Take-off of Mould Spores in Relation to Wind Speed and Humidity

Using horizontal tube-cultures of various moulds belonging tothe genera Thamnidmmt, Phymatotrichum, Trichotheciwm, Ptptocephalis,Trichoderma, Mucor and Mycogone, the take-off of dispersal units(usually spores) under the influence of air currents of variousspeeds and of different humidities has been studied. It is foundthat in all the dry-spore forms the number of spores set freeincreases as the speed of the air stream rises. Further, atany given air-stream rate, the numbers of spores set free aregreatest in the first interval of time and rapidly fall offin subsequent intervals. In all species, spores are more readilyset free in air streams of relatively low as compared with thoseof relatively high humidity. Although Trichoderma viride hasbeen regarded as a slime-spore fungus, its conidia can readilybe blown from the conidiophores. No spores could be inducedto take off from Mucor ramarmianus even at the highest air speedsused.     

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)     

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     

Sex-ratio differences in Mnium hornum Hedw. and M. undulatum Sw. in relation to spore germination and vegetative regeneration

As Mnium undulatum was shown to be homosporous, it was concludedthat neither male nor female derived an advantage from sporesize that might be related to the observed excess of femaleplants. The rate of germination was greater at 20 °C thanat 10 °C in M. hornum and M. undulatum, and was also reducedin short days (7.25 hours) at both temperatures. Spores of M.undulatum germinated more slowly than those of M. hornum undereach of the environmental regimes used. Isolated spores of M.undulatum showed a ratio of 1: 4.1 compared with 1: 0.89 inM. hornum. The excess of female plants of M. undulatum thathad been established by the end of germination, was maintainedamongst the first protonemal buds produced (1: 3.5), whereasan excess of male M. hornum was observed in the first protonemalbuds (1: 0.45). Frost reduced the rate of germination in M.undulatum, but unlike desiccation did not affect the final percentage.Male and female were amongst the spores which survived desiccationat 10 °C. Regeneration of detached leaves occurred more rapidly in M.undulatum than in M. hornum, and no difference between maleand female was detected. It was found that frost prior to orduring regeneration did not produce long-term harmful effectsin M. undulatum. None of the young male gametophytes producedby regeneration from leaves survived desiccation, compared with77 per cent of similarly produced female gametophytes.     

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)     

金龟子绿僵菌MaYTTR-04菌株对松墨天牛成虫的致病力

松墨天牛Monochamus alternatus Hope是重大森林植物检疫性病害——松材线虫病的主要媒介昆虫。采用跗节接种法测定金龟子绿僵菌Metarhizium anisopliae MaYTTR-04菌株对松墨天牛成虫的致病力。结果表明： 在恒温条件下,松墨天牛第6天开始死亡,第18天～21天为死亡高峰期,每头成虫接种孢子量为2.3×10⁶±0.2×10⁶时成虫的死亡率第18天达85%,第21天达95%; 时间效应指标值LT₅₀为14.7天。室内自然变温条件下,松墨天牛第3天出现死亡,第15天～21天为死亡高峰期,每头成虫接种孢子量为2.3×10.6±0.2×10⁶时的死亡率在第15天达85%,第21天达100%;时间效应指标值LT₅₀为12.9天。林间套笼21天后,菌液处理的成虫平均死亡率为60%,僵虫率为48.9%;而通过无纺布菌条的成虫死亡率为86.7%,僵虫率为75.6%。表明MaYTTR-04菌株对松墨天牛成虫有强的致病力,且在较高变温环境温度下致病力更强。结果说明该菌株可作为生产性菌株应用于林间防治松墨天牛。     

Short-term effects of cytokinins on the lipid fatty acids of green leaves

Isolated shoots of Coleus blumei and isolated leaves from thisspecies and from Impatiens sultani were fed zeatin for differentperiods. High doses of the hormone (100 µg/ml) causeda measurable effect on lipid fatty acid composition after atwo-hour feeding period in isolated leaves of Coleus. The maximumeffects were at 20–30 µg zeatin taken up per g freshweight. With the leaves of Impatiens, higher doses of the hormonewere needed to obtain optimal effects. In both species, theproportion of linolenic acid increased and that of palmiticacid decreased. For higher concentrations, the reverse was true.The effects of the hormone on the fatty acids of glycolipidswere more apparent than on those of phospholipids. The resultsare discussed in view of the general importance of dose-responsecurves for cytokinin effects and the possible effects on cellmembranes. (Received November 11, 1978; )     

Germination and outgrowth of Schizosaccharomyces pombe ascospores isolated by Urografin density gradient centrifugation.

