Secondary Spores Research Articles

Innovative sustainable bioreactor-in-a-granule formulation of Trichoderma asperelloides

The advancement of fungal biocontrol agents depends on replacing cereal grains with low-cost agro-industrial byproducts for their economical mass production and development of stable formulations. We propose an innovative approach to develop a rice flour-based formulation of the beneficial biocontrol agent Trichoderma asperelloides CMAA1584 designed to simulate a micro-bioreactor within the concept of full biorefinery process, affording in situ conidiation, extended shelf-life, and effective control of Sclerotinia sclerotiorum, a devastating pathogen of several dicot agricultural crops worldwide. Rice flour is an inexpensive and underexplored byproduct derived from broken rice after milling, capable of sustaining high yields of conidial production through our optimized fermentation-formulation route. Conidial yield was mainly influenced by nitrogen content (0.1% w/w) added to the rice meal coupled with the fermentor type. Hydrolyzed yeast was the best nitrogen source yielding 2.6 × 109 colony-forming units (CFU)/g within 14 days. Subsequently, GControl, GLecithin, GBreak-Thru, GBentonite, and GOrganic compost+Break-Thru formulations were obtained by extrusion followed by air-drying and further assessed for their potential to induce secondary sporulation in situ, storage stability, and efficacy against Sclerotinia. GControl, GBreak-Thru, GBentonite, and GOrganic compost+Break-Thru stood out with the highest number of CFU after sporulation upon re-hydration on water-agar medium. Shelf-life of formulations GControl and GBentonite remained consistent for > 3 months at ambient temperature, while in GBentonite and GOrganic compost+Break-Thru formulations remained viable for 24 months during refrigerated storage. Formulations exhibited similar efficacy in suppressing the myceliogenic germination of Sclerotinia irrespective of their concentration tested (5 × 104 to 5 × 106 CFU/g of soil), resulting in 79.2 to 93.7% relative inhibition. Noteworthily, all 24-month-old formulations kept under cold storage successfully suppressed sclerotia. This work provides an environmentally friendly bioprocess method using rice flour as the main feedstock to develop waste-free granular formulations of Trichoderma conidia that are effective in suppressing Sclerotinia while also improving biopesticide shelf-life.Key points• Innovative “bioreactor-in-a-granule” system for T. asperelloides is devised.• Dry granules of aerial conidia remain highly viable for 24 months at 4 °C.• Effective control of white-mold sclerotia via soil application of Trichoderma-based granules.

Two new species and one new combination of Ophiocordyceps (Hypocreales, Ophiocordycipitaceae) in Guizhou.

Ophiocordyceps is the largest genus in Ophiocordycipitaceae and has a broad distribution with high diversity in subtropical and tropical regions. In this study, two new species, pathogenic on lepidopteran larvae are introduced, based on morphological observation and molecular phylogeny. Ophiocordycepsfenggangensissp. nov. is characterised by having fibrous, stalked stroma with a sterile tip, immersed perithecia, cylindrical asci and filiform ascospores disarticulating into secondary spores. Ophiocordycepsliangiisp. nov. has the characteristics of fibrous, brown, stipitate, filiform stroma, superficial perithecia, cylindrical asci and cylindrical-filiform, non-disarticulating ascospores. A new combination Ophiocordycepsmusicaudata (syn. Cordycepsmusicaudata) is established employing molecular analysis and morphological characteristics. Ophiocordycepsmusicaudata is characterised by wiry, stipitate, solitary, paired to multiple stromata, yellowish, branched fertile part, brown stipe, immersed perithecia, cylindrical asci and cylindrical-filiform, non-disarticulating ascospores.

The dingo (Canis familiaris) as a secondary disperser of mycorrhizal fungal spores

