Perithecial Formation in Gelasinospora reticulispora VII: Action Spectra in UV Region for the Photoinduction and the Photoinhibition of Photoinductive Effect Brought by Blue Light

An action spectrum for photoinduction of perithecial formationafter a prior 72 h dark growth period was determined in theUV region with apically growing mycelia of a sordariaceous fungus,Gelasinospora reticulispora. The spectrum exhibited a peak at280 nm. Quantum effectiveness of 280 nm irradiation was ca.1.7 times higher than that of 450 nm light. The number of peritheciainduced by UV radiation was saturated at a lower level as comparedwith blue light. UV radiation having a fluence greater thanthe saturation level decreased the number of induced perithecia.UV radiation that was given after a saturating exposure to inductiveblue light inhibited the inductive effect of blue light. Anaction spectrum for this inhibition exhibited a peak between260 and 270 nm. Monochromatic light beyond 350 nm had no inhibitoryeffect. Inhibitory effects of UV radiation given after inductiveblue light irradiation were observed in the fluence range wherephotoinductive effects of UV radiation became obvious. Therefore,the true height of the UV peak in the photoinduction actionspectrum,when free of distortion from the inhibitory effect, should behigher than the peak obtained in this study. (Received August 20, 1983; Accepted November 4, 1983)     

Perithecial Formation in Gelasinospora reticulispora: IV. Action Spectra for the Photoinduction

Action spectra for photoinduction of perithecia after different lengths of dark period were determined with apically growing mycelium of a sordariaceous fungus Gelasinospora reticulispora. When hyphae were exposed to monochromatic light in near ultraviolet and visible regions, reciprocity between intensity and exposure time was observed within the range of incident energy used. The resulting action spectrum determined after a dark period of 48 hours showed a peak at 460 nm with shoulders at 420 and 480 nm and another peak at 370 nm, indicating minima at 410, 430, and 470 nm. After 72 hours darkness the spectrum was very similar to the above, except that the major peak shifted to 450 nm and the near ultraviolet region was somewhat less effective. In both cases, wavelengths longer than 520 nm showed no effect.     

Rapid blue light regulation of a Trichoderma harzianum photolyase gene.

Photolyases and blue light receptors belong to a superfamily of flavoproteins that make use of blue and UVA light either to catalyze DNA repair or to control development. We have isolated a DNA photolyase gene (phr1) from Trichoderma harzianum, a common soil fungus that is of interest as a biocontrol agent against soil-borne plant pathogens and as a model for the study of light-dependent development. The sequence of phr1 is similar to other Class I Type I eukaryotic photolyase genes. Low fluences of blue light rapidly induced phr1 expression both in vegetative mycelia, which lack photoprotective pigments, and, to a greater extent, in conidiophores. Thus, visible light induces the development of pigmented, resistant spores as well as the expression of phr1, perhaps announcing in this way the imminent exposure to the more damaging short wavelengths of sunlight. Light induction of phr1 in non-sporulating mutants shows that a complete sporulation pathway is not required for photoregulation. The light requirements for photoinduction of phr1 were not altered in dimY photoperception mutants. This suggests that photoinduction of sporulation and of photolyase expression is distinct in their photoreceptor system or in the transduction of the blue light signal.     

New photoresponses of phycomyces

The influence of light on asexual fruiting and mycelial growth of Phycomyces blakesleeanus Burgeff was studied by means of fruiting body counts and size measurements in cultures on solid media under varied incubation conditions. Five types of photoresponses were shown by ATCC Strain 8743a: (a) photoinduction of giant sporangiophores; (b) interference by light with an endogenous system that otherwise induces fruiting when the mycelium approaches the rim of the Petri dish; (c) inhibition of mycelial growth rates by light; (d) inhibition of dwarf sporangiophore induction by light; and (e) postponement by light of death in clones maintained by serial transfer at low temperature. A second strain, designated G5, showed responses comparable to (a), (b), and (d). The magnitudes of the responses were greatly affected by temperature of incubation and available nitrogen (asparagine) supply. The photoinduction of giant sporangiophores could be demonstrated with light of wavelengths between 380 and 480 nanometers but not with 520 nanometers or above. At 480 nanometers, light doses as small as 40 ergs per square centimeter were effective in inducing giant sporangiophores in strain 8743a.     

