卡德丽亚兰种子非共生萌发及萌发过程中原球茎发育的细胞学研究

对卡德丽亚兰种子非共生萌发条件及萌发过程中原球茎发育进行了研究。结果表明,低离子浓度培养基(KC、RE)利于卡德丽亚兰种子萌发;适宜种类和浓度的激素(1.0mg/LBA和0.1mg/LNAA或1.0mg/LKT和0.1mg/LNAA)对种子萌发有良好的促进作用。细胞学研究表明:卡德丽亚兰种子萌发过程的本质是未分化胚细胞团通过细胞的不断分裂形成原球茎,原球茎出现极性,随之分化形成芽端分生区,最终形成实生苗。     

盾叶薯蓣类原球茎发育的形态解剖学观察

为探讨盾叶薯蓣类原球茎形态建成的发育机理及植株移栽成活率高的原因,对盾叶薯蓣离体培养条件下形成类原球茎的形态发生过程进行形态学和石蜡切片组织学观察,并与不定芽的发生进行比较。结果表明：类原球茎是由愈伤组织中致密的卵圆形胚性细胞团分化出芽原基和鳞片叶,随后出现初生增厚分生组织和原形成层（维管束原）,其类原球茎形态建成。不定根的发生为内起源,其维管组织与类原球茎的维管组织相连接,故移栽成活率高。而不定芽为愈伤组织表面的胚性细胞分裂产生的分生细胞团分化而来,其不定根通常发生在茎基部形成的愈伤组织表面,故不易成活。     

水稻愈伤组织内部胚性细胞的形成及发育

发育成胚状体的水稻愈伤组织表面胚性细胞, 在继代过程中被非胚性细胞旺盛的分裂所包围, 渐渐形成内部胚性细胞。其形态结构与表面胚性细胞相同, 但周围缺乏表面细胞下面的一层至几层含丰富的淀粉粒的细胞。内部胚性细胞形成团后先在以处形成突起, 产生根冠原, 逐渐形成根而突出愈伤组织。内部胚性细胞可向四周同时但不同步形成根冠原。未见芽或胚状体从内部胚性细胞产生。推测胚性愈伤组织失支胚胎发生能力及分化能力可能部分地与胚性细胞部分裂或分裂不旺盛、而非胚性细胞分裂旺盛从而使胚性细胞被包围、稀释有关。     

兔眼蓝莓离体叶片再生组织细胞学观察

离体叶片再生是兔眼蓝莓离体快繁和遗传转化的重要途径。为了探明兔眼蓝莓离体叶片再生途径,以兔眼蓝莓杰兔品种的试管苗叶片为外植体,对离体叶片再生途径进行细胞学观察。结果表明,离体叶片不定芽在30 d内基本完成其发生、发育和形成的全过程。离体叶片以直接再生途径发生不定芽,且属于多起源,其分生组织起源于离体叶片切口附近与维管束相邻的上表皮细胞、维管组织薄壁细胞及周围薄壁细胞,通过细胞分裂和分化形成分生细胞团,直接形成芽,再发育成苗。此外,兔眼蓝莓离体叶片不定芽的形成具有特定的时空特性,多个不定芽先后在离体叶片上形成单芽或丛生芽。     

细枝木麻黄离体培养过程中愈伤组织和再生芽的细胞组织学观察

为探讨细枝木麻黄(Casuarina cunninghamianaMiq.)愈伤组织分化过程的细胞组织学,对离体培养条件下的愈伤组织进行扫描电子显微镜和石蜡切片观察,分析愈伤组织的细胞分裂、分化以及芽再生的发生过程。结果表明,新鲜外植体培养于愈伤组织诱导培养基上,伤口处的薄壁细胞开始脱分化,培养1周后形成明显的愈伤组织;继续培养2周后,胚性愈伤组织形成,且表层细胞启动分化形成芽原基;培养4周,可肉眼观察到胚性芽原基,数量增多并逐渐分化形成不定芽;培养至第6周,生成不定芽,并大量增殖和分化。因此,细枝木麻黄是通过愈伤组织分化形成胚状体的途径进行植株再生的,为建立细枝木麻黄组织培养高效再生体系提供了理论依据。     

屋顶长生草叶的解剖结构及其离体培养形态发生的研究

对屋顶长生草叶的解剖结构及其在离体培养条件下形态发生过程进行了研究。结果表明,屋顶长生草的叶具有肉质旱生植物叶的特点,表皮细胞外有角质层,叶有较密的腺毛分布,气孔器由两个肾形的保卫细胞和两个镰刀形的护卫细胞组成;叶肉细胞没有栅栏组织与海绵组织之分,细胞比较大,有贮水作用;维管束平行排列,导管和筛管分子都很小,为一圈维管束鞘所包围。屋顶长生草叶片离体培养形态发生途径主要有两种:一种是由外植体直接产生不定芽(器官型)途径;另一种是叶肉细胞脱分化成胚性细胞,经胚性细胞团形成愈伤组织,再分化产生芽、根等器官(器官发生型),芽分化为内起源。     

