Spore Germination and Gametophyte Development in Three Species of Asplenium

Laboratory and field experiments involving Asplenium ruta-murariaL., Asplenium trichomanes L. subsp. quadrivalens D.E. Meyeremend. Lovis and Asplenium scolopendrium L. [= Phyllitis scolopendrium(L.) Newm.] revealed differences in their temperature requirementsfor germination and in their sexual development on soil. Thegermination responses of A. trichomanes and A. scolopendriumto culture temperatures of 10, 15, 20 and 25 °C were verysimilar and all spores were able to germinate at 10 °C.Spores of A. ruta-muraria differed in that germination was slowerat 15-25 °C and very much delayed, or even inhibited, at10 °C. Both laboratory and field cultures of A. trichomanesand A. scolopendrium produced male, female and bisexual gametophyteswhereas those of A. ruta-muraria produced only males and bisexuals.The ecological significance of these differences is discussed.Copyright1994, 1999 Academic Press Fern, Asplenium ruta-muraria, Asplenium trichomanes, Asplenium scolopendrium, Phyllitis scolopendrium, spore germination, gametophyte, reproductive biology, temperature effects, field experiments     

The Effect of Gabaculine on Germination and Gametophyte Morphogenesis of Anemia phyllitidis L.Sw.

Gabaculine, applied to germinating spores of the fern Anemiaphyllitidis in concentrations between 10^–4 M and 10^–6M inhibits chlorophyll synthesis together with considerablesimplification of chloroplast ultrastructure. Though gabaculinereduced phytochrome-induced morphogenetic effects (cell shape,inhibition of hormonal antheridium induction), the rate of redlight-induced spore germination, however, has not been affectedby the inhibitor. This indicates significant differences betweenthe two types of photomorphogenetic reactions regarding theirdependency on phytochrome homeostasis. (Received April 21, 1986; Accepted October 22, 1986)     

Aphidicolin Inhibition of DNA Synthesis and Germination in Spores of Anemia phyllitidis L. Sw

Aphidicolin inhibits DNA synthesis and nuclear division in spores of Anemia phyllitidis. In spite of blocked DNA replication, spores germinate under continuous dark conditions, if induced by addition of 5 × 10⁻⁵ grams per milliliter gibberellic acid. Differentiation of aphidicolin-treated prothallia indicate the existence of a prepattern in the dry spore which is realized independent of cell division during early events of spore germination.     

Partial characterization of an antheridiogen of Anemia mexicana: Comparison with the antheridiogen of A. phyllitidis

An antheridiogen of Anemia mexicana Klotzsch has been partially characterized by combined gas chromatography-mass spectrometry and gas chromatography-Fourier transform/infra-red spectrometry. It is a C₁₉-gibberellin(GA)-like compound with one carboxyl group, an exocyclic methylene group and a lactone ring. It also has one hydroxyl-group and one double-bond equivalent which has not been determined. On the basis of its mass spectrum, it is not identical to previously identified monohydroxy GAs with one ring double bond such as GA₅, GA₇, GA₃₁ and GA₆₂. By direct comparison of mass spectra, the antheridiogen of A. mexicana was also determined to be different from the antheridiogens of Anemia phyllitidis (L.) Swartz, Anemia hirsuta (L.) Swartz and Lygodium japonicum (Thunb.) Sw.Abbreviations GA(s) gibberellin(s) - GA_a gibberellin A_n - GC-FT/IR combined gas chromatography-Fourier transform/infra-red spectrometry - GC-MS combined gas chromatography-mass spectrometry - IR intra-red spectrometry - KRI Kovats Retention Index - m/z mass/charge - TLC thin-layer chromatography - TMSi trimethylsilyl     

Effects of Gibberellins and Their Methyl Esters on Dark Germination and Antheridium Formation in Lygodium japonicum and Anemia phyllitidis

The effects of GA₃, GA₄ and GA₉ and their methyl esters on darkspore germination and antheridium formation of the ferns Lygodiumjaponicum and Anemia phyllitidis were investigated. Althoughall induced both germination and antheridium formation in Lygodium,only the gibberellins induced these effects inAnemia. (Received August 28, 1986; Revision received November 14, 1986. )     

Aminooxyacetic acid inhibits antheridiogenesis and development of Anemia phyllitidis gametophytes

