Fruiting Body Initiation Research Articles

A DNA Damage Checkpoint Pathway Coordinates the Division of Dikaryotic Cells in the Ink Cap MushroomCoprinopsis cinerea

The fungal fruiting body or mushroom is a multicellular structure essential for sexual reproduction. It is composed of dikaryotic cells that contain one haploid nucleus from each mating partner sharing the same cytoplasm without undergoing nuclear fusion. In the mushroom, the pileus bears the hymenium, a layer of cells that includes the specialized basidia in which nuclear fusion, meiosis, and sporulation occur. Coprinopsis cinerea is a well-known model fungus used to study developmental processes associated with the formation of the fruiting body. Here we describe that knocking down the expression of Atr1 and Chk1, two kinases shown to be involved in the response to DNA damage in a number of eukaryotic organisms, dramatically impairs the ability to develop fruiting bodies in C. cinerea, as well as other developmental decisions such as sclerotia formation. These developmental defects correlated with the impairment in silenced strains to sustain an appropriated dikaryotic cell cycle. Dikaryotic cells in which chk1 or atr1 genes were silenced displayed a higher level of asynchronous mitosis and as a consequence aberrant cells carrying an unbalanced dose of nuclei. Since fruiting body initiation is dependent on the balanced mating-type regulator doses present in the dikaryon, we believe that the observed developmental defects were a consequence of the impaired cell cycle in the dikaryon. Our results suggest a connection between the DNA damage response cascade, cell cycle regulation, and developmental processes in this fungus.

Evaluation of indigenous potent mushroom growth promoting bacteria (MGPB) on Agaricus bisporus production

Mushrooms such as Agaricus bisporus, are cultivated for food worldwide. Fruit body initiation in Agaricus bisporus is a phase change from the vegetative to the reproductive stage which depends on the presence of a casing layer with particular physical, chemical and microbiological properties. The phase change is achieved practically by environmental manipulation and the presence of naturally occurring bacteria such as Pseuodomonas putida. In this study, 274 individual bacterial isolates were collected by screening the casing layer of 14 edible mushroom farms. The isolates were analysed with respect to biochemical properties, organic and inorganic phosphate solubilization, production of siderophore and growth in the presence of volatile compound of 1-octen-3-ol. It was found that approximately 97% of the strains were able to grow in the presence of 1-octen-3-ol and 36% were able to solubilize phosphorus. Among the isolates, 23 strains were selected as potent mushroom growth promoting bacteria (MGPB) for inoculation of the casing layer. Field experiments using these strains showed various promoting effects on production of mushroom. Finally, 2 strains (strains Bt4 and Ps7) showing the highest increase in A. bisporus production, were characterized as Pseuodomonas putida by molecular methods and identified as the best suited growth promoting inoculants for application in production farms for increasing the mushroom yield.

<I>Peniophora pseudonuda</I> is a synonym of <I>P. laeta</I>

Abstract — Peniophora laeta is easily recognized because it is restricted to Carpinus as host in Europe, and the reddish yellow fruitbody is provided with prominent teeth or hyphal pegs, disrupting the bark when developing. P. pseudonuda was earlier not even thought of as related to P. laeta, because fruitbodies are smooth and developing on the bark. Moreover, fruitbody initiation starts with a thin layer of brown-pigmented hyphae on bark surface. This render a bluish tint to the mature fruitbody which is in striking contrast to the orange-yellow basidiomata found in P. laeta. Nevertheless, both ITS sequences and crossing tests show that P. pseudonuda is conspecific with P. laeta. This was confirmed also by similarity in spore, basidia and cystidia morphology.

Biotechnology of morel mushrooms: successful fruiting body formation and development in a soilless system

Morchella spp. ascocarps (morels) are some of the world's most sought-after mushrooms. Successful cultivation of morels is still a rare and difficult task despite over 100 years of effort. Here we provide the first report of successful Morchella rufobrunnea fruiting body initiation and development in laboratory-scale experiments. Mushroom initials appeared 2 to 4 weeks after first watering of pre-grown sclerotia incubated at 16 to 22°C and 90% humidity. Mature fruiting bodies reached 7 to 15 cm in length and were obtained after the five morphological developmental stages of this Morchella species: sclerotium formation, scelerotium germination, asexual spore formation, formation of initial knots and development of the fruiting body.

