM fungus under Petri-dish conditions. However, exogenous melatonin application did not exhibit significant effects on soil salinity and alkalinity. This study provides an insight into the beneficial effects of exogenous melatonin on saline-alkaline stress tolerance in mycorrhizal L. chinensis through regulating antioxidant systems, protecting photosynthetic activity, and promoting associated AM fungal growth without changing soil salinity and alkalinity. It also reveals potential applications of exogenous melatonin and AM fungi for the restoration of saline-alkaline degraded grassland.

The anthropic interference in aquatic ecosystems favors the disordered colonization of T. domingensis, damaging the production of hydroelectric power and river traffic. Because of this, studies report the efficacy of fungal mycoherbicides, with control rates reaching as high as 90%. Thus, the objective of this study was to evaluate the potential of C. typhae as a mycoherbicide in bio control of T. domingensis, at in vitro and greenhouse conditions. 107 samples of symptomatic T. domingensis leaves were collected in flooded areas of rivers in Brazil, with identification and isolation of the collected fungal species. The concentration of inoculum was determined to evaluate the incidence and severity of the disease, the influence of temperature on mycelial growth and conidia germination, the effect of temperature and leaf wetness period on T. domingensis infection by C. typhae and the host range test in vitro. The growth of the colonies of C. typhae was higher at 25 to 30 ºC. There was no interference of the photoperiod on germination of the spores, but the highest percentage of germination was occurred at 20 ºC. The influence of environmental conditions on infection of inoculated leaves of T. dominguensis revealed that at 15 ºC and the period of leaf wetness of 48 hours the highest incidence of the disease was observed, as well as the severity for the same period of leaf wetness. The specificity test showed that C. typhae is specifically pathogenic to T. domingensis. This the first report of the occurrence of this pathogen in aquatic macrophytes of this species and in T. domingensis, a potential mycoherbicide for the control of this aquatic weed.

Propagation of gametophytes and sporophytes using mechanical fragmentation has been considered a suitable method for mass production of ferns. This study aimed to develop a practical propagation method for Lemmaphyllum microphyllum C. Presl, which is a fern of significant ornamental and medicinal value. Gametophytes were obtained through in vitro spore germination and used for propagation experiments. The gametophyte was mechanically fragmented using a scalpel into small fragments, which were then used to investigate gametophyte proliferation. In addition, the gametophyte was fragmented using a blender and then used to study sporophyte formation. Optimal proliferation conditions of the gametophyte were determined using Murashige and Skoog (MS) basal medium (double-, full-, half-, quarter-strength), Knop medium, and medium components (sucrose, nitrogen sources, activated charcoal), at various concentrations. The fresh weight of the gametophyte was 14-fold higher than that of gametophytes (300 mg) used as culture material, when cultured on double-strength MS. Moreover, 1 g of the gametophyte fragmented in 25 mL of distilled water formed more than 430 sporophytes in a soil mixture in an area of 7.5 cm2. The sporophytes were successfully cultivated in the greenhouse after acclimation. A large-scale production method for L. microphyllum that can be easily implemented in a fern production farm is outlined.

RESUMO A presença de Lasiodiplodia theobromae (Podridão seca) em videiras implantadas em áreas irrigadas da região semiárida brasileira, tem mostrado elevada agressividade ao infectar várias partes das plantas. Os óleos essenciais têm apresentado eficiência no controle de doenças, tanto pela ação fungitóxica, inibindo o crescimento micelial e a germinação de esporos, além da presença de compostos eliciadores. Com isso, o presente trabalho teve por objetivo obter o controle de L. theobromae pela utilização do óleo de Citronela (Cymbopogon nardus L) em diferentes dosagens. O crescimento micelial de L. theobromae foi analisado em placas de Petri contendo o meio batata-dextrose-ágar suplementado com o óleo essencial nas seguintes concentrações: 0; 0,25; 0,5; 1,0; 1,5 e 2,0%. Para avaliação do efeito direto do óleo essencial sobre o desenvolvimento da doença, os cachos de uva foram inoculados com o patógeno e, após 4 horas, aspergidos com soluções contendo as mesmas concentrações descritas anteriormente; posteriormente, com o objetivo de avaliar o potencial do óleo essencial no tratamento preventivo, os mesmos tratamentos foram aplicados em cachos de uva 4 horas antes da inoculação. O óleo de Citronela em todas as concentrações testadas foi capaz de inibir o crescimento micelial de L. theobromae em 100%. No tratamento curativo, com relação a incidência, Citronela 0,25% reduziu 38% na infecção de bagas de cachos de uva inoculadas com L. theobromae, sendo capaz de reduzir a severidade da doença em 56%. No tratamento preventivo, o óleo de Citronela a 0,25% reduziu em 52% a infecção das bagas de uva cv. Itália, reduzindo a severidade da doença em 66,3%. Sendo possível concluir que a concentração 0,25% foi a melhor dosagem testada para o controle da doença com o óleo essencial de Citronela. ABSTRACT Presence of Lasiodiplodia theobromae (dry rot) in vines established in irrigated areas of the Brazilian semiarid region has shown to be highly aggressive when infecting several parts of the plants. Essential oils have shown efficiency in controlling diseases, both by the fungitoxic action, inhibiting mycelial growth and spore germination, and by the presence of eliciting compounds. Thus, the objective of this study was to obtain control of L. theobromae by using citronella oil (Cymbopogon nardus L) at different levels. Mycelial growth of L. theobromae was analyzed in Petri dishes containing potato-dextrose-agar medium supplemented with essential oil at the following concentrations: 0; 0.25; 0.5; 1.0; 1.5 and 2.0%. To evaluate the direct effect of the essential oil on the development of the disease, grape bunches were inoculated with the pathogen and, after 4 h, sprayed with solutions containing the same concentrations described above; subsequently, in order to evaluate the potential of the essential oil in the preventive treatment, the same treatments were applied in grape bunches 4 hours before inoculation. Citronella oil at all tested concentrations was capable of inhibiting the mycelial growth of L. theobromae by 100%. For the healing treatment, considering incidence, 0.25% citronella reduced by 38% the infection in berries of grape bunches inoculated with L. theobromae and was capable of reducing the disease severity by 56%. As regards the preventive treatment, 0.25% citronella oil reduced by 52% the infection in berries of grape bunches cv. ‘Itália’, reducing the disease severity by 66.3%. These results lead to the conclusion that 0.25% was the best concentration tested for disease control with citronella essential oil.