Cytomorphological studies of the development of young fern gametophytes (Anemia phyllitidis) have been used to investigate combined effects of gibberellic acid and ethylene on male sex expression. ACC (the key by-product in ethylene biosynthesis pathway) was found to exert a synergetic effect on the gibberellic acid-induced antheridia formation, and this phenomenon could be related with the specific stimulation of cell growth and activity of their differentiation. To complete and verify those observations male sex expression in the fern gametophytes treated with ACC-biosynthesis inhibitor was reinvestigated. Aminooxyacetic acid (AOA) restrained antheridia formation via inhibition of cell divisions. AOA influenced the arrangement and flexibility of cellulose microfibrils in the antheridial zone cells, thus affecting cell expansion. On the other hand, the level of DNA synthesis was not reduced. Transient increase in the number of S-phase cells, followed by the accumulation of G2-phase cells led to the enhancement of cell polyploidization. All these findings correspond with the previous observations and support participation of ethylene in gibberellic acid-induced male sex expression in ferns.Abbreviations AOA Aminooxyacetic acid - CPA Cell profile area - GA Gibberellin - GA₃ Gibberellic acid     

Microsporogenesis, Pollination, Pollen Germination and Male Gametophyte Development in Taxus brevifolia

Taxus brevifolia(Nutt.), commonly known as Pacific or westernyew, is a conifer native to the Pacific northwest of North America.Contrary to other Taxus species, T. brevifolia staminate strobiliare usually located on 2-year-old foliage although they mayoccur on foliage from 1 to 5-years-old. This delayed staminatestrobilus development may be an adaptation to the low lightenvironment where T. brevifolia grows. Microsporogenesis occurredin the autumn preceding pollination. Successive divisions producedisobilateral tetrads visible as early as mid-October. Over-winteringstaminate strobili usually contained separate microspores. In1996 to 1999, pollination occurred in March and April in twonatural forest sites on southern Vancouver Island, British Columbia,Canada. The low amounts of airborne pollen and prolonged pollinationperiod indicated low pollination success within T. brevifolia.Female receptivity was measured by the presence of a pollinationdrop. Protandry up to 18 d was observed. In vitro pollen germinationwas moderate to good, ranging from 65 to 88% depending on thetree and year. DAPI fluorescence staining showed successfulmale gametophyte development in vitro. The microspore dividedforming a tube nucleus and generative cell within 3 d of culture.The generative cell then divided forming a sterile nucleus andspermatogenous nucleus after 17 d. The spermatogenous nucleusacquired a cell wall then divided forming two equal sperm after24 d. Copyright 2000 Annals of Botany Company Taxus brevifolia, Pacific yew, microsporogenesis, pollination, pollen germination, male gametophyte development     

苔藓植物孢子萌发与原丝体发育研究进展

孢子萌发与原丝体发育对于研究苔藓植物以及其他植物类群的系统发育与系统演化有着十分重要的作用。本文综述苔藓植物孢子萌发类型、原丝体发育特征以及环境影响因子等,还介绍了20世纪90年代以来该领域研究的新进展,如人们以苔藓植物原丝体为实验材料进一步揭示Ca2 ．CAM信号系统、植物激素、光信号系统等在植物体内的作用机制。     

Ethylene is Involved in the Control of Male Gametophyte Development and Germination in Petunia

The time courses of 1-aminocyclopropane-1-carboxylic acid (ACC) content and ethylene production in developing anthers of petunia fertile and sterile lines and the effects of exogenously applied ethylene and an inhibitor of ethylene action, 2,5-norbornadiene (NBD), on male gametophyte development and germination were investigated. Fertile male gametophyte development was accompanied by two peaks of ethylene production by anther tissues. The first peak occurred during microspore development simultaneously with degeneration of both tapetal tissues and middle layers of the anther wall. The second peak coincided with maturation and dispersal of pollen grains. The mature pollen is characterized by a high ACC content (up to 300 nmol/g). Exogenously applied ethylene (1–100 ppm) induced degradation of gametophytic generation at the meiosis stage. NBD completely inhibited anther development at the early stages of its development and delayed anther dehiscence. In anther tissues of the petunia sterile line, tenfold higher ethylene production was observed at the meiosis stage compared to that in fertile male gametophytes and this correlated with degeneration of both microsporocytes and tapetal tissues. In vitro male gametophyte germination was accompanied by an increase of ethylene production, whereas NBD completely blocked male gametophyte germination. These results suggest that ethylene is an important factor in male gametophyte development and germination.     

东北刺人参种子萌发影响因子的研究

东北刺人参(Oplopanax elatus Nakai)种子透水性良好,休眠后萌发不受其影响.种皮和胚乳的水提取物中存在萌发抑制物质,胚乳中提取物对白菜种子萌发的抑制效果比种皮更明显.种子自然脱落时胚尚未分化完全,处于心形胚阶段.种子需要先温暖层积以完成胚的分化与生长,然后转入低温层积完成生理后熟.同批种子胚的发育不完全同步,变温层积处理7个月有极少数种子萌发,连续变温层积处理17个月大部分种子萌发.不同年份受气候条件影响,种子产量和发芽率差异较大.种子耐贮性较强,贮藏2年的种子生活力变化不大,仍具有较高的萌发潜力.     