A simple method for the isolation of single ascospores of the fission yeast Schizosaccharomyces pombe was examined. Single spores in the 7-day-old sporulating culture of a homothallic strain were separated from remaining vegetative cells by isopycnic centrifugation in the linear gradient from 10 to 60% of Urografin solution at 700 X g for 20 min. Protein content of isolated spores was very low as compared with that of vegetative cells. The isolated spores germinated through the following steps when cultured in a liquid medium at 25--35 degrees C; loss of refractility (darkening) under a phase-contrast microscope, spherical growth (swelling), emergence of germ tubes, elongation of germ tubes, cell plate formation, and cell separation. The absorbance at 650 nm of the spore suspension initially decreased, accompanied by darkening of spores, and then increased with spherical growth. The germination rate of isolated spores reached almost 100%.     

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.     

Digitoxin Biosynthesis in Isolated Mesophyll Cells and Cultured Cells of Digitalis

In the laminae of Digitalis, most of the digitoxin present isfound in the mesophyll. A new method for determining the amountof digitoxin biosynthesis using a digitoxin antibody was devisedto estimate this activity in isolated mesophyll cells and culturedcells. Isolated mesophyll cells showed significant activity,which suggests that the site of biosynthesis and the accumulationof cardenolides in a lamina of Digitalis is mainly in the mesophyllcells. Of five liquid cultures of D. purpurea; green shoot-formingcultures, white shoot-forming cultures, root-forming cultures,undifferentiated green cells and undifferentiated white cells,the green shoot-forming cultures had the highest activity. Thewhite shoot-forming cultures had about one-third the activityof the green shoot-forming cultures, and the other three cultureshad very low activity. No stimulatory effect of light was foundduring the 48-h incubation. (Received January 19, 1984; Accepted June 8, 1984)     

Studies on the control and properties of ornithine transcarbamylase in germinated spores of Geotrichum candidum

The effects of arginine and urea on the levels of ornithinetranscarbamylase (OTC) were investigated in relation to thephysiological functions of this enzyme in Geotrichum candidum.OTC was repressed in germinated spores to half of its initiallevel when exogenous arginine exceeded 12 mM. The repressionof OTC could not be correlated with intracellular arginine concentration.The addition of urea at the final concentration of 0.035 M increasedthe specific activity of OTC by 5.5 and 2.5 fold as comparedto enzyme levels in arginine-repressed spores and control sporesrespectively. Simultaneous addition of urea and arginine duringgermination prevented either arginine repression or urea inductionof OTC. The enzyme was partially purified from germinated sporesand isolated as a single protein band after disc electrophoresis.Two distinct pH optima for the forward reaction (pH 8.8–9)and backward reaction (pH 7.8) were found. Km values for ornithineand carbamyl phosphate were 5 x 10^–3 M and 6.8 x 10^–4so respectively. The Km for citrulline in the catabolic directionwas 1 x 10^–2 M. Enzymes obtained from cell-free extractsof germinated spores could synthetize ATP from citrulline andADP under physiological conditions by coupling the phosphorolysisof citrulline with carbamate kinase activity. The initial rateof germination was stimulated in the presence of citrullineas the sole nitrogen source, as compared to arginine, glutamineor yeast extract. These observations suggest that citrullinemay be catabolized during germination by means of OTC ratherthan via the energy-consuming urea cycle. (Received June 26, 1971; )     

Observations on the Biology of Fomes annosus, with Particular Reference to East Anglian Pine Plantations: II. Spore Production, Stump Infection, and Saprophytic Activity in Stumps

F. annosus produces conidia abundantly in culture but rarelyunder natural conditions. Sporophorea are formed on stumps anddying trees throughout the year provided that the humidity issufficiently high. Spore discharge in the plantations may occurat any time of year, but slowa down or ceases during very dryweather. It takes place at low temperatures, ceasing only whensporophores freeze. In the laboratory, F. annosus basidiospores germinate in relativehumidity exceeding 92 per cent. on freshly cut, unsterilizedpine wood. Viability is lost rapidly in light at temperaturesabove 15°C. Under humid conditions F. annosus spores will infect freshlycut pine stumps. There is evidence that spores of F. annosus washed down intosoil remain viable for at least a short period and that stumpscovered with soil are infected from this source. F. annosusspores can infect stumps for only a few weeks after felling,colonization after a longer interval probably beingprevdntedby competing fungi. In stumps inoculated with a mixed suspensionof F. annosus and Peniophora gigantea spores, Fomes at firstcolonized the wood but was soon replaced by P. gigantea. Otheraspects of competition are discussed. The incidence of natural infection in stumps and the factorsaffecting it are discussed Growth rates of F. annosus on malt agar and in lengths of pineroot are given. The fungus grows in stump roots at about 1 m.per year, and so closely approaches adjacent trees within ayear of thinning the plantation: In large stumps, F. annosusmay survive 15 or even 30 years after felling. Data are givenwhich suggest that the infective capacity of stumps containingF. annosus is greater in alkaline than in acid mils, while replacementby other fungi is slower. Competition of F. annosus with other fungi during colonizationof stumps is discussed. The parasite can grow along roots alreadyoccupied by certain fungi but not along roots containing others.The probable course of succession in stumps rotted by F. annousis described.     

