Biology of FUNgi Lecture 16 Happy together? Fungus-microbial symbioses

Transcription

1 Biology of FUNgi Lecture 16 Happy together? Fungus-microbial symbioses Other fungus animal symbioses The specific parasitism a select insect resulted in great interest in Entomophthorales (Zyg.) as a potential biocontrol agent. Entomophaga maimaiga and control of gypsy moths serves as an example. Entomophaga maimaiga is a specialized parasite of gypsy moth which may cause extensive tree defoliation when E. maimaiga allows population densities are high. convenient dispersal. It has both resting diploid spores and haploid conidia. 1

2 Other fungus animal symbioses - predatory fungi We cannot leave the topic of animal and fungus symbioses without talking about the nematode trapping fungi (nematophagous fungi). For example Nematoctonus hamalis, which catches nematode by adhesive lollipops. There are other ways to catch nematodes too: adhesive nets and active and passive rings. A nematophagous fungus with a constricting ring (active structure). Nematoctonus hamalis captures nematodes by adhesive knobs of different shapes and sizes Other fungus animal symbioses predatory fungi What makes many nematophagous fungi so interesting is the fact that they often are lignolytic or soil inhabiting taxa, which need to supplement their nitrogen budget by nematode diet. For example, Hohenbuehlia is a wood decomposing taxon. The high C:N ratio in the woody substrate has applied a tremendous selection pressure for developing means to supplement the N-diet. Therefore, the wood decomposing Hohenbuehlia catches high N resources and dips into the whole nematode community in soil. Nematoctonus anamorph and Hohenbuehlia teleomorph make together a holomorph: the anamorphteleomorph connection - the whole fungus 2

3 Last time... Animals and fungi share common interests. Leaf cutter ants and Tricholoma. Humans and Pleurotus, Agaricus and Lentinus. Insects and fungi. Entomophthorales. Fungus of the day - Taxonomy: Phylum (subphylum) Basidiomycota Order - Polyporales Family - Polyporaceae is the causal agent of root and butt rot. fruiting bodies often form on the downside of the fallen stumps We use this as an example of competition between two different types of fungi - also biocontrol. Before getting too far - what are the polypores. 3

4 Fungus of the day What are the Aphylloporales? Polypores and conks - persistent, woody or leathery basidiocarps. Some are perennial some annual, although many persist in the Trametes versicolor - the turkey tail. A common wood decaying fungus, also nature for quite some time. common in KS. is also a basidiomycete with tubes, not gills on the underside. Fomitopsis pinicola - a perennial conk showing the annual rings in the basidiocarps. Fungus of the day What are the Aphylloporales? In addition to being annual and/or perennial, the majority of aphylloporales bear tubes (instead of gills) on the underside. In summary, aphyllophorales (the polypores) are durable, hard leathery or woody basidiocarps with tubes as the fertile layer (the hymenium). Underside of the Aphyllophorales is somewhat similar to the tubed layer of the Boletes. Underside of the Aphyllophorales has a hymenium with little pores. 4

5 Fungus of the day - H. annosum is a very serious forest pathogen. Two types (s- and p-types). P-type generally infects pines, whereas s-type can knock out other species of conifers and hardwoods. The broad host range and the close to global distribution make H. annosum into a problematic pest. But wait there is more! H. annosum can disperse and colonize by a three different ways. Once colony of the H. annosum establishes, it forms a concentric ring of dead stems. Fungus of the day - Three way H. annosum can spread in the woods 2. Conidia which are produced within a week on colonized wood 1. Numerous basidiospores 3. Root crafting 5

6 Fungus of the day - We can probably, by now, agree that H. annosum is a serious problem if you are a forester. Cut stumps present a nice substrate for basidio- or conidiospores, one colonized tree will establish a decade-lasting infection center. Phelbia gigantea on a cut pine stump. However there is a biocontrol agent against H. annosum: Phlebia gigantea. Phlebia gigantea is a weak pathogen or a saprotroph capable of rapid colonization of cut stumps by basidiospores. It also produces mitospores (oidia) which can further spread Phlebia colonization. Phelbia gigantea oidia. Fungus of the day - There are two ways that Phlebia gigantea can outperform. 1) Just simple occupation of the potential growth space and resource exploitation competition. Since both organisms occupy basically the same niche, having Phlebia on a stump keeps Heterobasidion out. Remember mycorrhizas and C-depletion. Phelbia gigantea on a stump can exclude the lebensraum of. This has been utilized and there is a great application method: basidiospores mixed in the chainsaw oil. The second mode of action is even more cool. Green goo here is the Phelbia gigantea spore suspension 6

7 Fungus of the day - There are two ways that Phlebia gigantea can outperform. 2) Phlebia gigantea is antagonistic to hyphae and contact results in rapid digestion of the H. annosum hyphae. Clever, clever, clever! The red dye indicates where hyphae came in contact with Phelbia gigantea. The hyphae is autolysing. This time Fungus microbe symbioses. Fungi, too, are microscopic. Hence the choice of the taxon du jour. Remember that symbiosis is not always mutualistic. 7

8 Parasites and pathogens of protozoa (amoebas) There are a few zygomycetous taxa that parasitize amoeba. Stylopage rhabdospora traps amoeba with thin, sticky strands, protrudes into the amoeba and forms a haustorium-like assimilative organ. Cochlonema explicatum has a different strategy. It produces sticky spores which attach to amoeba, germinate and invade the amoeba cytoplasm. Dactylella tylopaga, in turn, is a filamentous deuteromycete which catches its amoeboid prey like Cochlonema explicatum. Fungal associations with bacteria Fairly recently a great number of bacteria have been discovered in the fruiting bodies and mycorrhizas of various ectomycorrhizal basidiomycetes. Cantharellus cibarius mycorrhiza Cantharellus cibarius - common yellow Cantharelle has Pseudomonas associated with the mycelium Cantharellus cibarius mycorrhiza (H=Hartig net) and associated Pseudomonas (B=bacterium) 8

9 Fungal associations with bacteria Although currently poorly understood, the fungus bacterium association seems to be mutualistic. Bacterium resides in the mycorrhizal association and produces enzymes necessary for nutrient solubilization. Improved plant performance Greater carbohydrate availability Improved mycorrhizal nutrient uptake Helper bacteria enzymes Fungal associations with other fungi We already talked about the Heterobasidion Phlebia association and the antagonistic, exploitive competition association. Mutualisms among fungi are poorly known and usually refer to one fungus having to process substrate first before it can be utilized by another. There are numerous parasites of other fungi (mycoparasitism) more than 1000 species of fungi parasitize other fungi. Tricholoma viride is a deuteromycete which can penetrate into a soil dwelling hyphae and digest it. Trichoderma viride grows on wood and in soil. 9

10 Fungal associations with other fungi Other well known parasites of other fungi are species in genus Hypomyces. Hypomyces belongs to an ascomycetous order Hypocreales (perithecial ascomycetes) and colonizes various members of Agaricales. Some consider Hypomyces (the lobster mushroom) as a delicacy. However, since we do not know what the original parasitized mushroom was this is like playing Russian roulette. Think if the agaric was a poisonous species of Amanita. Hypomyces lactifluorum is red in color - the lobster mushroom. The red in the surface is the Hypomyces perithecia which contain the asci and ascospores. Summary Antagonistic associations among fungi. Predators of amoeba. Mutualisms with bacteria. Fungal parasites of other fungi. 10