Bioluminescence characteristics of a tropical terrestrial fungus (Basidiomycetes).

Freshly collected samples of luminous mycelium of a terrestrial fungus from Panama were investigated for their bioluminescence characteristics. Taxonomic identification of fungal species could not be determined because of the lack of fruiting bodies. Fluorescence excited by 380 nm illumination had an emission spectrum with a main peak at 480 nm and additional chlorophyll peaks related to the wood substrate. Bioluminescence appeared as a continuous glow that did not show any diel variation. The light production was sensitive to temperature and decreased with temperatures higher or lower than ambient. Bioluminescence intensity was sensitive to hydration, increasing by a factor of 400 immediately after exposure to water and increasing by a factor of 1 million after several hours. This increase may have occurred through dilution of superoxide dismutase, which is a suppressive factor of bioluminescence in fungus tissue. The mycelium typically transports nutritive substances back to the fruiting body. The function of luminescent mycelium may be to increase the intensity of light from the fungus and more effectively attract nocturnal insects and other animals that serve as disseminating vectors for fungal spores.     

Photocontrol of development by Stigmatella aurantiaca.

Aggregation and fruiting body formation by Stigmatella aurantiaca were stimulated most effectively by low irradiances of blue light between 400 and 500 nm. At higher irradiances, other wavelengths of light, including those in the far-red region of the spectrum, were also effective.     

Bioluminescence characteristics of the fruiting body of Mycena chlorophos

Bioluminescent fungi are widely distributed on land and most belong to the class Basidomycetes. Light of about 530 nm wavelength maximum is emitted continuously. The molecular basis for the light‐emitting process remains unclear. We investigated the characteristics of the bioluminescence using cultivated fruiting bodies of M. chlorophos. Only fresh fruiting bodies exhibited long‐lasting light emission; rapid decay of light emission was observed with frozen and freeze‐dried samples. Freeze‐dried samples can be stored at room temperature under dry conditions and may be useful for the isolation of luciferin. The light emission of the fresh fruiting bodies was maintained in various buffers at varying pH; it could be stopped with pH 4 acetate buffer and could be recovered at pH 6. The isolation of luciferin from the fresh fruiting bodies might be possible by the control of buffer pH. The effect of temperature on the light emission of fruiting bodies indicated that bioluminescence in M. chlorophos may involve enzymatic reaction(s). The solubilization of bioluminescent components from the fruiting bodies could not be achieved with various surfactants. Copyright © 2011 John Wiley & Sons, Ltd.     

The Influence of Light Wavelength on Phase-Dependent Responsiveness of the Photoperiodic Clock in Migratory Blackheaded Bunting

We investigated the phase-dependent effects of light wavelength on photoperiodic clock in the migratory blackheaded bunting. Two experiments were performed, employing a skeleton paradigm (6 hours light : 6 hours darkness : 1 hour light : 11 hours darkness; 6L : 6D : 1L : 11D) at 37 ± 2 lux intensity. In the experiment 1, both 6 and 1 h light pulses were given at the same wavelength, 500 nm (green) or 650 nm (red). A group exposed to both pulses of white light served as control. In the experi-ment 2, the two light pulses were given at two different wavelengths, 6 h at 500 nm (green) and 1 h at 640 nm (red) in one group or vice-versa in the other. There was almost no photoinduction when both light pulses in experiment 1, or 1 h light pulse in experiment 2, were green. On the other hand, birds fattened and testes recrudesced when both the light pulses in experiment 1, or 1 h light pulse in experiment 2, were red. Birds receiving both pulses of white light in experiment 1 showed an intermediate response. Taken together, these results indicate that the photoperiodic clock in buntings is differentially responsive at its various circadian phases to different light wavelengths.     