Successful outdoor cultivation of a photosensitive wild strain of edible Pleurotus ostreatus (Fr.) Kummel (Oyster mushroom) from the Western Ghats region of Goa

AbstractThere is considerable interest in identifying wild tropical strains of oyster mushroomsuseful for cultivation, strain improvement and systematic breeding programme. Duringroutine surveys to identify such strains from Goa’s western ghats, an interesting wild form of Pleurotus ostreatus was found growing on logs of wild Mangifera indica L a novel habitat for the species reported for the first time. After obtaining and screening several pure isolates, a fertile strain BA-50/GUOMS was selected for cultivation under natural outdoor conditions. Spawn prepared on wheat grains was produced within 11 days and was used to ramify sterilized paddy straw as substrate using standard polybag technique. Spawn run was initially slow and took 52 days. Mushroom fruitbodies identical to the original wild type were produced in eight flushes at intervals of 8 to 13 days for each flush over a period of four months. These had pleasant odour, better shelf life, tougher texture, resistance to insects, fungi and bacteria, exhibited photosensitivity by producing brownish pigment in direct sunlight and responded well to outdoor conditions for fruit body initiation with ambient temperature ranging from 23-35° C.

이산화탄소가 잎새버섯의 자실체 발생 및 생육에 미치는 영향

Effects of concentration (500, 800, 1,000 and 1,500 ppm) on the initiation and development of fruit body of Grifola frondosa on sawdust cultivation were studied. Optimum concentrations of carbon dioxide for the initiation and development of the fruit body showed the ranges from 500 to 800 ppm. Fruit body initiation was accelerated at lower than 800 ppm exposure but the maturing of the fruit body was not influenced by above treated concentrations. The higher ratio of primordial formation, faster fruit body initiation and higher yield were obtained at below 800 ppm of level, whereas over 1,000 ppm of levels showed abnormal and lower quality of fruiting bodies. Based on the above results, it is concluded that the favorable level for bag culture of G. frondosa was below 800 ppm.

Le.MAPK and its interacting partner, Le.DRMIP, in fruiting body development in Lentinula edodes

Development in shiitake mushroom, Lentinula edodes, is a unique process and studies of the molecular basis of this process may lead to improvement in mushroom cultivation. Previous studies have identified a number of signal transduction genes related to mushroom development, but those genes have not been well characterized. The present work characterized a developmentally regulated MAP kinase, Le.MAPK, and its interaction with a novel gene, Le.DRMIP in the signal transduction pathway. The expression profiles of these two genes reveal their importance in fruiting body initiation and development; the Le.DRMIP transcript is localized predominantly in the developing young fruiting body and gills, which further signifies its role in cell differentiation during mushroom development.

Expression of the urease gene of Agaricus bisporus: a tool for studying fruit body formation and post-harvest development

Fruit body initials of Agaricus bisporus contain high levels of urea, which decrease in the following developmental stages until stage 4 (harvest) when urea levels increase again. At storage, the high urea content may affect the quality of the mushroom, i.e. by the formation of ammonia from urea through the action of urease (EC 3.5.1.5). Despite the abundance of urea in the edible mushroom A. bisporus, little is known about its physiological role. The urease gene of A. bisporus and its promoter region were identified and cloned. The coding part of the genomic DNA was interrupted by nine introns as confirmed by cDNA analysis. The first full homobasidiomycete urease protein sequence obtained comprised 838 amino acids (molecular mass 90,694 Da, pI 5.8). An alignment with fungal, plant and bacterial ureases revealed a high conservation. The expression of the urease gene, measured by Northern analyses, was studied both during normal development of fruit bodies and during post-harvest senescence. Expression in normal development was significantly up-regulated in developmental stages 5 and 6. During post-harvest senescence, the expression of urease was mainly observed in the stipe tissue; expression decreased on the first day and remained at a basal level through the remaining sampling period.