Establishment of Isolated Root Cultures of Brassica Species and Regeneration from Cultured-root Segments of Brassica oleracea var. italica

Isolated root cultures which could be maintained over severalmonths by serial subculture were established from Brassica oleraceavar. italica cv. Green Comet F₁. A modified White's medium wasfound to be the best of several salt compositions tested. Theeffects on isolated root growth of the following were also examined;nutritional components, culture vessel type and closure, pHof the medium and auxin type and concentration. Using a mediumdevised for Green Comet, root cultures were established fromsix other B. oleracea, B. napus and B. campestris cultivars. It was possible to regenerate shoots from segments of culturedroots by incubation on agar-solidified media containing cytokininand auxin. The effects on regeneration of various auxins andcytokinins were investigated; the combination of Picloram withKN gave the highest frequency of shoot formation. It was demonstratedthat isolated roots retained their regenerative ability overa period of 5 months in culture. Brassica oleracea var. italica, Brassica napus, Brassica campestris, isolated root culture, shoot regeneration, organ culture     

氮、硅限制对赤潮藻扁面角毛藻休眠孢子形成的影响

休眠孢子的形成对于赤潮藻种群的保存、延续以及分布扩散等均具有重要的意义。通过单因子营养限制研究氮、硅对赤潮藻扁面角毛藻 (Chaetoceros compressus )休眠孢子形成的影响, 结果表明: 培养基中氮的初始浓度对休眠孢子的出现时间有一定影响。氮的初始浓度越低, 休眠孢子出现的时间越早; 反之, 氮的初始浓度越高, 休眠孢子出现的时间越晚。氮缺乏是硅藻形成休眠孢子的必需条件之一, 当培养基中氮含量低于10 mmol.L^-1时, 扁面角毛藻可以形成休眠孢子。氮缺乏诱发的休眠孢子的形成需要大量的硅, 当培养基中硅含量低于23 mmol.L^-1时, 即使氮缺乏, 扁面角毛藻也几乎不再继续形成休眠孢子。这说明硅藻休眠孢子的形成不仅受氮浓度的影响, 还与硅浓度有关。     

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     

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     

Culture of Mesophyll Protoplasts and Stem Segments of Antirrhinum majus (Snapdragon): Growth and Organization of Embryoids

Protoplasts isolated enzymatically from the leaves of Antirrhinummajus L. were cultured on a synthetic medium and their growthand development were followed in vitro. Cultured protoplastsincreased in size, regenerated cell walls, divided and formedsmall colonies and embryoids. Cell wall formation and cell divisionrequired both auxin and cytokinin in the medium. Isolated stemsegments of the same species, when cu1tured on a synthetic mediumwith an added auxin, yielded rapidly growing callus tissuesin which differentiation of embryoids occurred.     

Photoreversible absorption changes of guanidine-HCltreated phycocyanin and allophycocyanin isolated from the blue-green alga Tolypothrix tenuis

In the search for the photoreceptor in photocontrolled phycoerythrinformation, photoreversible absorption changes of chromoproteinsin vivo and in vitro were studied with the blue-green alga Tolypothrixtenuis. Neither intact cells nor crude extracts of soluble proteinsshowed any significant absorption changes which were reversiblyinduced by green and red light. However, the photoresponse wasobservable when the crude protein extracts were treated withthe chaotropic reagent guanidine-HCl (0.4 M, for 1 hr in thedark). Isolated phycocyanin and allophycocyanin also showedthe same photoresponse after the guanidine-HCl treatment. Thedifference spectrum (green minus red) of guanidine-HCl-treatedphycocyanin was almost identical with that shown by phycochromea of Bj?rn and Bj?rn (3), and the allophycocyanin showed thesame difference spectrum as those of phycochrome c of Bj?rnand Bj?rn and the photoreversible pigment isolated by Scheibe(7). Urea at a concentration higher than 1 M or alkaline incubation(pH 8.5) also showed the same effect. The results were interpretedas indicating that phycocyanin and allophycocyanin obtain theability for photoresponsiveness when their protein conformation,probably around the chromophore site, is modified. (Received October 30, 1978; )     

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     

Nanoscale Similarities in the Substructure of the Exines ofFagusPollen Grains andLycopodiumSpores

The exine substructure of an angiosperm,Fagus sylvatica(beech)pollen and a pteridophyte,Lycopodium clavatum(a club moss) sporewas investigated by scanning tunnelling microscopy. These pollenand spores, despite their distinct differences in structureand morphology on a micrometre scale, have very similar substructureon a nanometre scale. The substructure appears to consist ofa multi-helix, i.e. a helical chain in turn wound into a helixwith a self-similarity at smaller and smaller length scales.A simple vectorial form is proposed to describe quantitativelythe multi-helical substructure. Copyright 1998 Annals of BotanyCompany Fagus sylvatica,beech,Lycopodium clavatum, club moss, pollen, spores, exine substructure, scanning tunnelling microscopy.