Liberated tetraspores and carpospores of mature plants of Laurencia sp. 1 collected from Kyaikkhami (Lat. 16° 05′ N, Long. 97°34′E) and Setse (Lat. 15°52′ N, Long. 97° 8′ E) coastal areas had been cultured at temperature 25°C under 16L:8D photoperiod using PES medium in 20 ‰ salinity. The development of tetrasporelings in the laboratory cultures stopped after 30 days, whereas that of carposporelings stopped after 20 day. Both tetraspores and carpospores germinate into bipolar sporelings with erect shoot and colourless rhizoidal filaments in Laurencia sp. 1. Moreover, the germination pattern of tetraspores was similar with that of carpospores. However, the growth rate of carposporelings was slower than tetrasporelings. In the present study, the germling stages of both tetraspore and carpospore showed the Fucus type of the germination pattern. The developmental stages of tetraspore and carpospore germination of Laurencia sp. 1 were briefly described.

Based on several modern plant species (Aristolochia clematitis, A. manshuriensis, Alliaria petiolata, Chloranthus japonicus, Symphytum officinale, Ambrosia trifida, Polemonium caeruleum, Plantago major, Populus tremula and P. × berolinensis), grown in botanical gardens of Moscow and Saint Petersburg, the stages of gametophyte and sporoderm development were compared. The most common regularities in the development of male gametophyte and its sporoderm were revealed. It is shown that the thicker the endexine, the later the intine starts to develop. The formation of tubular intine at the first mitosis of male gametophyte can occur after initiation of the intine, as it is observed in spores with endosporous spore germination in gametophyte. The dehydration of a pollen grain that is expressed in deposition of lipids and starch can start before the maturation of sporoderm that is observed in inaperturate pollen grains. Angiosperms show the broadest possibilities of variability in the sporoderm structure without losing the capacity for reproduction.

Banana is an important fruit crop. Fusarium wilt caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) seriously threatens the global banana industry. It is difficult to control the disease spread using chemical measures. In addition, commercial resistant cultivars are also lacking. Biological control is considered as a promising strategy using antagonistic microbes. Actinomycetes, especially Streptomyces, are potential sources of producing novel bioactive secondary metabolites. Here, strain SCA2-4T with strong antifungal activity against Foc TR4 was isolated from the rhizospheric soil of Opuntia stricta in a dry hot valley. The morphological, physiological and chemotaxonomic characteristics of the strain were consistent with the genus Streptomyces. Based on the homology alignment and phylogenetic trees of 16S rRNA gene, the taxonomic status of strain SCA2-4T exhibited a paradoxical result and low bootstrap value using different algorithms in the MEGA software. It prompted us to further discriminate this strain from the closely related species by the multilocus sequence analysis (MLSA) using five house-keeping gene alleles (atpD, gyrB, recA, rpoB, and trpB). The MLSA trees calculated by three algorithms demonstrated that strain SCA2-4T formed a distinct clade with Streptomyces mobaraensis NBRC 13819T. The MLSA distance was above 0.007 of the species cut-off. Average nucleotide identity (ANI) values between strain SCA2-4T genome and two standard strain genomes were below 95-96% of the novel species threshold. Strain SCA2-4T was assigned to a novel species of the genus Streptomyces and named as Streptomyces huiliensis sp. nov. The sequenced complete genome of SCA2-4T encoded 51 putative biosynthetic gene clusters of secondary metabolites. Genome alignment revealed that ten gene clusters were involved in the biosynthesis of antimicrobial metabolites. It was supported that strain SCA2-4T showed strong antifungal activities against the pathogens of banana fungal diseases. Extracts abstracted from the culture filtrate of strain SCA2-4T seriously destroyed cell structure of Foc TR4 and inhibited mycelial growth and spore germination. These results implied that strain SCA2-4T could be a promising candidate for biological control of banana Fusarium wilt.

