Spore Germination in Two Tropical Mosses: Fissidenssp. and Racopilum sp

Optimum germination of spores of a Fissidens species occurredat a relatively higher temperature (30 °C) than the optimumgermination of those of a Racopilum species (25 °C). Subsequentprotonemal growth of the two mosses also showed the same differentialtemperature optima. The high-temperature requirement for germinationof Fissidens spores happens to coincide with the maturationand dispersal of the spores in the dry season, and apparentlyfavours the establishment of new shoots. Fissidens sp, Racopilum sp, tropical mosses, spore germination, temperature adaptation     

Enzymatic Isolation of Protoplasts from Fern Protonemal Cells Stainable with a Fluorescent Brightener

Protoplasts were successfully isolated for the first time fromthe filamentous protonemal cells of ferns after the cells werecultured in contact with both air and medium. Sterilized sporesof Adiantum capillus-veneris and Pteris vittata were inoculatedon a piece of nylon mesh (40- {diaeresis}m mesh) placed on amat of polyester fibers which was soaked in liquid culture medium,and the spores were illuminated from above with continuous redlight. Protonemal cells, exposed to the air during this procedure,could be stained with Calcofluor White, a dye that binds tocell walls. Protoplasts were easily isolated from these protonemalcells by digestion of the cell wall with cellulase and pectinase.A total of 0.8–1.9 x 10⁴ and 0.6–2.0 x 10⁴ protoplastswere obtained from protonemata that originated from 10 mg ofdry spores of Adiantum and of Pteris respectively. Viability,as judged by staining with fluorescein diacetate was more than90% for both species. Staining with 4'6-diamidino-2-phenylindole(DAPI) revealed that about half of the protoplasts of both speciescontained a nucleus. (Received May 22, 1989; Accepted September 5, 1989)     

Isolated Megaspore Tetrads of Stauropteris burntislandica

A new type of fossil spore tetrad, Didymosporites scotti gen.et sp. nov. is described from the Dinantian and Namurian (Carboniferous)of Ireland, Scotland, and England. The spores always occur inthe form of a tetrad composed of two large (presumably fertile)and two minute (presumably abortive) spores, all with cutinizedwalls. Reasons are given for regarding these as the megasporesof the coenopterid fern Stauropteris burntislandica; their distributionindicates a far wider range in time and space than that previouslyknown for this species. Their occurrence as adhering tetradssuggests that Stauropteris burntislandica 'shed' its megasporesstill enclosed in the sporangiumIan interesting analogy withboth Lepidocarpon and the seeds of Pteridosperms.     

Airborne fungi in an Italian rice mill

Summary Studies employing volumetric spore trap (VSP) and gravity settling culture plates (GSC) were conducted in order to analyse the air spora of a rice mill at Pavia, Italy, from October-December 1988. Results revealed a variety of fungal spores belonging to different genera and including recognized rice pathogenic fungi. The most frequent genera by GSC method includedAcremonium, Alternaria, Aspergillus, Aureobasidium, Cladosporium, Epicoccum, Fusarium, Helminthosporium, Mucor, Nigrospora, Penicillium, Rhizopus, Trichoderma, Trichothecium, and some unidentified fungi. Environmental assessment of fungal spores by VSP revealed that the most prevalent fungi were:Alternaria, Cladosporium, Epicoccum, Helminthosporium, Nigrospora, Pyricularia, Tilletia and hyaline, dark and coloured types of ascospores and basidiospores. Airborne fungal spore concentrations were particularly high (5,000–6,000 spores/m³) in the rooms of the rice mill where the initial stages of rough rice transformation take place, and dropped to 2,500 spores/m³ in the last room, where workers are. During a temporary interruption of the working processes, air spora concentration dropped below 1,000 spores/m³.Cladosporium, Epicoccum andNigrospora spores were predominant in all subdivisions of the indoor environments of the rice mill.     