黑节草未成熟种子的形态发育及其在离体培养时的表现

黑节草(Dendrobium candidum Wall ex Lind.)2—6个月种龄的胚均处于球形胚阶段,不同种龄的胚在体积大小、胚细胞数目、胚细胞内的淀粉粒含量和超微结构上有差异。在离体培养条件下黑节草种子萌发率可达95％,种子萌发后形成原球茎,原球茎可以直接发育形成幼苗,又可以由原球茎产生大量愈伤组织,由愈伤组织再分化发育成幼苗。种子萌发过程中,胚顶端分生组织细胞的淀粉逐渐消耗,淀粉的变化与分生组织和子叶的形成有明显的相关性。     

香根草体细胞胚胎发生的细胞学特点与形成条件

香根草是一种优良的生态环境治理植物,但也存在着一些局限性。为了对香根草进行遗传改良,选育出性状更优、抗性更强的新品种,开展了香根草离体培养研究。离体培养采用了两种外植体,一是带腋芽的节,二是由器官发生方式所产生的无菌不定芽。基本培养基为MS,根据不同的目的附加不同种类或配比的生长素与细胞分裂素。观察到香根草的外植体的离体发育途径,有器官发生和体细胞胚胎发生两种,依培养基中所含细胞分裂素或生长素的种类和用量不同而异。结果表明,香根草的这两种离体发育途径的植株再生能力均可以长期保持。细胞学的研究显示,香根草离体发育的启动可在外植体的表皮细胞或薄壁细胞中进行,这些细胞逐渐发育成为胚性细胞。胚性细胞分裂活跃,经二细胞、四细胞而发育成为多细胞的胚性细胞团。由显微观察可知,香根草的体细胞胚胎发生是单细胞起源的,成熟的体细胞胚具有单子叶植物典型的胚胎结构。在分化培养基的作用下,体细胞胚组织上所有的胚状体可以出芽而形成再生植株。所建立的香根草体细胞胚胎发生的植株再生体系,完全适用于遗传转化等生物工程方法对离体培养要求。此外,还观察到一些一般只有在双子叶植物才出现的鱼雷形体细胞胚,这是体细胞胚胎发生中的异常现象。认为这种异常胚是离体培养所引起的。     

狗蔷薇类原球茎发育过程的显微观察

对狗蔷薇类原球茎发育进行显微观察的结果表明：类原球茎发育过程中外部形态发生了明显的变化;毛状不定根及其产生的类原球茎均具备根的结构特点;类原球茎由毛状不定根中维管柱顶端外围的中柱鞘薄壁细胞发育而来,是包括胚性细胞和薄壁细胞在内的囊腔状结构的复合组织,胚性细胞在类原球茎中的发育经历了原胚、球形胚、心形胚和鱼雷胚阶段,并且与周围的细胞存在明显的生理隔离;类原球茎具有明显的极性,并且可以重复发生形成次类原球茎。     

亚洲百合花丝离体培养器官形成的细胞形态学研究

对亚洲百合的花丝进行离体培养,并利用常规石蜡制片技术对诱导效果最好的材料进行细胞形态学观察,研究花丝在离体培养过程中器官形成的细胞形态学变化。结果表明:花丝在MS+BA0.5 mg/L+NAA0.5 mg/L的培养基上诱导效果最好。离体培养后其形态学下端切口内方的1～3层细胞首先启动脱分化,然后是内方的10～12层细胞,而其他部位的细胞自始至终未启动脱分化。亚洲百合的再生方式为器官发生型,器官通过胚性愈伤组织间接产生,在胚性愈伤组织团表面附近形成芽原基,或在胚性愈伤组织团内部形成根原基,有时同时分别在内、外形成根原基和芽原基后再通过维管组织连接成完整的植株。本研究为亚洲百合的人工调控提供基础理论依据。     

Ultrastructural characteristics of the parenchymatous cells in breast cancer

Electron microscopy was used to examine ultrastructure of parenchymatous cells of lobular mammary carcinoma and preservation of an ability of these cells to organ specificity. Ultrastructural characteristics of the cells of intact mammary gland lobules and parenchymatous cells of infiltrative carcinoma were studied and compared. It was shown that lobular mammary carcinoma has dissimilar cellular composition. It is represented by the cells with ultrastructural features characteristic for the three cell types occurring in the intact mammary gland (secretory epithelium, myoepithelium and cambial cells). As regards ultrastructure, parenchymatous cells of lobular mammary carcinoma, like the cells of the normal lobule, are at varying levels of differentiation and in diverse phases of the functional status.     