The interactions between six commonly occurring fungal species in damp or water-damaged houses in southern California were studied. These fungal species were Alternaria alternata, Aspergillus niger, Chaetomium globosum, Cladosporium herbarum, Penicillium chrysogenum and Stachybotrys chartarum. In the damp building materials, S. chartarum was found to be associated with A. niger, C. globosum, and P. chrysogenum but not with A. alternata and C. herbarum. Stachybotrys chartarum showed strong antagonistic effect against A. alternata and C. herbarum and significantly inhibited in vitro growth of A. alternata and C. herbarum but had no effect on A. niger, C. globosum, and P. chrysogenum. Two trichothecenes, produced by S. chartarum, trichodermin and trichodermol, significantly inhibited spore germination and in vitro growth of A. alternata and C. herbarum but had no effect on A. niger, C. globosum, P. chrysogenum and S. chartarum. In the damp building materials (drywall, ceiling tile, and oak woods), S. chartarum significantly inhibited the growth of A. alternata and C. herbarum and had no effect on the growth and colonization of A. niger, C. globosum, P. chrysogenum in these substrata.

Ascophyllum nodosum extracts (ANE) are well-established plant biostimulants that improve stress tolerance and crop vigour, while also having been shown to stimulate soil microbes. The intersection of these two stimulatory activities, and how they combine to enhance plant health, however, remains poorly understood. In the present study, we aimed to evaluate: (1) the direct effect of ANE on the arbuscular mycorrhizal fungus Rhizophagus irregularis, and (2) whether ANE influences endomycorrhization in plants. ANE enhanced development of R. irregularis in vitro, showing greater spore germination, germ tube length, and hyphal branching. Greenhouse-grown Medicago truncatula drench-treated with ANE formed mycorrhizal associations faster (3.1-fold higher mycorrhization at week 4) and grew larger (29% greater leaf area by week 8) than control plants. Foliar applications of ANE also increased root colonization and arbuscular maturity, but did not appear to enhance plant growth. Nonetheless, following either foliar or drench application, M. truncatula genes associated with establishment of mycorrhizae were expressed at significantly higher levels compared to controls. These results suggest that ANE enhances mycorrhization through both direct stimulation of arbuscular mycorrhizal fungus growth and through stimulation of the plant’s accommodation of the symbiont, together promoting the establishment of this agriculturally vital plant–microbe symbiosis.

For soilborne pathogens, germination of the resting or dormant propagule that enables persistence within the soil environment is a key point in pathogenesis. Spongospora subterranea is an obligate soilborne protozoan that infects the roots and tubers of potato causing root and powdery scab disease for which there are currently no effective controls. A better understanding of the molecular basis of resting spore germination of S. subterranea could be important for development of novel disease interventions. However, as an obligate biotroph and soil dwelling organism, the application of new omics techniques for the study of the pre-infection process in S. subterranea has been problematic. Here, RNA sequencing was used to analyse the reprogramming of S. subterranea resting spores during the transition to zoospores in an in-vitro model. More than 63 million mean high-quality reads per sample were generated from the resting and germinating spores. By using a combination of reference-based and de novo transcriptome assembly, 6,664 unigenes were identified. The identified unigenes were subsequently annotated based on known proteins using BLAST search. Of 5,448 annotated genes, 570 genes were identified to be differentially expressed during the germination of S. subterranea resting spores, with most of the significant genes belonging to transcription and translation, amino acids biosynthesis, transport, energy metabolic processes, fatty acid metabolism, stress response and DNA repair. The datasets generated in this study provide a basic knowledge of the physiological processes associated with spore germination and will facilitate functional predictions of novel genes in S. subterranea and other plasmodiophorids. We introduce several candidate genes related to the germination of an obligate biotrophic soilborne pathogen which could be applied to the development of antimicrobial agents for soil inoculum management.

The potential risks of micro/nanoplastics on the ecological environment, particularly aquatic fauna, have been realized in recent years. However, information about its potential effects on aquatic plants is scarce. In this study, a four-week exposure experiment was conducted to investigate the effects of varying polystyrene nanoplastics concentration (PS-NPs, 0-100 μg/mL) on the early development of an endangered aquatic plant, Ceratopteris pteridoides. Fluorescent observations demonstrated that PS-NPs were adsorbed and accumulated on the spore surface of C. pteridoides rapidly and massively with increasing exposure concentration and time. The adsorption and accumulation of PS-NPs on the spore surface posed a negative effect on spore imbibition, causing 2.3-22.4% reduction in final spore size. Spore germination and gametophyte sex differentiation were both negatively affected by PS-NP exposure, resulting in 10.4-88.0% inhibition in germination ratio and 2.9-53.4% reduction in hermaphroditic gametophyte ratio. Additionally, PS-NPs were observed to penetrate into the roots of gametophytes. Higher concentration of PS-NPs (100 μg/mL) can even induce pathological changes on gametophytes, although with a low incidence (4.9%). The results above indicated that exposure to PS-NPs caused a series of disruptions from the spore imbibition to germination and gametophyte stages, and are likely to pose an eco-physiological risk on the reproductive success of endangered ferns.