Context Many mycorrhizal fungi are vital to nutrient acquisition in plant communities, and some taxa are reliant on animal-mediated dispersal. The majority of animals that disperse spores are relatively small and have short-distance movement patterns, but carnivores – and especially apex predators – eat many of these small mycophagists and then move greater distances. No studies to date have assessed the ecosystem services carnivores provide through long-distance spore dispersal. Aims In this study, we aimed to investigate whether Australia’s free-ranging dogs (Canis familiaris), including dingoes, act as long-distance spore dispersers by predating smaller mycophagous animals and then secondarily dispersing the fungi consumed by these prey species. Methods To answer this question, we collected dingo scats along 40 km of transects in eastern Australia and analysed the scats to determine the presence of fungal spores and prey animals. Using telemetry and passage rate data, we then developed a movement model to predict the spore dispersal potential of dingoes. Key results We found 16 species of mammalian prey to be eaten by dingoes, and those dingo scats contained spores of 14 genera of mycorrhizal fungi. These fungi were more likely to appear in the scats of dingoes if primary mycophagist prey mammals had been consumed. Our model predicted dingo median spore dispersal distance to be 2050 m and maximum dispersal potential to be 10 700 m. Conclusions Our study indicates that dingoes are providing a previously overlooked ecosystem service through the long-distance dispersal of mycorrhizal fungi. Many of the fungi found in this study form hypogeous (underground) fruiting bodies that are unable to independently spread spores via wind. Because dingoes move over larger areas than their prey, they are especially important to these ecosystem functions. Implications Our novel approach to studying an overlooked aspect of predator ecology is applicable in most terrestrial ecosystems. Similar modelling approaches could also be employed to understand the dispersal potential of both primary and secondary spore dispersers globally. Because this study highlights an unrecognised ecosystem service provided by dingoes, we hope that it will stimulate research to develop a more comprehensive understanding of other apex predators’ ecosystem functions.

A new genus Unguispora in Kickxellales shows an intermediate lifestyle between saprobic and gut-inhabiting fungi

ABSTRACT Kickxellomycotina encompasses two fungal groups: a saprobic group in excrement and soil and an arthropod gut-inhabiting group. The evolutionary transition between these two lifestyles is unclear due to the lack of knowledge on intermediate forms and lifestyles. Here, we describe a new species, Unguispora rhaphidophoridarum, that was isolated from the excrement of cave crickets (Rhaphidophoridae) in Japan. This species has a novel lifestyle that is intermediate between the saprobic and gut-inhabiting groups. The new genus Unguispora is a member of the Kickxellales and characterized by the sterile appendages born on the sporocladium and by the claw-like ornamentation of the sporangiole. Phylogenetic analysis based on 18S and 28S nuclear ribosomal DNA showed that this fungus is distinct from all known kickxellalean genera and is sister to Linderina. The sporangiospore of the new species germinated only in anaerobiosis and grew in a yeast-like form. The yeast-like cells, defined as “secondary spores,” germinated into hyphae in aerobiosis. In the alimentary tract of cave crickets, the sporangiola are attached to the proventriculus (foregut) by the claw-like ornamentation and multiplicate in the same yeast-like form as under culture. We introduce a new term, “amphibious fungi,” to describe fungi that have two life stages, one outside and the other inside the host gut, like U. rhaphidophoridarum. The discovery of an amphibious fungus in Kickxellales, which was formerly considered to be only saprobic, suggests that Kickxellomycotina has evolved in association with the animal gut.

A new microsporidian pathogen, Vairimorpha gastrophysae sp. nov., isolated from Gastrophysa viridula (Coleoptera: Chrysomelidae)

Gastrophysa viridula DeGeer 1775, the green dock leaf beetle, belongs to a group of beneficial insects, which can be used as a classical biological control agent against sorrels (Rumex sp., Polygonaceae). Therefore, any infection by pathogenic organisms in this beetle is undesirable. In the present study, a new microsporidian pathogen isolated from G. viridula was identified based on morphological and ultrastructural characteristics, supported with a molecular phylogenetic analysis. Light and transmission electron microscopy studies indicated that the microsporidium was polymorphic throughout its life cycle. Sporulation stages were not all in direct contact with the host-cell cytoplasm. The fresh single diplokaryotic spores of the secondary sporulation cycle had a long narrow morphology, measuring about 5 × 2.1 µm (n = 50). Octospores produced in the secondary sporulation cycle were also observed. Morphological and ultrastructural characteristics of the life cycle stages place it within the genus Vairimorpha. The phylogenetic tree constructed on the 16S rRNA gene sequence analysis supports the morphological and ultrastructural characteristics and indicates that the pathogen is closely related to the Vairimorpha clade of microsporidia. The pathogen is named Vairimorpha gastrophysae sp. nov.

A new species of Moelleriella from Yunnan Province in Southwestern China

We report a new species, Moelleriella puerensis, a fungal pathogen infecting scale insect nymphs, from Puer City, Yunnan Province, Southwestern China. Its diagnostic characteristics include pale yellow and thin pulvinate stromata, ovoid tubercles processes developing on the periphery of the stroma, a fully immersed perithecia, orange ostioles, cylindrical asci, and filiform ascospores disarticulated into short secondary spores. Teleomorph and anamorph typically existed in the same stroma, exclusively anamorphic stromata, with pale yellow conidiomata aggregated in the center of the stroma and several conidiomata per stroma fusing with neighboring conidiomata and existing paraphyses. Morphological observations and phylogenetic analyses of combined nrLSU, rpb1, and tef-1α sequence data confirmed the validity of M. puerensis.

