瓦韦的“胎生现象”

蕨类植物的生活史中有2种植物体,即孢子体和配子体。其中配子体是能自养的、独立生存且有固定形态、发育模式、结构的植物体,它在蕨类植物生活史中占据较长的阶段．但常常不占优势．配子体世代通常是从孢予萌发开始,孢子萌发后发育为原叶体（即配子体）。存大多数蕨类植物中,     

蕨类植物孢子与种子植物花粉萌发的比较

蕨类植物孢子与种子植物花粉在有性生殖过程中都具有重要的作用。花粉作为种子植物的雄配子体, 通过萌发后极性生长的花粉管将精细胞送到胚囊完成受精作用。蕨类植物孢子作为配子体的原始细胞, 通过不对称的有丝分裂产生一大一小两个细胞, 小细胞萌发出极性生长的假根, 大细胞继续分裂发育为原叶体(配子体)。成熟的花粉和蕨类植物孢子都是代谢高度静止的细胞, 两者的萌发过程不仅都受到各种不同环境因子的影响, 而且在信号转导、极性建立和能量代谢等方面可能有着相似的调控机制。本文综述了蕨类植物孢子和种子植物花粉萌发过程的差异和保守性特征。     

蕨类植物孢子与种子植物花粉萌发的比较

蕨类植物孢子与种子植物花粉在有性生殖过程中都具有重要的作用。花粉作为种子植物的雄配子体,通过萌发后极性生长的花粉管将精细胞送到胚囊完成受精作用。蕨类植物孢子作为配子体的原始细胞,通过不对称的有丝分裂产生一大一小两个细胞,小细胞萌发出极性生长的假根,大细胞继续分裂发育为原叶体（配子体）。成熟的花粉和蕨类植物孢子都是代谢高度静止的细胞,两者的萌发过程不仅都受到各种不同环境因子的影响,而且在信号转导、极性建立和能量代谢等方面可能有着相似的调控机制。本文综述了蕨类植物孢子和种子植物花粉萌发过程的差异和保守性特征。     

蕨类植物孢子萌发及原叶体发育的观察

以腐叶土为培养基质,对21种蕨类植物进行了孢子萌发和原叶体发育的研究,结果表明：①不同时期播种的同种蕨类的孢子,发育出原叶体和幼孢子体所历经的时间长短不同;②孢子萌发和配子体生长发育的适宜温度约为15～24℃;⑨稀有蕨类的孢子萌发率低,而在野外能形成较大种群的蕨类的孢子萌发率高;④用GA3处理孢子可以促进萌发;⑤当原叶体上长出幼孢子体时,原叶体由大变小,由绿变黄,21种蕨类的原叶体都在幼孢子体上长出第3片叶时消失;⑥幼孢子体上长出的第1、2片叶在形态上与以后长出的叶不同;⑦孢子萌发需要光;⑧1片原叶体尽管有多个颈卵器,但仅发育出1株幼孢子体;⑨利用腐叶土进行蕨类孢子繁殖是一种经济实用的繁殖方法。     

蕨类植物孢子萌发影响因素的研究进展

蕨类植物经孢子萌发 ,产生配子体和形成孢子体 ,从而完成其世代交替的生活史 ;其中孢子萌发在整个生活周期中起着关键性的作用。简要介绍了近年来关于孢子萌发的研究进展。     

变异鳞毛蕨的孢子培养与配子体发育研究

应用无菌培养和常规泥土培养两种方法对变异鳞毛蕨(Dryopteris varia)孢子进行了比较研究,并在光学显微镜下观察了其配子体的发育过程.结果表明:蔗糖浓度为2%的1/2MS与MS培养基对孢子萌发时间和萌发率影响不大,但前者较适于孢子萌发,而后者则适于孢子体形成;在1/2MS培养基上,1%的蔗糖浓度比其它浓度更适宜于孢子的萌发.以菜园士为培养基质时,变异鳞毛蕨孢子的萌发时间短且萌发率高,但幼孢子体出现的时间明显晚于无菌培养.孢子萌发为书带蕨型,原叶体发育为三叉蕨型,符合鳞毛蕨属配子体发育的特征.     