The Influence of Light Wavelength on Phase-Dependent Responsiveness of the Photoperiodic Clock in Migratory Blackheaded Bunting

We investigated the phase-dependent effects of light wavelength on photoperiodic clock in the migratory blackheaded bunting. Two experiments were performed, employing a skeleton paradigm (6 hours light : 6 hours darkness : 1 hour light : 11 hours darkness; 6L : 6D : 1L : 11D) at 37 ± 2 lux intensity. In the experiment 1, both 6 and 1 h light pulses were given at the same wavelength, 500 nm (green) or 650 nm (red). A group exposed to both pulses of white light served as control. In the experi-ment 2, the two light pulses were given at two different wavelengths, 6 h at 500 nm (green) and 1 h at 640 nm (red) in one group or vice-versa in the other. There was almost no photoinduction when both light pulses in experiment 1, or 1 h light pulse in experiment 2, were green. On the other hand, birds fattened and testes recrudesced when both the light pulses in experiment 1, or 1 h light pulse in experiment 2, were red. Birds receiving both pulses of white light in experiment 1 showed an intermediate response. Taken together, these results indicate that the photoperiodic clock in buntings is differentially responsive at its various circadian phases to different light wavelengths.     

Successful large-scale production of fruiting bodies of Laetiporus sulphureus (Bull.: Fr.) Murrill on an artificial substrate

Laetiporus sulphureus is an edible wood-rotting basidiomycete fungus whose fruiting bodies contain substances with verified therapeutic evidences and large amounts of α-(1 → 3)-glucan which is used as an effective inducer of microbial α-(1 → 3)-glucanases. However, production of mature fruiting bodies of this species under artificially controlled conditions has not been reported until now. Here, we provide the first report of successful initiation and development of L. sulphureus fruiting bodies in large-scale experiments. Twelve Laetiporus strains were isolated from a natural habitat. A synthetic log production system with a substrate composed of a mixture of sawdust enriched with organic and inorganic additives was developed. It was found that shocking the fungus mycelium with cold water or low temperature was the only suitable method for forced fruiting of L. sulphureus strains. Primordia of two strains were initiated already after 5–6 days from induction, and after another 2 days, they began to develop into fruiting bodies. Carpophores appeared fastest on substrates with high organic supplementation (40–45 %) and a low moisture content (40 %). The resulting mature fruiting bodies reached a weight of 200–300 g. The method of cultivation presented in this paper opens the way to commercial production of this valuable basidiomycete.     

Pheromone produced by the myxobacterium Stigmatella aurantiaca.

An extracellular, diffusible signaling molecule (pheromone) was produced by Stigmatella aurantiaca during fruiting body formation. The pheromone decreased the aggregation period in both the light and the dark and substituted for light in stimulating the maturation of aggregates into fruiting bodies. The cells were more sensitive to lower concentrations of pheromone in the light than in the dark, possibly explaining the stimulation of aggregation and fruiting body formation by light. The pheromone also interacted cooperatively with GMP to shorten the aggregation period. The pheromone behaved chemically as a low-molecular-weight lipid.     

Photomorphogenesis in<Emphasis Type="Italic"> Phycomyces</Emphasis>: differential display of gene expression by PCR with arbitrary primers

The zygomycete fungus Phycomyces blakesleeanus develops two types of fruiting bodies of very different size, macrophores and microphores. Blue light stimulates macrophorogenesis and inhibits microphorogenesis. I have adapted a method based on the polymerase chain reaction with arbitrary primers to investigate the role of differential gene expression during photophorogenesis in Phycomyces. Several cDNAs for genes induced in vegetative mycelium have been observed, but only one gene induced by blue light has been detected. I have demonstrated the feasibility of this approach by the isolation of a cDNA segment for the heat-shock protein HSP100 that is induced by blue light at the onset of sporangiophore development. The heat-shock protein HSP100 is an ATP-binding protein that has the ability to disassemble protein complexes. In plants, the gene for HSP100 is induced by light. The cDNA segment for HSP100 obtained from Phycomyces is 686 bp long and the predicted amino acid sequence contains one of the ATP-binding sites.     