UvKmt2-Mediated H3K4 Trimethylation Is Required for Pathogenicity and Stress Response in Ustilaginoidea virens.

Epigenetic modification is important for cellular functions. Trimethylation of histone H3 lysine 4 (H3K4me3), which associates with transcriptional activation, is one of the important epigenetic modifications. In this study, the biological functions of UvKmt2-mediated H3K4me3 modification were characterized in Ustilaginoidea virens, which is the causal agent of the false smut disease, one of the most destructive diseases in rice. Phenotypic analyses of the ΔUvkmt2 mutant revealed that UvKMT2 is necessary for growth, conidiation, secondary spore formation, and virulence in U. virens. Immunoblotting and chromatin immunoprecipitation assay followed by sequencing (ChIP-seq) showed that UvKMT2 is required for the establishment of H3K4me3, which covers 1729 genes of the genome in U. virens. Further RNA-seq analysis demonstrated that UvKmt2-mediated H3K4me3 acts as an important role in transcriptional activation. In particular, H3K4me3 modification involves in the transcriptional regulation of conidiation-related and pathogenic genes, including two important mitogen-activated protein kinases UvHOG1 and UvPMK1. The down-regulation of UvHOG1 and UvPMK1 genes may be one of the main reasons for the reduced pathogenicity and stresses adaptability of the ∆Uvkmt2 mutant. Overall, H3K4me3, established by histone methyltransferase UvKMT2, contributes to fungal development, secondary spore formation, virulence, and various stress responses through transcriptional regulation in U. virens.

Stimulation of Hyphal Ramification and Sporulation in Funneliformis mosseae by Root Extracts Is Host Phosphorous Status-Dependent.

A simulation of the environment inhabited by arbuscular mycorrhizal (AM) fungi could provide clues as to how to cultivate these obligate biotrophs axenically. Host intraradical and rhizospheric environments, root extracts and exudates in particular, would be crucial for AM fungi to complete their life cycles. In this study, we analyzed and compared the effects of root exudates (RE) and root extracts (RET) of white clover (Trifolium repens) on the asymbiotic growth of the AM fungus Funneliformis mosseae in vitro, and furtherly analyzed the chemical components of different RET with the LC-MS/MS technique in order to establish an asymbiotic cultivation system for this important and hardly domesticated AM fungus. RET is superior to RE in stimulating spore germination, hyphal elongation and branching, and secondary spore formation (p < 0.05). RET-induced effects were dependent on phosphate supplement levels, and the RET obtained following the treatment with low levels of phosphorus significantly promoted hyphal growth and sporulation (p < 0.05). A few newly formed secondary spores showed limited colonization of white clover roots. The low phosphorus-induced effects could be ascribed to the metabolic adjustment (mainly lipids and organic acids) of white clover roots under low phosphate conditions. Our findings demonstrate that the low phosphate-induced RET boosts the asymbiotic growth of AM fungus, and thus offers an alternative way to fulfill the life cycle of AM fungi asymbiotically.

Asymbiotic mass production of the arbuscular mycorrhizal fungus Rhizophagus clarus

Arbuscular mycorrhizal (AM) symbiosis is a mutually beneficial interaction between fungi and land plants and promotes global phosphate cycling in terrestrial ecosystems. AM fungi are recognised as obligate symbionts that require root colonisation to complete a life cycle involving the production of propagules, asexual spores. Recently, it has been shown that Rhizophagus irregularis can produce infection-competent secondary spores asymbiotically by adding a fatty acid, palmitoleic acid. Furthermore, asymbiotic growth can be supported using myristate as a carbon and energy source for their asymbiotic growth to increase fungal biomass. However, the spore production and the ability of these spores to colonise host roots were still limited compared to the co-culture of the fungus with plant roots. Here we show that a combination of two plant hormones, strigolactone and jasmonate, induces the production of a large number of infection-competent spores in asymbiotic cultures of Rhizophagus clarus HR1 in the presence of myristate and organic nitrogen. Inoculation of asymbiotically-generated spores promoted the growth of host plants, as observed for spores produced by symbiotic culture system. Our findings provide a foundation for the elucidation of hormonal control of the fungal life cycle and the development of inoculum production schemes.