观察蕨类生活史的好材料——铁线蕨

铁线蕨分布广泛,容易培养,是观察蕨类生活史的好材料。将经过低温处理（4℃）的铁线蕨成熟孢子接种到培养基上,在光照培养箱中培养45 d左右,孢子萌发后长成配子体,培养60 d左右,颈卵器内的受精卵萌发长出幼孢子体。将铁线蕨孢子接种到花盆内的土壤上,在室内培养2～3个月长成配子体,培养4～5个月长出幼孢子体。将培养基上的幼孢子体移栽到花盆土壤中可在室内长期培养,四季常青,孢子囊陆续分化、成熟。     

球子蕨孢子的无菌繁殖

以球子蕨成熟孢子为外植体,研究了不同激素及浓度对其孢子萌发、愈伤组织诱导、丛生芽分化及生根的影响。结果表明:孢子萌发最适培养基为1/2MS+2%蔗糖,20d后萌发率达55.7%;诱导愈伤组织的最适培养基为MS+0.5mg·L-1KT+0.5mg·L-12,4-D,诱导率达36%,愈伤组织为绿色颗粒状;颗粒状愈伤组织在不添加激素的MS培养基中即可生长出大量丛生芽,转化率可达49.3%;低浓度(0.2mg·L-1)的IAA可有效促进幼孢子体苗生根。     

银粉背蕨配子体及幼孢子体发育的研究

银粉背蕨是一种小型观赏蕨类植物,但目前我国对该蕨的研究还不够成熟。本文利用改良Knop's培养基和腐殖土培养银粉背蕨的孢子,观察其配子体及幼孢子体形态发育特征,并研究了其配子体发育的最适培养基pH值。研究结果显示：（1）银粉背蕨孢子黄褐色,具三裂缝,极面观三角圆形,赤道面观为近半圆形,孢子具网状纹饰;孢子萌发为书带蕨型;原叶体发育为水蕨型;颈卵器和精子器为薄囊蕨型;成熟原叶体为对称的心脏形,不具毛状体;上述特征为银粉背蕨孢子和配子体发育的稳定特征。（2）培养基pH值在7.0~9.0时随着碱性的增强,银粉背蕨孢子萌发和配子体生长发育速度逐渐增加。（3）利用腐殖土培养银粉背蕨孢子,7~8周可发育成幼叶,成苗率达90%,成苗健壮,根系发达,是扩繁银粉背蕨的适宜方式。本文为资源植物银粉背蕨人工繁殖和演化研究提供科学依据。     

光照、温度和pH值对小黑桫椤孢子萌发及早期配子体发育的影响

小黑桫椤(Alsophila metteniana)被列为我国国家二级保护植物。为探讨其种群数量下降原因, 作者采用无菌培养方法和显微观察技术, 在实验条件下研究了光照强度、光质、温度和pH值对小黑桫椤孢子萌发及早期配子体发育的影响。结果表明: 孢子萌发和配子体发育的最适光照强度为40–70 µmol;m^–2;s^–1, 全黑暗时孢子不萌发;白光、红光、黄光和蓝光下的萌发率分别为68.78%、65.66%、63.74%和7.51%; 白光和蓝光下配子体可以形成正常的心形原叶体, 红光和黄光下配子体发育一直处于丝状体阶段。孢子萌发和配子体发育需要在酸性土壤进行(pH值在3.7–6.7); 孢子萌发的适宜温度为20–30℃。从孢子接种到心形原叶体形成需要55 d左右。根据上述结果, 我们认为光照强度是小黑桫椤孢子萌发的必需条件, 光质是限制小黑桫椤孢子繁殖的重要原因; 光质、温度和pH值等环境因子的作用和配子体发育时间等是导致小黑桫椤种群数量日趋减少的主要原因。     

Effects of inorganic nitrogen sources on spore germination and gametophyte growth in Botrychium dissectum

Abstract. The effects of variations in nitrogen source upon spore germination and gametophyte growth of the eusporangiate fern Botrychium dissectum forma obliquum were investigated. Spore germination and early gametophyte growth were directly related to the oxidation level of the supplied nitrogen source. Nitrate and nitrite inhibited spore germination and at concentrations above 0.035 mol m^-3 prevented it entirely. Ammonium promoted germination well above the levels attained on media without nitrogen. Concentrations of ammonium greater than 0.035 mol m^-3 often resulted in germination above 90%. The growth of young gametophytes from spores was reduced on media without nitrogen or on media with high concentrations of nitrate. Ammonium stimulated the growth of both young and older gametophytes. However, older gametophytes were able to grow on media containing nitrate as the sole nitrogen source. We conclude that a reduced nitrogen source is necessary for spore germination and early growth of Botrychium gametophytes. This requirement has several ecological implications which may be related to the distribution of these ferns and the establishment of mycorrhizal associations.     