Autotropism in Fungal Spores

Autotropism was examined in germinating spore pairs of Rhizopusstolonifer, Mucor plumbeus, Trichoderma viride, and Botrytiscinerea. When germinated on agar surfaces the first three speciesexhibited negative autotropism, B. cinerea being neutral inits autotropic behaviour. More pronounced negative autotropismwas shown by the first three species when germinated on a filmof Cellophane applied to an agar surface. Under these conditionsB. cinerea displayed positive autotropism. Spore pairs of R. stolonifer germinated on agar containing cellulosepowder or charcoal showed less negative autotropism than onagar alone. Touching spore pairs of each species showed a markedtendency towards cis-ness, i.e. germ-tubes beginning on thesame side of a line joining the two spore centres, under theculture conditions described, the one exception being the reductionin cis-ness recorded when R. stolonifer was germinated on agarcontaining charcoal. Time courses of germination were determined for single sporesand touching spore pairs of R. stolonifer and M. plumbeus anda significant promotion was obtained in the spore pairs as comparedwith the single spores. Although both these species exhibitmarked negative autotropism there was a strong tendency forthe positive germ-tube, i.e. one beginning more nearly towardsits neighbour, to emerge before the negative germ-tube in thosespore pairs having one germtube positive and the other negativein orientation. Also, in R. stolonifer, the replacement of germination-promotersby germination-inhibitors in filtrates from spore suspensionsas they age is correlated with a change from positive to negativeautotropism in germinating members of (+ –) spore pairs. Possible mechanisms are discussed to account for the observedeffects.     

The Isolation and Properties of a Factor in Taro Tuber that Agglutinates Spores of Ceratocystis fimbriata, Black Rot Fungus

A factor which agglutinates spores of Ceratocystis fimbriatain the presence of Ca²⁺ was isolated from taro tuber (Corocasiaesculenta Schott, cv. Shiro). The elemental composition of theisolated factor was as found by analysis: C (33.27%), H (4.27%),O (61.90%), N (0.56%); as calculated for C₆₉H₁₀₆O₉₇N₁: C (33.13%),H (4.27%), O (62.04%), N (0.56%). This factor is composed mainlyof galacturonic acid (85% of its dry weight) and contains arabinose,fucose and an unidentified component as its minor components. The differential spore-agglutinating activity of this factordepends on the pH of the assay medium, differential agglutinatingactivity being present at pH 6.5 toward germinated spores ofvarious strains of C. fimbriata. The differential agglutinationof the spores of these strains changed with the growth stage:Ungerminated spores and hyphae of the strains tested were agglutinatedto the same extent, whereas the germinated spores of these strainswere agglutinated differently. When ungerminated and germinated spores of the strains weretreated with pronase, Macerozyme or phospholipase D, their reactivityto the factor changed. Sonication also caused changes in thereactivity of the spores to the factor; germinated spores ofthe sweet potato strain became highly sensitive to it. Insensitivityto the factor was restored in sonicated spores incubated witha substance released from the spores during sonication. Theseresults are discussed in relation to host-parasite specificity. (Received May 19, 1982; Accepted November 9, 1982)     

The Infection of Pine stumps by Fomes annosus and other fungi

A study of the infection biology of stump-colonizing fungi hasshown that certain species, for instance Fomes annosus, Peniophoragigantea, Stereum sanguinolentum, and several causing blue-stain,initiate infection of fresh stumps by means of air-borne sporeswhich colonize the cut surface. The incidence of natural infectionis reduced considerably by applying creosote to the surfaceimmediately after felling. High resin content of stumps is correlatedwith increased resistance to infection. Marked seasonal variationin the incidence of stump infection by F. annosus and P. giganteawas observed. The spore content of the air, and competitionbetween fungi in stumps, are considered to be important factorsaffecting this variation. Initial colonization of stump roots usually proceeds from thebody of the stump. Invasion of roots by saprophytes presentin the soil or litter also occurs but only many months afterfelling. Crowns of plantation pines may bear many spores of stump-colonizingfungi, including F. annosus. Under the conditions described,the proportion of stump infections ascribable to rain-splash-bornespores was small compared with that caused by wind-borne spores.     

<Emphasis Type="Italic">Polytrichum commune</Emphasis> spores nucleate ice and associated microorganisms increase the temperature of ice nucleation activity onset

Moss spores disperse via wind and have been found previously in precipitation and air samples. Their presence in the atmosphere led to this study’s examining the potential of moss spores to contribute to ice nucleation, a process necessary for ice formation in clouds prior to precipitation. Ice nucleation assays were conducted using Polytrichum commune spores that were either associated with natural assemblages of microbes or extracted aseptically from capsules and subsequently confirmed to be free of culturable microbes. Liquid suspensions of capsule spores and non-sterile spores nucleated ice at temperatures as high as ?12 and ?7 °C, respectively. When capsule and non-sterile spores were heated at 95 °C for 10 min, which killed all culturable microbes on non-sterile spores, both nucleated ice from ?10 to ?13 °C. An additional non-sterile spore sample collected from partially opened capsules in a forested ecosystem (ID, USA) nucleated ice at temperatures as high as ?7 °C, similar to non-sterile P. commune spores. This is the first set of results to indicate that P. commune spores themselves are capable of nucleating ice at temperatures higher than many abiological particles such as mineral dust (≤?15 °C) and that natural assemblages of microbes can increase their ice nucleation efficiency. Future studies aimed at determining the abundance of moss spores in the atmosphere and the identity of ice-nucleating microbes associated with them will provide further insights into the ability of moss spores to impact precipitation patterns.     