Myxogastria is a group of protozoa characterized by cellular uninucleate amoeboflagellates (myxamoebae and flagellated swarm cell), acellular multinucleate plasmodia, and stationary spore‐bearing sporocarps. The Stemonitales is a large order in the Myxogastria and contains approximately 230 species, but only 13 species have their completed life cycles observed so far. Here, we described the life cycles of two species in Stemonitales, Stemonitopsis typhina and Stemonitis fusca by culturing in water agar medium and observing the morphogenesis of their spore germination, plasmodium, and sporocarp development. The spore‐to‐spore life cycles of Ste. typhina and S. fusca were completed in approximately 67 and 12 d, respectively. Both species possessed an aphanoplasmodium. However, the spores of Ste. typhina and S. fusca germinated by the V‐shape split and pore methods, respectively. Unlike S. fusca with an evanescent peridium, Ste. typhina produced a shiny persistent peridium which was continuous with the membrane surrounding its stalk. The information will contribute to a better understanding of their taxonomy and phylogeny.

A growing world population requires an increase in the quality and quantity of food production. However, field losses due to biotic stresses are currently estimated to be between 10 and 20% worldwide. The risk of resistance and strict pesticide legislation necessitate innovative agronomical practices to adequately protect crops in the future, such as the identification of new substances with novel modes of action. In the present study, liquid chromatography mass spectrometry was used to characterize Rheum rhabarbarum root extracts that were primarily composed of the stilbenes rhaponticin, desoxyrhaponticin, and resveratrol. Minor components were the flavonoids catechin, epicatechin gallate, and procyanidin B1. Specific polyphenolic mixtures inhibited mycelial growth of several phytopathogenic fungi and oomycetes. Foliar spray applications with fractions containing stilbenes and flavonoids inhibited spore germination of powdery mildew in Hordeum vulgare with indications of synergistic interactions. Formulated extracts led to a significant reduction in the incidence of brown rust in Triticum aestivum under field conditions. Arabidopsis thaliana mutant and quantitative reverse-transcription polymerase chain reaction studies suggested that the stilbenes induce salicylic acid-mediated resistance. Thus, the identified substances of Rheum roots represent an excellent source of antifungal agents that can be used in horticulture and agriculture.

Tissue culture methods using gametophytes are considered the easiest ways to mass-produce fern sporophytes. The aim of this study was to develop a practical propagation method for the ornamental fern, Athyrium sheareri. The gametophytes obtained from in vitro spore germination were used as experimental materials. We used the chopping method to investigate the culturing conditions for proliferating gametophytes and the blending method for evaluating the mass production of sporophytes in mixed soil. Gametophyte proliferation was determined via Knop medium, various concentrations of Murashige and Skoog (MS) basal medium (1, 1/2, 1/4), and media components (sucrose, nitrogen source, and activated charcoal). The fresh weight of the gametophytes increased by more than 24-fold in 1/2 MS medium. In addition, 1 g of gametophyte could produce a maximum of 255.3 sporophytes in a mixed soil of 7.5 cm2 area. Treating gametophytes with exogenous plant growth regulators promoted the formation and growth of sporophytes. The cultivated young sporophytes were acclimated and successfully grown in greenhouses. We developed a mass production protocol for A. sheareri sporophytes suitable for field application, which is expected to have commercial value.

Cheilanthes argentea (S.G. Gmel.) Kunze is a highly valued indigenous/endemic Korean bracken species used for ornamental purposes. In this study, we developed a practical proliferation method for mass production of C. argentea plants using tissue culture. The gametophyte proliferation using the chopping method produced gametophytes that were morphologically identical to those obtained from in vitro spore germination. This new method increased plant fresh weight by more than 40-fold, from 300 mg to 12.7 g, in Murashige and Skoog medium. A blending method was used to produce 74.3 sporophytes in 7.5-cm2 plastic pots using 1 g of gametophytes. Furthermore, addition of exogenous gibberellin promoted sporophyte development and growth, suggesting the possibility of controlling the number of sporophytes formed. However, further studies are needed to explain the effect of exogenous gibberellin, which is closely related to the sex-determining hormone antheridiogen, on the number of sporophytes and its mechanism of action. Our new tissue culture system is capable of mass proliferation of C. argentea gametophytes in vitro and the formation of sporophytes by ex vitro preparation using the generated gametophytes.