Fine Structure and Spore Germination in Fusarium culmorum

The fine structure of the macroconidium of Fusarium culmorum(W. G. Smith) Sacc. is described. The presence of a mucilaginouscoat around the conidium and its expansion during germinationare confirmed. Studies of germinating conidia have shown changesin the numbers of organelles. The germ tube is shown to be formedfrom an entirely new wall laid down in the conidium, and theemergence of the germ tube is brought about by lysis of theoriginal condial wall.     

Ribosomal Competence and Spore Germination in Fusarium solani

Extracts prepared from macroconidia of Fusarium solani f. sp. phaseoli are capable, under defined conditions, of incorporating phenylalanine into polypeptide with exogenous polyuridylic acid as messenger. Extracts from ungerminated and germinated spores have approximately the same activity. With endogenous template, leucine incorporation occurs, but in this reaction extracts from germinated spores have about 10 times more activity than do those from ungerminated spores. It is suggested that the low rate in ungerminated spores is attributable to a relative deficiency in the number of ribosomes which are organized into polysomes.     

The polyadenylic sequences in the ribonucleic acid of the fern Anemia phyllitidis

The vegetative prothalli (1–3 weeks old) of Anemia were incubated for 24 h in [¹⁴C]adenine. The RNA was phenol extracted from whole cells and the poly (A) sequences were isolated by nuclease digestion followed by poly (U)-sepharose chromatography. About 2–3% of the total radioactivity was retained on the column. The base composition of the nuclease resistant RNA was: C, 1.4; G, 3.6; A, 93.3; and U, 1.7. It is concluded that Anemia RNA contains poly adenylate sequences.Part of a post-doctoral work. Fellowship awarded by Alexander von Humboldt-Stiftung, Federal Republic of Germany     

Effects of Calcium and Calmodulin on Spore Germination and Appressorium Development in Colletotrichum trifolii

Spore germination and appressorium formation are important steps in the process of fungal development and pathogenesis. These prepenetration events, which begin with spore attachment and culminate with appressorium maturation, a common scheme for many pathogenic fungi, are prerequisites for penetration of host external barriers and subsequent colonization. Conditions for in vitro spore germination and appressorium development in Colletotrichum trifolii are described. In addition, effects of Ca(sup2+) and calmodulin on these processes have been examined. Results indicate that, as for other pathogenic fungi, appressorium development is induced on a hard surface. The data suggest that disturbance of calcium homeostasis, by ethylene-bis(oxy-ethylenenitrolo)tetraacetic acid (EGTA) or calcium channel blockers, impairs appressorium development. Moreover, calmodulin inhibitors affect both germination and differentiation, implying that the Ca(sup2+)/calmodulin signal transduction pathway is important in the early development of C. trifolii on the plant host surface.     

五种藓类植物的孢子萌发与原丝体发育

本文对中华缩叶藓(Ptychomitrium sinense)、狭叶缩叶藓(P.linearifolium)、威氏缩叶藓(P.wilsonii)、葫芦藓(Funaria hygrometrica)和立碗藓(Physcomitrium sphaericum)5种国产藓类植物的孢子萌发和原丝体发育进行研究,结果表明不同藓类孢子萌发和原丝体发育类型不同,孢子萌发和原丝体发育方式与藓类植物的生态环境有关.     

Changes in Microsporum gypseum Mycelial Wall and Spore Coat Glycoproteins During Sporulation and Spore Germination

Ethylenediamine-soluble glycoproteins were extracted from isolated Microsporum gypseum hyphal walls during sporulation and from spore coats before and after germination. This study was carried out to identify a sporulation-specific cell wall protein that possibly served as a substrate for the alkaline protease which initiated the macroconidial germination of this fungus. Analyses revealed that water-insoluble glycoprotein accounted for 10% of the ungerminated spore coat but only for 4 to 5% of the mycelial wall dry weight. This fraction was modified in its amino acid composition during sporulation, and it decreased in protein content during spore germination. Water-soluble glycoprotein, which accounted for approximately 3 to 3.5% of either the spore coat or mycelial wall dry weight, was of similar amino acid composition from both sources and did not decrease in protein content upon spore germination. The water-insoluble glycoprotein was found to be rich in leucine, aspartic acid, glycine, glutamic acid, and phenylalanine residues. The water-soluble glycoprotein was rich in proline, threonine, glycine, serine, glutamic acid, and alanine.     

Effects of 5-bromo-deoxyuridine on chloroplast structure in gametophytes of Anemia phyllitidis L. Sw.

Application of 5-bromo-2-deoxyuridine causes servere changes in the ultrastructure of chloroplasts. These modifications include an increase of thylakoid layers ("giant"-grana), coiling of thylakoids, and lastly vacuolization of the entire membrane system of the chloroplast. Such observations can be correlated with types of membrane aberrations reported for natural mutants.