DISPERSAL OF ARBUSCULAR MYCORRHIZAL FUNGI BY BATS IN AN URBAN TROPICAL FOREST FRAGMENT

Associations of arbuscular mycorrhizal fungi (AMF) and plant species may occur in terrestrial and air environments and need an effective dispersal, which occurs mainly by biotic vectors. Studies on the influence of flying animals on this dispersal are scarce, thus, this study aimed to investigate the role of bats in AMF propagule dispersal and the most frequent means of transport. Analyses were performed in dorsoventral hairs and feces of bats in an urban tropical forest fragment in southern Brazil, from April to September 2018. The results were negative for the presence of spores in the hair, but spores of Glomus invermaium and Acaulospora scrobiculata were detected in feces of two bat species, evidencing that they can act as secondary spore dispersers. Efficient dispersal depends on the range extension of the dispersing species, so bats can be important dispersers of AMF, since they have the ability to fly and travel long distances.

Comparative study of the ditrophic interaction between Beauveria bassiana and Plutella xylostella

In the present investigation, hyperparasitic interaction between B. bassiana, TM (MH590235) and P. xylostella was studied through scanning electron microscopy and chromatographic techniques. Dose-mortality responses showed an increase in mortality of larva with an increase in spore concentration. The LC50 value for B. bassiana isolate TM (MH590235) was 2.4 × 107 spores mL-1. The ditrophic interaction between B. bassiana and P. xylostella after 24h revealed the adherence of conidia on stemmata, sensory setae, maxillary palpi and legs. After 48h post-infection (hpi), germination of the conidia and appressorium formation was observed. Formation of hyphae and initiation of fungal networking was observed at 72 hpi. Complete ramification by mycelia and conidiogenesis of B. bassiana was observed over the mycosed cadaver after 168 hpi. Subsequently, typical sympodial conidiophores of B. bassiana bearing secondary spores were also observed. The metabolome profile of healthy larvae of P. xylostella revealed the presence of non-volatile organic compounds (NVOCs) like docosene, nonadecene, palmitic acid and heneicosane. However, the NVOC profile was different in the P. xylostella larvae hyperparasitized by B. bassiana. The metabolites present in the infected cadaver were phthalate esters, hydroxyquebrachamine and lactones.

Myristate can be used as a carbon and energy source for the asymbiotic growth of arbuscular mycorrhizal fungi

Arbuscular mycorrhizal (AM) fungi, forming symbiotic associations with land plants, are obligate symbionts that cannot complete their natural life cycle without a host. The fatty acid auxotrophy of AM fungi is supported by recent studies showing that lipids synthesized by the host plants are transferred to the fungi, and that the latter lack genes encoding cytosolic fatty acid synthases. Therefore, to establish an asymbiotic cultivation system for AM fungi, we tried to identify the fatty acids that could promote biomass production. To determine whether AM fungi can grow on medium supplied with fatty acids or lipids under asymbiotic conditions, we tested eight saturated or unsaturated fatty acids (C12 to C18) and two β-monoacylglycerols. Only myristate (C14:0) led to an increase in the biomass of Rhizophagus irregularis, inducing extensive hyphal growth and formation of infection-competent secondary spores. However, such spores were smaller than those generated symbiotically. Furthermore, we demonstrated that R. irregularis can take up fatty acids in its branched hyphae and use myristate as a carbon and energy source. Myristate also promoted the growth of Rhizophagus clarus and Gigaspora margarita Finally, mixtures of myristate and palmitate accelerated fungal growth and induced a substantial change in fatty acid composition of triacylglycerol compared with single myristate application, although palmitate was not used as a carbon source for cell wall biosynthesis in this culture system. Our findings demonstrate that myristate boosts the asymbiotic growth of AM fungi and can also serve as a carbon and energy source.