THE ROLE OF LIGHT IN FRUCTIFICATION OF THE BASIDIOMYCETE CYATHUS STERCOREUS

Fructification in cultures of Cyathus stercoreus (Schw.) de Toni is a process in which photochemical reactions are involved. The amount of light energy required for fruiting to take place is a constant. This photoinductive constant is approximately 17200 foot-candle-hours considering optimum temperature (25 C) and light-saturation effect with reference to light intensity (240 ft-c). It is hypothesized that photoinduction becomes operative when a hypothetical “photoreceptive precursor” develops in the mycelium. The development of such a precursor is believed to occur when conditions unfavorable for good vegetative growth (e.g. shortage of food supply) develop in the culture. Internal metabolic pathways then shift to favor the production of the photoreceptive precursor. A linear function is derived which characterizes the biological photoinduction of fruit-body formation.     

Sex, light and carotenes: the development of Phycomyces.

Phycomyces blakesleeanus is known for the elaborate behaviour of its sporangiophores (fruiting bodies). Sporangiophore development is exquisitely sensitive to blue light, easy to describe quantitatively, pliable to genetic and biochemical research, and reminiscent in many details of other photoresponses in the same and in other organisms. The developmental and behavioural processes of Phycomyces share a number of genes. A combinatorial use of gene expression appears to be the basis for the complexities observed in this fungus.     

The influence of light wavelength on reproductive photorefractoriness in migratory blackheaded bunting (Emberiza melanocephala).

There are two effects of long day length on reproductive responses in birds, one is the photoinduction of gonadal growth and maturation and the other is the induction of gonadal regression and photorefractoriness. Although it is likely that the same photoreceptors are involved in the photoinduction of gonadal growth and the onset and maintenance of photorefractoriness. and so the influence of wavelength should be similar, this has not been investigated. Therefore, we investigated the influence of light wavelength on reproductive photorefractoriness in the migratory male blackheaded bunting held under long photoperiods. In mid May, when photoperiod was approximately 14L:10D (14 hours light:10 hours darkness), eight groups of sexually mature birds were moved indoors on an artificial photoperiod of 14L:10D (L - 450 lux. D - 0 lux). Then after 3 weeks, for six groups, a 4-h light period in the morning (zt 0-4; zt 0 [zeitgeber time 0] refers to the beginning of lights-on period) or in the evening (zt 10-14) was substituted with green (428 nm), red (654 nm) or white light at 16 +/- 2 lux intensity. Of the remaining two groups, one was maintained on 14L: 10D and the other transferred to 10L:14D: these served as controls. At the end of 4 weeks, all birds were found to have undergone testicular regression, irrespective of LD cycle they were exposed to. When these gonadally regressed birds were subjected to 16L:8D for another 4 weeks, to test their responsiveness to the stimulatory effects of long day lengths, only those exposed to 10L:14D and 14L:10D with a 4-h green light period showed testicular regrowth. On the other hand, birds exposed to 14L:10D with a 4-h white or red light period remained fully regressed, similar to 14L:10D controls. Except for some individual difference, there was no difference in response between the groups that received a 4-h light period in the morning and that received it in the evening. These results suggest that the wavelengths of light influence induction of buntings from the photosensitive state into the photorefractory state. Whereas the short light wavelengths facilitated recovery from the photorefractoriness, the long light wavelengths were more effective in maintaining the photorefractoriness.     

Preservation affects the vegetative growth and fruiting body production of <Emphasis Type="Italic">Cordyceps militaris</Emphasis>

Cordyceps militaris is a model species of Cordyceps fungi, and has been traditionally used as an edible and medicinal fungus due to its richness of bioactive and pharmacological metabolites. The fruiting bodies of this fungus are widely used as healthy food and nutrition supply. In industrial production, fruiting bodies are cultivated on artificial media, but their yield and quality are usually affected by the quality of fungal strains. In this study, the effect of colony growth rate of the fungal strains, fungal age and repeated subculturing on the fungal biomass accumulation was investigated. The results indicated that the fungal biomass was positively correlated with the colony growth rate and not affected by fungal age and the repeated subculturing. The preservation conditions for stock cultures, including choice of cultures, lyophilization, temperature and protective agents were optimized based on the mycelial formation and conidia production in artificial inoculum. The development of fruiting bodies from the fungal strains stored under the optimized preservation conditions were further analyzed to determine the ideal time period of preservation. Results indicated that storing the fungus at 4 °C could maintain the fungal vitality and fruiting body producing capacity for at least 12 months. This study established practical criteria of fungal inoculum for artificial cultivation of fruiting body and provided a simple and efficient preservation method for C. militaris. The results may shed light on preservation for other Cordyceps species and other edible fungi.     