The Stimulation of Spore Germination in Agaricus bisporus by Living Mycelium

The stimulation of the germination of Agaricus bisporus sporesby mycelium of the same species has been shown to be due toa volatile metabolite, diffusing into the culture medium andinto the atmosphere. A wide range of other fungi has been foundto affect A. bisporus spores in a similar manner. There wasno evidence . that the stimulant was carbon dioxide. A seven-carbonolefin, isolated from air, which had been passed through culturesof A. bisporus mycelium and dried with phosphorus pentoxide,showed germination-stimulating activity but may have been producedby the action of this drying agent on some other metabolitefrom the mycelium. Volatile materials reported by other workersfrom A. bisporus mycelium and from Saccharomyces cereviseaewere tested and, of these, iso-valeric acid and iso-amyl alcoholwere found to stimulate spore germination of A. bisporus     

Disposition of Pollen in situ and its Relevance to Anther/Pollen Culture

Disposition of pollen in immature anthers of Hordeum vulgareis illustrated by scanning and transmission electron microscopy.Freeze-fracture confirms that the pollen is confined to a uniseriatecolumn aligned against the tapetum. There is no free pollenin the lumen of the anther loculi. In contrast, in Nicotianatabacum and Paeonia lactlflora the pollen is disposed at randomand occupies the whole of each loculus. Freezing preserves thefluid content of the loculi, appearing in fracture profilesas an amorphous matrix in which the pollen is embedded. Thematrix, which generally obscures the tapetum, is present throughoutthe microspore phase but diminishes as the spores enlarge. Itis still present in N. tabacum and H. vulgare at the first pollendivision, fragmentary at this stage in P. lactiflora, but isno longer discernible in any of the species at the onset ofpollen-grain maturation. Pretreatment of excised Hordeum spikes at 4 ?C during the microsporephase, a prerequisite for anther/pollen culture, disrupts thenormal developmental sequence but does not alter the uniseriatedisposition. Before the spores start to divide, however, thetapetum degenerates and the fluid phase is dispersed. The observations are discussed in relation to isolated pollenculture, float culture of anthers and the switch in programmefrom gametophytic to sporophytic development. Key words: Pollen, Tapetum, Freeze-fracture     

A Biochemical Study of Spore Germination in the Blue-green Alga Anabaena doliolum

The spores of Anabaena doliolum formed in light (light spores)and after transfer to darkness (dark spores) are biochemicallydifferent in that the light spores contain chlorophyll a andphycocyanin, while dark spores seem to lack them. The apparentbiosyntheses accompanying dark-spore germination seem to proceedin the following order: RNA, chlorophyll a, phycocyanin andDNA. Results of chloramphenicol treatment indicate that proteinsynthesis precedes RNA synthesis. The biosynthetic events followingRNA synthesis show a requirement for light.     

Gene Activity during Germination of Spores of the Fern, Onoclea sensibilis: RNA and Protein Synthesis and the Role of Stored mRNA

Pattern of ³H-uridine incorporation into RNA of spores of Onocleasensibilis imbibed in complete darkness (non-germinating conditions)and induced to germinate in red light was followed by oligo-dTcellulose chromatography, gel electrophoresis coupled with fluorographyand autoradiography. In dark-imbibed spores, RNA synthesis wasinitiated about 24 h after sowing, with most of the label accumulatingin the high mol. wt. poly(A)^–RNA fraction. There was noincorporation of the label into poly(A) ⁺ RNA until 48 h aftersowing. In contrast, photo-induced spores began to synthesizeall fractions of RNA within 12 h after sowing and by 24 h, incorporationof ³H-uridine into RNA of irradiated spores was nearly 70-foldhigher than that into dark-imbibed spores. Protein synthesis,as monitored by ³H-arginine incorporation into the acid-insolublefraction and by autoradiography, was initiated in spores within1–2 h after sowing under both conditions. Autoradiographicexperiments also showed that the onset of protein synthesisin the cytoplasm of the germinating spore is independent ofthe transport of newly synthesized nuclear RNA. One-dimensionalsodium dodecyl sulphate-polyacrylamide gel electrophoresis of³⁵S-methionine-labelled proteins revealed a good correspondencebetween proteins synthesized in a cell-free translation systemdirected by poly(A) ⁺RNA of dormant spores and those synthesizedin vivo by dark-imbibed and photo-induced spores. These resultsindicate that stored mRNAs of O. sensibilis spores are functionallycompetent and provide templates for the synthesis of proteinsduring dark-imbibition and germination. Key words: Onoclea sensibilis, fern spore germination, gene expression, protein synthesis, sensitive fern, stored mRNA     