UvAtg8-Mediated Autophagy Regulates Fungal Growth, Stress Responses, Conidiation, and Pathogenesis in Ustilaginoidea virens

BackgroundUstilaginoidea virens has become one of the most devastating rice pathogens in China, as well as other rice-growing areas. Autophagy is an important process in normal cell differentiation and development among various organisms. To date, there has been no optimized experimental system introduced for the study of autophagy in U. virens. In addition, the function of autophagy in pathogenesis remains unknown in U. virens. Therefore, the functional analyses of UvAtg8 may potentially shed some light on the regulatory mechanism and function of autophagy in U. virens.ResultsIn this study, we characterized the functions of UvAtg8, which is a homolog of Saccharomyces cerevisiae ScAtg8, in the rice false smut fungus U. virens. The results showed that UvATG8 is essential for autophagy in U. virens. Also, the GFP-UvATG8 strain, which could serve as an appropriate marker for monitoring autophagy in U. virens, was generated. Furthermore, this study found that the ΔUvatg8 mutant was defective in the vegetative growth, conidiation, adaption to oxidative, hyperosmotic, cell wall stresses, and production of toxic compounds. Pathogenicity assays indicated that deletion of UvATG8 resulted in significant reduction in virulence of U. virens. Further microscopic examinations of the infection processes revealed that the severe virulence defects in the ∆Uvatg8 were mainly caused by the highly reduced conidiation and secondary spore formation.ConclusionsOur results indicated that the UvAtg8 is necessary for the fungal growth, stresses responses, conidiation, secondary spore formation, and pathogenicity of U. virens. Moreover, our research finding will potentially assist in further clarifying the molecular mechanism of U. virens infection, as well as provide a good marker for autophagy in U. virens and a good reference value for the further development of effective fungicides based on gene targeting.

Stimulation of asymbiotic sporulation in arbuscular mycorrhizal fungi by fatty acids.

Arbuscular mycorrhizal (AM) fungi are obligate symbionts that depend on living host plants to complete their life cycle1,2. This feature, which leads to their unculturability in the absence of plants, strongly hinders basic research and agricultural application of AM fungi. However, at least one AM fungus can grow and develop fertile spores independently of a host plant in co-culture with the bacterium Paenibacillus validus3. The bacteria-derived substances are thought to act as stimulants or nutrients for fungal sporulation, but these molecules have not been identified. Here, we show that (S)-12-methyltetradecanoic acid4,5, a methyl branched-chain fatty acid isolated from bacterial cultures, stimulates the branching of hyphae germinated from mother spores and the formation of secondary spores in axenic culture of the AM fungus Rhizophagus irregularis. Extensive testing of fatty acids revealed that palmitoleic acid induces more secondary spores than the bacterial fatty acid in R. irregularis. These induced spores have the ability to infect host plant roots and to generate daughter spores. Our work shows that, in addition to a major source of organic carbon6-9, fatty acids act as stimulants to induce infection-competent secondary spores in the asymbiotic stage and could provide the key to developing the axenic production of AM inoculum.

Reducing infection and secondary inoculum of Phytophthora ramorum on Viburnum tinus roots grown in potting medium amended with Trichoderma asperellum isolate 04-22

Phytophthora ramorum is a concern of the ornamental nursery business because it is implicated in the movement on ornamental plants such as rhododendron and viburnum. Since there is a soil phase that infects the roots, above-ground symptoms are not often manifested and easily detected. Government agencies require that a P. ramorum-positive nursery be placed under some type of quarantine until it can demonstrate that it has mitigated P. ramorum. Typical methods of mitigation are often expensive, harmful to the environment, and impractical. Biological control using Trichoderma asperellum isolate 04-22 (Ta 04-22) has been demonstrated to reduce P. ramorum soil populations to below detectable limits when incorporated into soil or potting mix. The purpose of this study was to determine whether Ta 04-22 would reduce Viburnum tinus root infection and reduce secondary sporulation from infected roots. When rooted V. tinus cuttings were planted into potting mix amended with three different final concentrations (1×105, 1×106, and 1×107CFU/cm3 potting mix) of Ta 04-22 and drenched with either a P. ramorum sporangia or chlamydospore suspension, plants with any infected roots declined as the Ta 04-22 concentration increased. This was significant (P=0.039) when P. ramorum chlamydospores were used as the inoculum propagule but not (P=0.143) when sporangia were used. A second application of Ta 04-22 as a top-dressing after 4weeks did not result in a decrease in plants with infected roots. When P. ramorum-infected V. tinus roots were treated with Ta 04-22 grown on wheat bran, Ta 04-22 formulated as a wettable powder, or RootShield® Plus WP, flow-through of P. ramorum secondary inoculum was significantly reduced compared to non-treated controls (P<0.001). A second application did not reduce the secondary inoculum any further. These results demonstrate that various formulations of Ta 04-22 and, to a lesser degree, RootShield® Plus WP can be used as a microbial biological control treatment to reduce infection of V. tinus roots by P. ramorum and reduce plant-to-plant spread by reducing secondary inoculum.