External ultrastructure of fruit body initiation in Morchella

The external morphological changes occurring during initiation and early stages of fruit body development of a Morchella sp., before the development of asci, were examined by scanning electron microscopy. Four stages of primordial development were distinguished. First, disk-shaped knots of 0.5-1.5 mm were observed on the surface of the substrate. Next, the knot inflated and a primordial stem emerged from its centre. Afterward, the stem lengthened, oriented upward, and two types of hyphal elements developed: long, straight and smooth basal hairy hyphae and short stem hyphae, some of which were inflated and projected out of a cohesive layer of tightly packed hyphal elements. Finally, when the stem was 2-3 mm long, pre-apothecia emerged in the apical end, with ridges and pits having distinguished types of paraphyses. Extracelluar mucilage covered the ridge layer and helped give the tissue its shape and rigidity.

Effects of light on the initiation and development of fruit-bodies in commercial cultivation of Hypsizygus marmoreus

Effects of light on the initiation and development of fruit-bodies in commercial cultivation of Hypsizygus marmoreus

Metabolic function of glycogen phosphorylase and trehalose phosphorylase in fruit-body formation of Flammulina velutipes

Glycogen phosphorylase in the vegetative mycelium of Flammulina velutipes converts glycogen to α-glucose 1-phosphate (G1P) in the colony during fruit-body development. Glycogen may contribute to the synthesis of trehalose as the starting material in the vegetative mycelium during the fruiting process of the colony, and the trehalose produced is translocated into the fruit-bodies as the main carbohydrate substrate for their development. Trehalose phosphorylase activity in the vegetative mycelium was at a relatively high level until fruit-body initiation, suggesting the turnover of this disaccharide during the vegetative stage of the colony development. Trehalose phosphorylase activity in the stipes showed a peak level at the early phase of fruit-body development, suggesting the continuing phosphorolysis of trehalose by this enzyme. The stipes also showed a high specific activity of phosphoglucomutase at a sufficient level to facilitate the conversion of G 1P to α-glucose 6-phosphate (G6P). In the pilei a large amount of G 1P remained until the growth of the fruit-bodies ceased. Trehalase activities in the stipes and pilei were at a very low level, and this enzyme may not contribute to the catabolism of trehalose in the fruit-body development.

Activation of intracellular and extracellular phenol oxidases in photoinduced fruit-body formation of Favolus arcularius

The activation of intracellular phenol oxidase (PO) was associated with the photoinduced fruit-body initiation inFavolus arcularius. The second activation of PO activity was also photoinduced in the rapidly developing stipe after the formation of pileus primordium under light exposure. However, the activity levels in the pileus and the mycelium remained low even in the cultures exposed to light. The extracellular PO activity in the culture filtrate also appears to be developmentally regulated: it rose sharply after primordium formation in the light, then decreased rapidly during further development of the fruit-body.

Fruiting body production in Basidiomycetes.

Mushroom cultivation presents an economically important biotechnological industry that has markedly expanded all over the world in the past few decades. Mushrooms serve as delicacies for human consumption and as nutriceuticals, as "food that also cures". Mushrooms, the fruiting bodies of basidiomycetous fungi, contain substances of various kinds that are highly valued as medicines, flavourings and perfumes. Nevertheless, the biological potential of mushrooms is probably far from exploited. A major problem up to now is that only a few species can be induced to fruit in culture. Our current knowledge on the biological processes of fruiting body initiation and development is limited and arises mostly from studies of selected model organisms that are accessible to molecular genetics. A better understanding of the developmental processes underlying fruiting in these model organisms is expected to help mushroom cultivation of other basidiomycetes in the future.