Gametophyte development and reproduction of the Asian fern Polystichum polyblepharum (Roem. ex Kunze) C. Presl (Dryopteridaceae,Polypodiopsida)

Abstract

The gametophytic generation of Polystichum polyblepharum (Dryopteridaceae), including spore germination, morphological development of the gametophytes, major vegetative features and reproduction strategies, was studied. Spore germination was of the Vittaria model and the developmental pattern was of the Aspidium model. Adult gametophytes were cordate and hairy, with unicellular hairs located at the margins and at the prothallus surface. The marginal ones were secretory. The gametophytes produced archegonia located in the central area between the notch and the rhizoids, but antheridia were never detected. Archegonia were of the normal type described for leptosporangiate ferns. Apogamous sporophytes appeared from a cellular outgrowth developed just under the apical notch. Initially, the outgrowth appeared completely surrounded by glandular hairs and scales, which persisted throughout the subsequent stages of leaf development.     

Gametophytic phase of Alsophila odonelliana (Cyatheaceae)

The gametophytic morphology and development of Alsophila odonelliana (Alston) Lehnert, have been studied through in vitro cultures. This species grows in southern Bolivia and northwestern Argentina. The spores are uniform in structure, but not in size; a certain percentage being smaller than the average. 16 spores per sporangium were found. The germination is of the Cyathea type. It was found that spores stored at 4°C can maintain their viability for over two years. The maximum value of germination depends on spore age. The filamentous gametophytes are 4–16 cells long. Young gametophytes have 1–2 branches that give rise to new gametophytes. Male, female, bisexual and neuter gametophytes were found. Propagules were frequently found in neuter gametophytes, and female and bisexual gametophytes were found to have chlorophyll containing scales. The antheridia are made up of five cells and produce non‐viable spermatozoids. The archegonia have necks formed by four columns with four cells each. Most of the gametophytic phase is documented with photomicrographs.     

Prothallia in nine species of Callipteris and its comparison with other genera of the Woodsiaceae family

The development of the prothallia in nine species of Callipteris Bory (Woodsiaceae), four species of Diplazium, the genus from which Callipteris has been segregated, and one species of Dryoathyrium are studied in this paper. The data obtained are compared with the development of the prothallia of several other genera of Woodsiaceae. The main difference between Callipteris and the other genera of Woodsiaceae was that the antheridia dehiscence of Callipteris, occurs by an opercular cell and whereas some of Diplazium and other Woodsiaceae antheridia dehiscence occurs by a lateral or apical pore. The presence of antheridiogens is suspected on the basis of small ameristic male gametophytes in the cultures. Spore germination in Callipteris is Vittaria-type, prothallial development corresponds to Adiantum-type.     

孢子大小和培养基对水蕨孢子萌发及配子体性别分化的影响

利用MS培养基、改良Knop’s培养基、自来水和蒸馏水分别培养水蕨中等大小孢子,同时利用改良Knop’s培养基培养不同大小的水蕨孢子,观察记录不同条件下水蕨孢子萌发和性别分化情况。实验表明,二级孢子（赤道轴120～140μm）萌发率最高;一级孢子（赤道轴〉140μm）萌发最有利于使水蕨发育为两性配子体,三级孢子（赤道轴〈120μm）萌发最有利于使水蕨发育为雄配子体;MS培养基和改良Knop’s培养基相对于自来水和蒸馏水有利于水蕨孢子萌发;各培养基中水蕨两性配子体比率排序是MS培养基〉改良Knop’s培养基〉自来水〉蒸馏水,而雄配子体比率排序与之相反。此结果为水蕨的引种保护、人工繁育和分子生物学研究提供理论依据。     

2种培养基下紫萁配子体发育及孢子体形成的研究

采用光镜技术对不同培养基下紫萁配子体发育和孢子体形成进行了研究.结果表明:(1)紫萁孢子绿色,四面体形,具三裂缝,孢子两极萌发分别产生假根和原叶体细胞,原叶体细胞形成球形体,球形体产生分生细胞发育为片状体和原叶体.(2)原叶体可为雄性、雌性或两性;雄原叶体较小,其两翼基部产生多数精子器;雌原叶体大,具有明显的中肋,在中...     