The impact of exogenous cytokinins (kinetin, zeatin, 6-benzylaminopurine, and N6-2-isopentenyladenine) on the pattern of Dryopteris filix-mas (L.) Schott spore germination, gametophyte growth and morphology in vitro have been studied. It was found that all studied cytokinins significantly retarded spore germination, inhibited gametophyte growth, caused deformations and decrease in the thallus size, and suppressed the development of reproductive structures and sporophyte growth at the concentration of 10–5 М. The reduction of the hormone concentration to 10–8 М stimulated the gametophyte development, induced cell divisions, particularly in the apical zone, due to which some of thalli were deformed, promoted the production of rhizoids, affected the formation of antheridia and archegonia, and slowed the sporophyte development.

Asexual urediniospore infection of primary cereal hosts by Puccinia graminis f. sp. tritici (Pgt), the wheat stem rust pathogen, was considered biphasic. The first phase, spore germination and appressoria formation, requires a dark period and moisture. The second phase, host entry by the penetration peg originating from the appressoria formed over the guard cells, was thought to require light to induce natural stomata opening. Previous studies concluded that inhibition of colonization by the dark was due to lack of penetration through closed stomata. A sensitive WGA-Alexa Fluor 488 fungal staining, surface creation and biovolume analysis method was developed enabling visualization and quantification of fungal growth in planta at early infection stages surpassing visualization barriers using previous methods. The improved method was used to investigate infection processes of Pgt during stomata penetration and colonization in barley and wheat showing that penetration is light independent. Based on the visual growth and fungal biovolume analysis it was concluded that the differences in pathogen growth dynamics in both resistant and susceptible genotypes was due to light induced pathogen growth after penetration into the substomatal space. Thus, light induced plant or pathogen cues triggers pathogen growth in-planta post penetration.

With rapid development of the construction of nuclear power plants along the coast, the concern of negative effects of potentially unexpected release of nuclides on marine organisms has increased. Cobalt (Co) is one of the crucial nuclides in nuclear polluted seawater. The effect of its presence in seawater on life cycle of macroalgae has seldom been studied. In this investigation, a series of Co concentrations including 1, 10, 100 μg L−1, and 1, 10 mg L−1 (the background concentration of Co in culture seawater was determined to be at the level of 0.75 ± 0.11 μg L−1) were used to test the effects of their presence on spore germination, gametophyte growth and gametogenesis of the important brown macroalga Undaria pinnatifida. It was found that the spore germination rate of 10 mg L−1 group was significantly lower than that of the control group after 1- and 2 days exposure. The gametophyte sizes of 1 and 10 mg L−1 groups were much smaller than that of the control group after 6- and 12-days exposure. Oogonia and juvenile sporophytes were observed to appear in 1, 10 μg L−1 and the control groups after 12 and 15 days, respectively, but not in the higher concentration groups. In the recovery test, sporophytes appeared in the 100 μg L−1 group on the 5th day, but not in 1 and 10 mg L−1 groups. These results demonstrate that presence of Co at high concentrations in seawater disturbs the life cycle by suppressing both the gametophyte growth and gametogenesis in U. pinnatifida.

Arbuscular mycorrhizal fungi (AMF) play important roles in plant community structure and ecosystem functioning. The allelopathic disruption of arbuscular mycorrhizal mutualism is a potentially powerful mechanism by which non-native species can negatively impact native plant diversity. However, there is limited understanding of this mechanism on woody species in forest ecosystems. In this study, we carried out a set of experiments to explore the allelopathy of Eucalyptus urophylla on mycorrhizal mutualists. First, we examined allelopathic effects on the mycorrhizal growth responses of woody species by collecting leachates from the understory of an E. urophylla plantation. Second, we examined if AMF could counteract the allelopathy of E. urophylla by treating the target species with and without aqueous extract of E. urophylla and AMF inoculum. We conducted a third in vitro experiment to characterize the effects of identified putative allelochemicals (IPAs) of E. urophylla on AMF spore germination, namely Glomus mosseae, Claroideoglomus etunicatum and mixed spores extracted from field soil. There was a positive correlation between the stimulatory effects of natural leachates of E. urophylla and the mycorrhizal growth responses of target woody species. AMF could counteract the negative impact of E. urophylla allelopathy at a relatively low concentration. The IPAs of E. urophylla had variable effects on germination of AMF spores, from stimulatory to inhibitory, depending on chemical types and AMF species. Moreover, the AMF G. mosseae was the least sensitive to allelopathic inhibition of E. urophylla IPAs. This study does not support the hypothesis that allelopathy degrades mycorrhizal symbioses. Our study first provides preliminary evidence for a positive correlation between allelopathy and mycorrhizal growth responses and suggests that higher mycorrhizal growth responses could better protect woody species from allelopathic inhibition in E. urophylla plantations.