Effects of light on the initiation and development of fruit-bodies in commercial cultivation of Pleurotus ostreatus (Jacq.: Fr.) Kummer

Effects of light on the initiation and development of fruit-bodies in commercial cultivation of Pleurotus ostreatus (Jacq.: Fr.) Kummer

Conventional histological stains selectively stain fruit body initials of basidiomycetes

A method to identify the earliest stages (initials) of Pleurotus pulmonarius and Coprinus cinereus fruit body formation was developed. Light microscopy and Cryo-SEM were used to confirm that even the smallest structures to take up stain were initials of fruit bodies. An approach combining histological staining (flooding the Petri dish with 1% toluidine blue in 1% boric acid (w/v) for 15 min) and image analysis allowed the number of fruit bodies formed on Petri dishes to be quantified easily. Use of the vital stain Janus green (0.001% aqueous, w/v) allowed continued observation of living tissue so that the proportion of fruit bodies that matured (30%) could be established. The method was also effective on wheat straw cultures and could be used to monitor development of mature fruit bodies. It is a promising tool in the study of physiological processes involved in fruit body initiation.

In the midst of death we are in life: Further advances in the study of higher fungi

Summary Senescence and death of mushroom fruit bodies are the natural terminations of their development but not the end of their life because a new batch of fruit bodies can arise directly from the old. A fungal version of programmed cell death seems to be involved in sculpturing fruit body shapes. Fungal differentiation appears to be quite flexible and greatly influenced by the immediate microenvironment. Techniques are now emerging which will enable the earliest stages in fruit body initiation to be studied.

The onset of the helical arrangement of chitin microfibrils in fruit-body development of Coprinus cinereus

The onset of helical arrangement of chitin microfibrils in the wall was investigated during fruit body development of Coprinus cinereus . The onset was traced back to hyphal knots of 0·1–0·2 mm in diameter, i.e. fruit-body initials in which no differentiation into hyphal tissues was yet discernible. The walls of the hyphal knots were distinguishable from those of hyphae in other developmental phases in that the former contained lower amounts of chitin. The results obtained support our model for the ontogeny of the helical wall structure.

Fruiting in the Higher Fungi

Publisher Summary Large elaborate fruit bodies of higher fungi called mushrooms (brackets or toadstools), have attracted attention and are the objects of taxonomic and morphological studies. In the fruit bodies, specialized cells are generated that have genetically different haploid nuclei fuse to form diploid nuclei. The diploid cells do not propagate but undergo meiosis to form haploid spores. The vegetative mycelium colonizes the substrate, and its growth depends on regularly branching hyphae. In the heterothallic basidiomycetes, fruiting is observed regularly or exclusively in the heterokaryon, also called the secondary mycelium, that arises from a mating between two compatible homokaryons. It ensures that diploid cells (basidia) that are formed in fruit bodies produce recombinant meiotic progeny (basidiospores). Haploid fruiting may occur spontaneously, only under stress conditions such as transfer to nutritionally deficient media or injury, or only after applying fruit-body formation-inducing substances. The chapter describes molecular and biochemical indices of fruiting. Environmental conditions such as light, temperature and ambient carbon dioxide concentrations, affect the initiation and further development of fruit bodies in basidiomycetes. Formation of large fruit bodies in basidiomycetes and some members of the ascomycetes can be considered as a special case of emergent growth in fungi. The commercially most valuable mushrooms—those mostly appreciated for their taste—are borne on mycelia that live in mutual symbiosis with the roots of trees.

Involvement of endogenous glycogen in fruiting of Volvariella volvacea and Pleurotus sajor-caju

Intracellular glycogen was extracted and assayed from the fruit bodies of Volvariella volvacea and Pleurotus sajor-caju at different developmental stages. In both mushrooms, glycogen stored in stipe during the initial primordial stage was consumed for fruiting morphogenesis while glycogen in pileus was first broken down for the differentiation and formation of lamellae but later synthesized and accumulated during hymenial cell differentiation. Glycogen was then packed into basidiospores. As glycogen level in vegetative mycelium was high when fruit bodies emerged in V. volvacea , and numerous fruit-body primordia initiated directly on the explanted stipes of P. sajor-caju containing high glycogen content, these suggested that the level of endogenous glycogen is correlated with initiation of fruit bodies in V. volvacea and P. sajor-caju as in Coprinus cinereus .