Biodiversity and taxonomy of the pleomorphic genus Alternaria

The genus Alternaria, alternarioid hyphomycetes, comprise a biologically, ecologically, and morphologically rich group of fungi that has suffered from taxonomic flux for many years. The taxonomy of these fungi has been predominately based on conidial characters, which includes shape, color, septation, and patterns of secondary sporulation, and to lesser extent on host association, biochemistry, and metabolites. Recent phylogenetic studies have made significant changes to the systematic taxonomy, the accurate identification of a taxon or group of taxa, within Alternaria by elevating 26 clades to the subgeneric taxonomic status of section. This paper aims to serve as an overview of the historical and contemporary taxonomic status of the alternarioid hyphomycetes with special reference to biology, morphology, and phylogenetic biodiversity. Additionally, we propose to synonymize the genus Pseudoalternaria with Alternaria and elevate this well-supported clade to the taxonomic rank of section, Pseudoalternaria sect. nov., bringing the total number of sections to 27 in order to produce a stable and accepted taxonomy for this diverse genus.

Identification of a novel unpaired histidine sensor kinase affecting secondary metabolism and morphological differentiation in Streptomyces acidiscabies ATCC 49003.

Two-component systems (TCSs) are an important signaling transduction pathway that adapt to changing environments. Commonly, a TCS comprises a sensor kinase that is usually an integral membrane histidine sensor kinase and a response regulator that mediates the cellular responses. Presently, however, we cloned a novel sensor kinase gene (tcsK) that is not adjacent to its cognate response regulator from Streptomyces acidiscabies that produces two secondary metabolites, thaxtomin A and WS5995B, and identified its functional involvement in the production of secondary metabolites and morphological differentiation. The elevated expression and disruption of the tcsK gene enhanced 7.1-fold and almost abolished WS5995B production in S. acidiscabies, respectively, but did not affect the production of thaxtomin A. In addition, spore formation of S. acidiscabies was decreased 120-fold by the disruption of tcsK, and the actinorhodin production of Streptomyces lividans TK24 was increased 5.7-fold by the high expression of tcsK. These results indicate that the novel unpaired tcsK gene may be related to the control of secondary metabolite production and spore formation in actinomycetes.

Endomycorrhizal association of Funneliformis mosseae with transformed roots of Linum usitatissimum: germination, colonization, and sporulation studies

Spores of arbuscular mycorrhizal (AM) fungus Funneliformis mosseae (Nicolson & Gerdemann) Walker & Schuessler were cultured in association with transformed roots of Linum usitatissimum L. (Linaceae) for the first time on modified Strullu–Romand medium (pH 5.5) in monoxenic culture. Germ tubes emerged through the spore wall in 88% of spores after 5 days. Hyphal contact with transformed linum roots was observed 5 days after co-cultivation. Paris-type arbuscules and hyphal coils were seen. Extra-radical branched absorbing structures were common. Terminal and intercalary secondary spores were also formed. Spore viability when assessed using vital dye staining (MTT test) was 83%. Secondary spores that proved viable were subsequently transferred from in vitro to in vivo culture where Arum-type arbuscules, intra-radical intercellular hyphae, and extra-radical spores were observed. The procedure established shows potential in AM inoculum mass production and possibility in application.

Production of conidia of Penicillium camemberti in liquid medium through microcycles of conidiation.

Microcycle conidiation is a survival mechanism of fungi encountering unfavorable conditions. In this phenomenon, asexual spores germinate secondary spores directly without formation of mycelium. As Penicillium camemberti conidia have the ability to produce conidiophores after germination in liquid culture induced by a thermal stress (18 and 30°C), our work has aimed at producing conidia through this mean. Incubation at 18 and 30°C increased the swelling of conidia and their proportion thereby producing conidiophores. Our results showed that the microcycle of conidiation can produce 5×10(8) conidiaml(-1) after 7days at 18°C of culture. The activity of these conidia was checked through culture on a solid medium. Conidia produced by microcycle conidiation formed a normal mycelium on the surface of solid media and 25% could still germinate after 5months of storage.

Basidiospore germination by repetition and saprotrophic mycelia in the gelatinous telial horns of Gymnosporangium sabinae

AbstractThe teliospores of Gymnosporangium sabinae facultatively germinate with basidia or with haploid hyphae. The germination of basidiospores is by means of secondary spores (by repetition) or with haploid hyphae. In the gelatinous telial horns a saprotrophic mycelium is developed, that infected probably the host of the dikaryophase. (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)