SUMMARY Percent germination and length of hyphae of germinated Glomus mosseae spores, cultivated on water agar, decreased significantly in the presence of Aspergillus niger; this decrease was independent of any change in pH of the medium. Soluble and volatile compounds produced by A. niger significantly decreased percentage spore germination and the hyphal length of G. mosseae on water agar. The decrease caused by volatile compounds was significantly greater when A. niger was grown on malt extract agar. Shoot dry weights of maize and lettuce plants cultivated in soil in pots, and percentage arbuscular mycorrhizal (AM) root colonization of plants grown either in sand: vermiculite tubes inoculated with G. mosseae spores or in soil in pots with soil inoculum, were unaffected by A. niger when this saprobe was inoculated 2 wk after G. mosseae. Shoot dry weights and percentage AM colonization of plants decreased when the saprobic fungus was inoculated at the same time or 2 wk before G. mosseae. However, the metabolic activity resulting from AM colonization, measured as the percentage of mycelium showing succinate dehydrogenase activity, decreased in all treatments. The population of A. niger decreased when inoculated to the rhizosphere of plants at the same time as, or 2 wk after, G. mosseae, but not when it was inoculated 2 wk before G. mosseae. Our results show that G. mosseae decreases the saprobic fungal population through its effect on the plant, whereas A. niger, by the production of soluble or volatile substances, inhibits G. mosseae in its extramatrical stage.

espanolSe estudio la fase gametofitica de las especies Amblovenatum immersum y Christella subpubescens (Thelypteridaceae) incluyendo la germinacion, el desarrollo morfologico, caracteristicas vegetativas y estrategias reproductivas. El modelo de germinacion para ambas especies se ajusta al tipo Vittaria, mientras que el modelo de desarrollo del gametofito corresponde con el tipo Drynaria. Los gametofitos adultos eran cordados, con multitud de pelos unicelulares y secretores tanto por el margen, como por ambas caras del protalo. Ademas, en C. subpubescens se detectaron otro tipo de pelos aciculares, unicamente en el margen. Los gametangios presentaban el aspecto tipico de los helechos leptosporangiados. En A. immersum todos los gametofitos se desarrollaron como femeninos. En C. subpubescens los gametofitos primeramente son femeninos, con el paso del tiempo se vuelven bisexuales. Se detecto actividad de anteridiogeno en ambas especies, ya que despues del desarrollo de los gametofitos femeninos aparecieron en los alrededores protalos masculinos en fases muy tempranas de desarrollo (con ausencia de meristemo), pero sexualmente maduros. EnglishThe gametophytic generation of Amblovenatum immersum and Christella subpubescens (Thelypteridaceae), including spore germination, morphological development of the gametophytes, major vegetative features and reproduction strategies, was studied. For both species, the spore germination was of the Vittaria type and the developmental pattern was of the Drynaria type. Adult gametophytes were cordate and hairy, with unicellular and secretory hairs located in the margins and both the ventral and dorsal surfaces of the prothalli. C. subpubescens has another type of acicular hairs only in the margin of the prothallus. Gametangia were of the normal type described for leptosporangiate ferns. In A. immersum all the gametophytes were female. In C. subpubescens the gametophytes produced at first instance female gametangia and then became bisexual with time. Antheridiogen activity was observed in both species, suggested by the presence of small young ameristic gametophytes with antheridia surrounding well-developed female ones.

The gametophytes of the Athyriaceae are not very well known, such as Diplazium caudatum. The aim of this work is to analyze the gametophytic phase of this species, which includes germination study, morphological development and reproductive phase. Spores belonging to two different sporophytes from La Gomera, Spain, were mixed and sown in multisporic cultures. Plates have been cultured in chambers with nutritive agar at 25ºC and 12 hours photoperiod. The germination was registered every three days, and the main vegetative and reproductive development was checked throughout the observational period. The germination rate reached a maximum of 58%. The spore germination followed a Vittaria pattern meanwhile prothallial development followed an Adiantum type. Regarding sexual expression, all gametophytes developed archegonia and later some of them developed antheridia becoming bisexual. Los gametofitos de las Athyriaceae no son muy conocidos, tal es el caso de Diplazium caudatum. El objetivo de este trabajo es analizar la fase gametofítica de esta especie, que incluye el estudio de la germinación, desarrollo morfológico y fase reproductiva. Las esporas pertenecientes a dos esporofitos diferentes de La Gomera (España) han sido mezcladas y sembradas en placas de cultivo. Éstas se han cultivado en cámaras con agar nutritivo a 25ºC y 12 horas de fotoperíodo. La germinación se registró cada tres días y se comprobó el principal desarrollo vegetativo y reproductivo durante todo el período de observación. La tasa de germinación alcanzó un máximo del 58%. La germinación de las esporas siguió un patrón de tipo Vittaria, mientras que el desarrollo del prótalo siguió un patrón de tipo Adiantum. En cuanto a la expresión sexual, todos ellos desarrollaron arquegonios, y posteriormente una pequeña parte desarrolló anteridios convirtiéndose en bisexuales.