Fluence and wavelength requirements for Arabidopsis CAB gene induction by different phytochromes.

The roles of different phytochromes have been investigated in the photoinduction of several chlorophyll a/b-binding protein genes (CAB) of Arabidopsis thaliana. Etiolated seedlings of the wild type, a phytochrome A (PhyA) null mutant (phyA), a phytochrome B (PhyB) null mutant (phyB), and phyA/phyB double mutant were exposed to monochromatic light to address the questions of the fluence and wavelength requirements for CAB induction by different phytochromes. In the wild type and the phyB mutant, PhyA photoirreversibly induced CAB expression upon irradiation with very-low-fluence light of 350 to 750 nm. In contrast, using the phyA mutant, PhyB photoreversibly induced CAB expression with low-fluence red light. The threshold fluences of red light for PhyA- and PhyB-specific induction were about 10 nmol m-2 and 10 mumol m-2, respectively. In addition, CAB expression was photoreversibly induced with low-fluence red light in the phyA/phyB double mutant, revealing that another phytochrome(s) (PhyX) regulated CAB expression in a manner similar to PhyB. These data suggest that plants utilize different phytochromes to perceive light of varying wave-lengths and fluence, and begin to explain how plants respond so exquisitely to changing light in their environment.     

Autofluorescence of the fungus <Emphasis Type="Italic">Morchella conica</Emphasis> var. <Emphasis Type="Italic">rigida</Emphasis>

Autofluorescence (primary fluorescence (AF)) of fruiting bodies and stems of the fungus Morchella conica var. rigida was studied by fluorescence microscopy including sporangia and ascospores. The ascospores were characterized by a weak green–yellow AF at blue excitation. Using a green excitation, no AF was observed. The hyphae located under the layer of asci with ascospores exhibited a higher primary fluorescence, namely their walls that had green-yellow color at blue excitation. Also, their red AF observed when a green excitation was used was significant. Similarly, the hyphae located in the fungal stem exhibited a significant AF, especially their walls when the blue light was used for excitation. In addition, large, yellow-to-yellow/green, oval-to-round bodies with strong fluorescence were detected whose morphological equivalents were not clearly visible in the white halogen light. The AF of the fungus M. conica var. rigida was lower compared with the other higher fungi studied so far.     

Cell patterning in branched and unbranched fruiting bodies of the cellular slime mold Polysphondylium pallidum

Cell patterning, the percentage of spores and stalk cells, was measured in branched and unbranched asexual fruiting bodies of Polysphondylium pallidum. Unlike D. discoideum, where small and large fruiting bodies are more stalky than average-sized fruiting bodies, the overall cell patterning was the same in branched and unbranched fruiting bodies of all sizes in P. pallidum. Light greatly increased the numbers of fruiting bodies in P. pallidum per unit area (or decreased aggregation territory size) so that most fruiting bodies formed in the light were small and unbranched. By contrast, light had little effect on the cell patterning of P. pallidum, although there was a slight increase in the percentage of stalk cells in the light compared to the dark. This indicates that the mechanisms governing light sensitivity of aggregation territory size and cell patterning have different components in P. pallidum. The accuracy of cell patterning of individual branches of branched fruiting bodies was so imprecise as to leave doubt that patterning is occurring at the branch level. Individual whorls of branched fruiting bodies had a greater percentage spores (90%) than whole fruiting bodies (78%) and the cell patterning was relatively imprecise. Only in whole fruiting bodies was the spore:stalk ratio highly correlated. These findings are consistent with cell pattern determination operating at the whole aggregate level, rather than at the individual whorl or branch level in P. pallidum.