岩蕨属植物配子体发育初报

本文为岩蕨属植物心岩蕨、岩蕨和耳羽岩蕨配子体个体发育和比较形态学初步研究。报道了用无机琼脂培养基由孢子培养配子体的方法。由孢子萌发到配子体成熟分四个时期:萌发期,原丝体发育期,过渡期和原叶体发育期。大多数原丝体发育到七个细胞,与顶端细胞相隔的原丝体细胞开始胞间细胞纵向分裂,进入过渡期。同时顶端细胞的横分裂受到抑制,直至原叶体顶端细胞形成开始原叶体发育期。岩蕨成熟配子体精子器盖细胞不分裂,耳羽岩蕨分裂为一个圆形细胞和一个镰刀形细胞,而心岩蕨两种情况兼而有之,配子体比较形态特征支持心岩蕨可能是以岩蕨和耳羽岩蕨为双亲的异源双二倍体的假设[5]。     

乌蕨配子体发育及卵发生的显微观察

采用光学显微镜对乌蕨的配子体发育及卵发生的过程进行了研究,以阐明蕨类植物颈卵器发育特征,为揭示蕨类植物有性生殖机制以及鳞始蕨科的演化提供依据。结果表明:(1)乌蕨孢子黄褐色,具单裂缝,表面平滑或呈疣状纹饰;孢子接种12d萌发,萌发类型为书带蕨型,原叶体发育类型为铁线蕨型。(2)半薄切片观察表明,乌蕨颈卵器产生于原叶体生长点下方的表面细胞,即颈卵器原始细胞,该细胞经过两次分裂形成纵向3层细胞,最上层细胞发育为颈卵器的颈部壁细胞,中间层细胞即初生细胞再经过两次不等分裂产生颈沟细胞、腹沟细胞和卵细胞,此三细胞最初紧密贴合,随着颈卵器的发育,卵细胞与腹沟细胞间从两侧向中间产生分离腔,且腹沟细胞与颈沟细胞开始退化;分离腔逐渐向中间扩大,直至出现孔状结构,即受精孔;颈卵器发育后期,在卵细胞上表面形成染色较深的卵膜,颈沟细胞与腹沟细胞退化成絮状物。     

Cytokinins induce photomorphogenic development in dark-grown gametophytes of Ceratopteris richardii

The cytokinins benzylaminopurine, kinetin and isopentenyladenine induce photomorphogenesis in dark-grown gametophytes of the fern Ceratopteris richardii. At sub-nanomolar concentrations each altered the rate and pattern of cell division, elongation and differentiation, mimicking aspects of the light-mediated transition from filamentous to prothallial growth. Untreated dark-grown gametophytes grow as narrow, elongate, asexual filaments with an apical meristem. Cytokinin treatments as low as 10(-12) M reduced the length-to-width ratio through decreased cell elongation, increased periclinal cell division and induced the formation of rhizoid initials in the cells immediately below the apical meristem. Higher concentrations (10(-9)-10(-8) M) induced conversion of the meristem from apical to notch morphology. Cytokinins induced both red- and blue-light-mediated photomorphogenic events, suggesting stimulation of both phytochrome and cryptochrome signaling; however, cytokinin treatment only partially substituted for light in that it did not induce hermaphroditic sexual development or spore germination in the dark. Additionally, cytokinins did not increase chlorophyll synthesis in dark-grown gametophytes, which unlike angiosperms are able to produce mature chloroplasts in the dark. Cytokinin treatment had only slight effects on light-grown gametophytes. These results suggest evolutionary conservation between angiosperms and pteridophytes in the role of cytokinins in regulating photomorphogenesis.     

<Emphasis Type="Italic">In vitro</Emphasis> culture of <Emphasis Type="Italic">Drynaria fortunei</Emphasis>, a fern species source of Chinese medicine “Gu-Sui-Bu”

This study reports spore germination, early gametophyte development and change in the reproductive phase of Drynaria fortunei, a medicinal fern, in response to changes in pH and light spectra. Germination of D. fortunei spores occurred on a wide range of pH from 3.7 to 9.7. The highest germination (63.3%) occurred on ½ strength Murashige and Skoog basal medium supplemented with 2% sucrose at pH 7.7 under white light condition. Among the different light spectra tested, red, far-red, blue, and white light resulted in 71.3, 42.3, 52.7, and 71.0% spore germination, respectively. There were no morphological differences among gametophytes grown under white and blue light. Elongated or filamentous but multiseriate gametophytes developed under red light, whereas under far-red light gametophytes grew as uniseriate filaments consisting of mostly elongated cells. Different light spectra influenced development of antheridia and archegonia in the gametophytes. Gametophytes gave rise to new gametophytes and developed antheridia and archegonia after they were transferred to culture flasks. After these gametophytes were transferred to plastic tray cells with potting mix of tree fern trunk fiber mix (TFTF mix) and peatmoss the highest number of sporophytes was found. Sporophytes grown in pots developed rhizomes.