Breeding System Studies with Three Species of Anagallis(Primulaceae): Self-incompatibility and Reduced Female Fertility in A. monelli L.

The pollination biology, fruit set and breeding system of Anagallisarvensis, A. parviflora andA. monelli were studied in the fieldand glasshouse. No pollinators were observed at flowers of A.arvensis andA. parviflora , and hand pollinations indicatedthat these species are self-compatible taxa which automaticallyself-pollinate as the petals close at the end of the first day.Flowers of A. monelli were visited by several small halictidbee pollinators and a field diallel with seven plants indicatedthat this species is self-incompatible. Fruit set inA. monelliis correlated with distance to the nearest conspecific neighboursuch that beyond 2 m fruit set is relatively low. The diallelcross, and also an analysis of the number of seeds per capsulefor all plants located within 2 m of a conspecific, indicatedthat about 18% of the population of A. monelli showed low femalefecundity and were thus ‘male dominant’ individuals.Copyright 2001 Annals of Botany Company Primulaceae, Anagallis arvensis, Anagallis parviflora, Anagallis monelli, Mediterranean, breeding system, self-incompatibility, fruit set, female sterility     

Plastid Replication in Vegetative Cells, Sporangia, Spores and Sporelings of Red Algae

Ultrastructural aspects of proplastid and chloroplast replicationare described as seen in sections of vegetative cells, sporangia,released spores and sporelings of the red algae Palmaria palmataand Plumaria elegans. Proplastids in apical vegetative cellsshow internal thylakoid formation from peripheral thylakoidsin both species, and proplastid formation by budding from maturechloroplasts has also been observed. Proplastid replicationby fission has been occasionally observed, and genophore divisionin the stroma of proplastids. In vegetative cells, sporangia,spores and sporelings chloroplast formation from mature plastidscan take place by elongation and fission, or by formation ofa discrete group of thylakoids which become pinched off fromthe parent chloroplast, and by irregular expansions of the parentchloroplasts with subsequent multiple fission. Plastid replication, vegetative cells, sporangia, spores, red algae     

ORIGIN OF AMINO ACIDS CONSTITUTING CELLULAR PROTEIN IN GERMINATING CONIDIOSPORES OF ASPERGILLUS NIGER

Formation of pool amino acids in germinating spores of Aspergillusniger strain 1617 was investigated. The pool amino acids comprisedmainly glutamic acid and alanine. Small amounts of pyruvateand -ketoglutarate were found to increase almost in parallelwith the course of increase in the amount of free amino acidsup to the stage of onset of active protein synthesis. Asparticglutamictransaminase activity was exhibited even in dormant spores andit developed in response to the increase in cellular protein.Alanine-glutamic transaminase activity, on the other hand, waslacking in dormant spores and appeared at the stage of accumulationof amino acids preceding protein synthesis. It was revealed from the experiments with ³⁵S-labeled sporesthat the dormant spores of this fungus contain two unidentifiedsulfur substances, and the sulfur of these substances is incorporatedinto the sulfur amino acids of the protein synthesized in germinatingspores. ¹Present address: Institute of Applied Microbiology, Universityof Tokyo, Tokyo (Received September 11, 1959; )     

Spore Germination Patterns in the Ferns, Cyathea and Dicksonia

Cell division patterns during germination of spores of Cyatheaaustralis, C. cooperi and Dicksonia antarctica were examinedby light microscopy of sectioned materials and by the scanningelectron microscope. In C. australis and C. cooperi the rhizoidwas traced to a small cell formed by an asymmetric divisionof the spore by a wall parallel to its equatorial plane. Incontrast, the rhizoid was formed by a division of the sporeparallel to its polar axis in D. antarctica. In spores of bothgenera, a second division wall oriented in a plane perpendicularto the first gave rise to the protonemal cell. Certain aspectsof germination described here in spores of Cyathea and Dicksoniaare in conflict with the published accounts of spore germinationin these genera. Cyathea, Dicksonia, spore germination, cell division pattern     