Perception and response to gravity in higher fungi--a critical appraisal.

Considering that research on gravitropism in higher fungi has a history of over 100 years, the harvest of established fact is disappointingly meagre. We can be reasonably certain of the following. Hymenomycete 'mushroom' fruit bodies (polypore and agaric) exhibit a number of tropisms of which anemotropism, gravitropism, phototropism and thigmotropism have been clearly demonstrated. At any one time one tropism usually predominates but the inferior tropisms can be demonstrated if the predominating ones can be removed by manipulation of the growth conditions. In ascending order, the hierarchy appears to be: thigmotropism, gravitropism, anemotropism, phototropism. During the course of development of a fruit body different tropisms predominate at different times. The youngest fruit body initials grow perpendicularly away from their substratum. The nature of this tropism is completely unknown but perpendicular growth of fruit body initials has been remarked upon in experiments at a variety of light intensities and in gravitational fields from +/- 0 to 4.5 g. The fruit-body primordium then becomes first positively phototropic but later negative gravitropism predominates. The switch between predominance of the two tropisms has been associated with the onset of sporulation in a number of different studies. The major adjustment of the direction of growth in response to a tropic stimulus is made by the mushroom stem. It is the apex of the stem which makes the most immediate gravitropic response. Gravitropic growth curvatures are limited to the normal growth zones of the stem and seem to depend on re-allocation of available growth resources. If the fruit body is reoriented late in the growth of the stem, it may not be able to respond fully. In these cases gravitropic movements of the cap may still be able to bring the hymenophore back to the vertical. Mechanical forces may influence and contribute to the 'gravitropic' response but this has not been experimentally examined. The hymenophore (gill, tube or tooth) is positively gravitropic and responds independently of the stem. Bracket polypores do not show tropisms but exhibit gravimorphogenetic responses such that gross disturbance leads to renewal of growth to produce and entirely new fruiting structure suitably reoriented to the new spatial position. One experiment performed on an orbiting space station suggests that, in the absence of a light stimulus, gravity may be required for initiation of fruiting in Polyporus brumalis. Otherwise, the indications from both clinostat and space-borne experiments are that the basic form of the mushroom (overall tissue arrangement of stem, cap, gills, hymenium, veil) in agaric and polypore alike is established independently of the gravity vector. Abnormal stem growth has been observed in clinostat cultures of Panus (= Lentinus) tigrinus and Polyporus brumalis, but the morphogenetic event which seems most dependent on gravity is sporulation (in the broadest sense). Cultures of P. brumalis on orbiting space craft fail to produce the poroid hymenophore and in clinostat experiments on the ground even karyogamy was rare in similar cultures. Coprinus cinereus grown on the clinostat was able to produce apparently normal fruit body primordia which failed to produce spores and then aborted, forming a new flush of primordia on the old. Taken together with the clear association between observation of gravitropism and the onset of sporulation, the implication is that commitment to the meiosis-sporulation pathway both requires the gravity vector and couples it in some way to fruit-body growth. There is no convincing evidence for a graviperception mechanism in fungi. There is no evidence for any organised means of communicating the gravitropic stimulus once it has been perceived. Reports of three different experimental studies reveal the authors' conviction that the apparently coordinated expression of gravitropic response is in truth a common, but independent, response by the individual component hyphae of the structure concerned. There is some evidence that in the negatively gravitropic Phycomyces sporangiophore the vacuole floats in the protoplasm. If this is generally true it could affect protoplasmic volumes above and below the vacuole such that a greater proportion of the cell's potential for wall growth was adjacent to the lower wall. This is not only an attractive way of accounting for asymmetric wall growth, but since the relative density of the vacuole can presumably be controlled by regulation of water influx and efflux, it is also an attractive means of accounting for the control of gravitropic responses. Phycomyces also exhibits a response to the mechanical consequences of reorientation which is additional to (and different from) the longer term gravitropic response. [TRUNCATED]