Strigolactones (SLs) are components of root exudates as a consequence of active release from the roots into the soil. Notably, they have been described as stimulants of seed germination in parasitic plants and of the presymbiotic growth in arbuscular mycorrhizal (AM) fungi, which are a crucial component of the plant root beneficial microbiota. SLs have therefore the potential to influence other microbes that proliferate in the soil around the roots and may interact with plants. A direct effect of SL analogs on the in vitro growth of a number of saprotrophic or plant pathogenic fungi was indeed reported.Here we describe a standardized method to evaluate the effect of SLs or their synthetic analogs on AM and filamentous fungi. For AM fungi, we propose a spore germination assay since it is more straightforward than the hyphal branching assay and it does not require deep expertise and skills. For filamentous fungi that can grow in axenic cultures, we describe the assay based on SLs embedded in the solid medium or dissolved in liquid cultures where the fungus is inoculated to evaluate the effect on growth, hyphal branching or conidia germination. These assays are of help to test the activity of natural SLs as well as of newly designed SL analogs for basic and applied research.

Extracellular Vesicles (EVs) play pivotal roles in cell-to-cell and inter-kingdom communication. Despite their relevant biological implications, the existence and role of plant EVs released into the environment has been unexplored. Herein, we purified round-shaped small vesicles (EVs) by differential ultracentrifugation of a sampling solution containing root exudates of hydroponically grown tomato plants. Biophysical analyses, by means of dynamic light scattering, microfluidic resistive pulse sensing and scanning electron microscopy, showed that the size of root-released EVs range in the nanometric scale (50&ndash, 100 nm). Shot-gun proteomics of tomato EVs identified 179 unique proteins, several of which are known to be involved in plant-microbe interactions. In addition, the application of root-released EVs induced a significant inhibition of spore germination and of germination tube development of the plant pathogens Fusarium oxysporum, Botrytis cinerea and Alternaria alternata. Interestingly, these EVs contain several proteins involved in plant defense, suggesting that they could be new components of the plant innate immune system.

Iso&euml, tes sabatina is an aquatic quillwort endemic to Italy. It is one of the rarest quillworts in Europe, and is critically endangered due to restricted range and to the continuous decline of both population and habitat quality. This study aims to develop an optimized protocol to reproduce and grow I. sabatina sporelings. Mature and immature megaspores were mixed with mature microspores to evaluate the influence of the developmental stage on germination and sporeling development. Two substrates, distilled water and water-agar medium, were tested for germination and sporeling emergence, and three substrates, sand, lake sediment and water-agar, were tested for transplants. A high percentage of megaspore germination (a total of 79.1%) was obtained in both substrates, higher for mature than immature spores. A total of 351 sporelings were produced in distilled water and water-agar cultures, with similar percentages (64.5% and 69.6%, respectively). The development stage of the megaspores affected both germination and sporeling development. Sporeling emergence showed significantly higher percentages in mature megaspores than immature ones (69.6% vs. 11.6%, respectively), with 85% of germinated spores developing sporelings. Only transplants over water-agar medium were successful. This protocol could be useful for the propagation of sporelings as the key step towards the planning of in situ actions to save this Mediterranean quillwort from extinction.

The work is devoted to studying the influence of the type of culture medium and pH on the development of gametophytes Botrychium multifidum in vitro. The spores obtained from sterilized sporangia were suspended in liquid nutrient media with initial inoculum of 10000 spores per 1 ml. Nutrient media tested in the study were composed of full Murashige and Skoog or Knudson mineral salts supplemented with kinetin (1 mg/l) and pH level 4.8-6.4. All stages of development, from spore germination to thallus and gametophyte formation, were observed in tissue culture. A low level of germinating spores was noted.

The effect of water activity (aw), as lowered by different dietary humectants, on the germination of Bacillus subtilis, Bacillus megaterium and Bacillus cereus spores with germinants that act by different mechanisms has been investigated and compared. Germination of spores of these species by all of the germinants investigated was inhibited as aw decreased, with the general order of efficacy for these non-ionic humectants being sucrose > trehalose > glycerol. The effect of lowering aw on germination by germinant receptor (GR)-dependent germinants was not appreciably altered by varying germinant concentrations, was generally not much more effective with spores lacking coats or an outer membrane, and was less pronounced with heat-activated spores. Analysis of the effect of aw on spore germination via different mechanisms showed that GR-dependent germination was least sensitive to aw, while germination via activation of spore cortex peptidoglycan hydrolysis or dipicolinic acid release was more sensitive. However, germination by high hydrostatic pressure was less sensitive to inhibition by low aw, than was germination by other germinants. Examination of the GR-dependent germination of individual spores indicated that aw acted most strongly in inhibiting the commitment step of germination, while exerting smaller effects on dipicolinic acid release or cortex peptidoglycan hydrolysis.