Effect of spore concentration on germination and autotropism inTrichoderma hamatum

Summary The effect of spore concentration on spore germination and germtube growth ofTrichoderma hamatum on water agar and on potato dextrose agar (PDA) was studied. Increasing inoculum size up to 10⁹ spores/plate on PDA and up to 10⁷ spores/plate on water agar shortened the incubation period required for germtubes emergence and increased germination rate. However, on water agar germination was inhibited at 10⁸ and was completely arrested at 10⁹ spores/plate. Inhibition in germination of 10⁷ spores/plate was observed on water agar when the plates were preincubated with 10⁹ spores/plate for 5 h or more. Addition of glucose and ammonium nitrate to the water agar medium allowed only 25% of the spores to germinate at 10⁹ as compared to 78% at 10⁷ spores/plate after 8 h of incubation. Addition of polysaccharides to the C+N supplemented medium, significantly increased germination up to 84% as compared to 100% on PDA, after 8 h of incubation. Germlings ofTrichoderma hamatum phialospores exhibited positive autotropism and anastamosis on both media. The phenomenon was positively related to inoculum size, being most pronounced at 10⁷ spores/plate.     

Formation of Radioactive Citrulline during Photosynthetic C14O2-Fixation by Blue-Green Algae

Citrulline has been isolated and identified from extracts ofNostoc muscorum. All members of the Cyanophyceae hitherto investigatedshow a relatively large amount of the CO₂ fixed during photosynthesisin citrulline (ranging as high as 20 per cent. in Nostoc) whencompared to the trace amounts found in the Chlorophyceae. Nostocalso has the ability to fix C¹⁴ in citrulline during dark fixation,but at a rate slower than in light. As no free urea or arginine was found in Nostoc, it is likelythat citrulline is functioning in reactions other than thoseleading to arginine and urea synthesis. Other possible functions for citrulline are briefly discussed.     

The influence of surface wettability on the adhesion strength of settled spores of the green alga enteromorpha and the diatom amphora

In this paper we report on the effect of surface wettabilityon surface selection and adhesion properties of settled (adhered)spores of the biofouling marine alga Enteromorpha and cellsof the diatom Amphora, through the use of patterned self-assembledmonolayers (SAMs). The SAMs were formed from alkanethiols terminatedwith methyl (CH₃) or hydroxyl (OH) groups, or mixtures of thetwo, creating a discontinuous gradient of wettability as measuredby advancing water contact angle. In the case of Enteromorpha,primary adhesion, as measured by the transition from a motilespore to a settled, sessile organism, is strongly promoted bythe hydrophobic surfaces. On the other hand, adhesion strengthof the settled spores, as measured by resistance to detachmentin a turbulent flow cell, is greatest on a hydrophilic surface.In the case of Amphora, there is little influence of surfacewettability on the primary adhesion of this organism, but motilityis inhibited at contact angles     

The effect of volatile and gaseous metabolites of swelling seeds on germination of fungal spores

Effects of volatile and gaseous metabolites of swelling seeds of pea, bean, wheat, corn, cucumber, tomato, lentil, carrot, red pepper and lettuce on germination of spores of five genera of fungi were found to depend rather on the fungal than on the plant genus. Germination of spores ofBotrytis cinerea, Mucor racemosus andTrichoderma viride was most severely inhibited. Spores ofVerticillium dahliae were less sensitive and germination of spores ofFusarium oxysporum was inhibited only in two cases. On the other hand, exudates of pea and bean stimulated germination of spores ofFusarium oxysporum. Also spores ofTrichoderma viride germinated better in an atmosphere enriched with exuded metabolites of swelling lettuce seeds. When carbon dioxide produced by the swelling seeds was absorbed in potassium hydroxide, spores ofTrichoderma viride andVerticillium dahliae did not germinate at all, the inhibitory effects of volatile and gaseous exudates on germination of spores ofMucor racemosus were accentuated, and also the percentage of germinated spores ofFusarium oxysporum decreased. Germination of spores ofBotrytis cinerea was not influenced. Absorption of volatile and gaseous metabolites in a solution of potassium permanganate decreased in most cases their inhibitory effects, particularly inBotrytis cinerea.