金沢大学理工研究域自然システム, Muscina angustifrons (Diptera: Muscidae) is a mycophagous species that exploits a variety of fungi, including ectomycorrhizal fungi. Larvae of this species have been shown to feed on sporocarps (including spores), and full-grown larvae leave sporocarps and pupate 0-6 cm below the soil surface. In this study, we examined whether M. angustifrons larvae are capable of transporting ectomycorrhizal fungal spores and enhancing ectomycorrhiza growth on host-plant roots. Full-grown larvae were found to move horizontally 10-20 cm from their feeding sites and burrow underground. These wandering larvae retained ectomycorrhizal fungal spores in their intestines, which were excreted following relocation to underground pupation sites. Excreted spores retained germination and infection capacities to form ectomycorrhiza on host-plant roots. In the infection experiments, ectomycorrhizal fungal spores applied in the vicinity of underground host-plant roots were more effective in forming ectomycorrhiza than those applied to the ground surface, suggesting that belowground transportation of spores by M. angustifrons larvae could enhance ectomycorrhizal formation. These results suggested that M. angustifrons larvae act as a short-distance spore transporter of ectomycorrhizal fungi. © 2018., Embargo Period 12 months

Producción Científica, Twenty-one isolates of edible ectomycorrhizal fungi (ECM) of 15 different species were tested in vitro for mycelial growth and spore germination against two isolates each of Fusarium oxysporum and F. verticillioides. The growth of Fusarium isolates was significantly inhibited when co-cultured with most of the 21 ECM fungi tested. Two ECM fungi (Ba-2 and Xf-2) failed to reduce the growth of Fusariumisolates. In paired cultures, growth of all Fusariumisolates was significantly reduced by Rhizopogon roseolus, Suillus luteus, Tricholoma portentosum, Amanita rubescens, Amanita ovoidea, Boletus fragrans and Laccaria laccata. Spore germination of all Fusariumisolates was strongly inhibited by culture filtrates of R. roseolus and the two S. luteus isolates. Different behavior between ectomycorrhizal fungi and Fusarium species, as well as among isolates of the same species was observed in both assays. Inhibition of Fusarium species suggests that several isolates of edible ectomycorrhizal fungi have a high potential for biological control of damping off. The effect of ECM fungi was less evident in the conidial germination assay than in the growth assay, although inhibition was also observed. The methodology presented here can be used as an effective tool for in vitro selection of ectomycorrhizal fungi and in nursery assays., On a testé in vitro 21 isolats de champignons ectomycorhiziens comestibles (ECM) de 15 espèces différentes sur leur capacité à inhiber la croissance mycélienne et la germination des spores de deux isolats de Fusarium oxysporumet de deux isolats de F. verticillioides. La croissance des isolats de Fusarium a subi une forte diminution lorsqu’ils étaient cultivés en paires avec presque tous les 21 champignons ECM testés. Deux champignons ECM (Ba-2 and Xf-2) n’ont pas réduit la croissance des isolats de Fusarium. Dans les cultures en paires, tous les isolats de Fusarium ont vu leur croissance fortement diminuée par Rhizopogon roseolus, Suillus luteus, Tricholoma portentosum, Amanita rubescens, Amanita ovoidea, Boletus fragrans et Laccaria laccata. La germination des spores de tous les isolats de Fusarium a été considérablement réduite par R. roseolus et des filtrats de culture de deux isolats de S. luteus. Le comportement de chacun des champignons ectomycorhiziens a varié selon l’espèce de Fusarium et l’isolat de chacun. L’effet d’inhibition exercé sur les espèces de Fusarium laisse voir que certains isolats de champignons ectomycorhiziens comestibles pourraient être utilisés dans la lutte contrôle biologique contre la fonte des semis. Les effets des champignons ECM auront moins manifestes lors des essais de germination des conidies que lors des essais de croissance, même s’il y a eu une certaine réduction de la germination. La méthodologie que nous présentons ici pourrait aussi servir pour la sélection in vitro de champignons ectomycorhiziens et pour diverses expériences en pépinière., Ministerio de Ciencia y Tecnología - Fondo Europeo de Desarrollo Regional (project AGL2001-1771)

Recent studies have demonstrated that the micro and nanoparticles of chitosan (CS) have an in vitro antifungal effect against filamentous fungus that are of importance in food. This study was made to evaluate the antifungal activity of chitosan nanoparticles, pepper tree essential oil (PEO), and chitosan biocomposites loaded with pepper tree essential oil (CS-PEO), on the in vitro growth of Colletotrichum gloeosporioides. The particles were obtained by nanoprecipitation and the size and superficial charge (Z potential) were evaluated using dynamic light dispersion analysis (DLS). The mutagenic potential and the acute toxicity were also evaluated. The effect on the radial growth, spore’s germination, viability, and damage to the membrane´s integrity, were determined. The effect on the kinetic growth parameters was also determined. Results showed that the CS and CS-PEO particles diameter was 341.2 ± 12.40 and 355.3 ± 25.3 mm, respectively. In vitro assays showed both nanoparticles with a high inhibition potential on C. gloeosporioides, and low mutagenicity and toxicity. At a concentration of 0.160 mg/mL, the CS-PEO biocomposite presented a greater (P