An intact microtubule cytoskeleton is not necessary for interfacial matrix formation in orchid protocorm mycorrhizas

 This paper reports the changes that occur in the microtubule cytoskeleton of cells of orchid protocorms during infection by a compatible mycorrhizal fungus. In cells of protocorms uninfected by a mycorrhizal fungus, microtubules occurred in regular arrays. In contrast, the cells of orchid protocorms with established mycorrhizas appeared to contain irregularly arranged microtubules. Double labelling with anti-β-tubulin and rhodamine-labelled wheat-germ agglutinin demonstrated that these irregularly arranged microtubules occurred only inside fungal hyphae and that microtubules were absent from host cells containing mycorrhizal fungi. Microtubule depolymerisation was shown to occur at the early stages of fungal infection. There was neither loss of nor obvious organisational change in microtubules in cells adjacent to others containing fungal hyphae. Electron microscopy confirmed the presence of an interfacial matrix between the host plasma membrane and the hyphal wall. The loss of microtubules from cells infected by mycorrhizal fungi suggests that an intact host microtubule cytoskeleton is not necessary for the formation of the interfacial matrix in mycorrhizas of orchid protocorms. Accepted: 9 November 1995     

Atypical foliar anatomy related to Kranz syndrome in Paspalum inaequivalve and Paspalum microstachyum (Poaceae: Panicoideae: Paniceae)

Paspalum L. is a large and complex genus, enclosing more than 300 species, whose boundaries and infrageneric classification are still being studied. Recent phylogenetic analyses suggest that Paspalum inaequivalve Raddi and Paspalum microstachyum J. Presl, from the Inaequivalvia informal group, should be excluded from Paspalum. Focused on the unclear taxonomic position of P. inaequivalve and P. microstachyum, their leaf anatomy was studied, and some atypical features related to C₄ photosynthesis were found. This atypical Kranz syndrome is the aim of this research. Transverse leaf blade sections from fresh and herbarium material of P. inaequivalve were studied by light, fluorescence, and transmission microscopy. Additionally, sheaths and culms of P. inaequivalve and leaf blades of P. microstachyum were observed by light microscopy. δ¹³C isotope discrimination was determinated for P. inaequivalve. We compared our results with available anatomical data from related taxa. As well as typical mesophyll cells (PCA) and mestome sheath cells (PCR), a third type of cells, here called ‘globose parenchymatous cells’, was observed in leaf blades of P. inaequivalve and P. microstachyum. These cells are placed externally to the mestome sheaths of the first and second vascular bundles, they have thin walls, with no developed suberine lamella, few chloroplasts with 1–2 starch grains, thylakoids not organized in grana, and a large central vacuole. The globose parenchymatous cells represent a novel trait in P. inaequivalve and P. microstachyum, further supporting the close relation between both species and their exclusion from the genus Paspalum. This atypical Kranz syndrome has not been described in Paspalum before, but the globose parenchymatous cells here described resemble the distinct cells considered as remnants of the outer parenchymatous sheath described for Anthaenantiopsis, some sections of Panicum L., and Chaetium Nees, providing possible taxonomic significance.     

鹤顶兰种子萌发及原球茎增殖培养研究

以鹤顶兰成熟蒴果的种子为实验材料,研究影响种子非共生萌发的因素和种胚发育途径,并采用正交设计研究了原球茎增殖的影响因素。结果表明:冷藏影响种子的活力且其萌发率随冷藏时间延长而降低;0.5%NaClO溶液浸泡种子可提高萌发率,缩短初始萌发时间;种胚发育途径为种胚转绿后从种子侧面突破种皮而形成原球茎,随后分化出具根芽结构的完整植株;6-BA对原球茎增殖作用显著,原球茎增殖的最适培养基为1/2MS+3.0mg/L6-BA+1.0mg/L KT+1.0mg/L NAA,增殖倍数为6.67。     

The structure and development of the haustorium in parasitic Scrophulariaceae*

The structure and development of roots and haustoria in 37 species of parasitic Scrophulariaceae was studied using light microscopy. The mature haustorium consists of two regions: the swollen “body” and the parent root, which resembles non-haustorial roots in structure. The body arises from the parent root and is composed of an epidermis, cortex, central region of xylem (the vascular core), a region of parenchyma (the central parenchymatous core), and the portion of the haustorium contained in the host tissue (the endophyte). The xylem of the vascular core is composed predominately of vessel elements. The central parenchymatous core is composed of parenchyma and col-lenchyma. Vessels extend from the vascular core through the central parenchymatous core to the endophyte. The endophyte is composed of parenchyma cells and vessel elements. No phloem is present in the body of the haustorium. Early stages in the development of the haustorium are exogenous. Initial periclinal divisions in the epidermis or outer cortex are followed by hypertrophy of cortical parenchyma. These events are followed by development of the vascular core from the pericycle, attachment of haustorium to the host by a specialized layer of cementing cells or root hairs, and penetration of the host by dissolution of host cells.     

Fine structure of the host-fungus interface in orchid mycorrhiza

Summary Electron microscopy of protocorms of Dactylorhiza purpurella infected with a symbiotic Rhizoctonia sp. showed that the intracellular hyphae examined did not penetrate the plasmalemma of the host cell. Walls of hyphae within cells bore many hemispherical protuberances over which the host plasmalemma was closely pressed. we estimate that these protuberances would increase the area of contact between hyphae and host plasmalemma by about 15%. They were not found on hyphae growing on agar. Except for these protuberances, and some vesicles or tubules which invaginated the fungus plasmalemma, no other structures were seen which could be suggested to be adaptations to transport across the living fungus-host interface.     

树兰原球茎内生细菌群落多样性及功能分析

【目的】通过分析树兰原球茎内生细菌群落组成、多样性特征和促生功能,探究树兰种子萌发相关的核心细菌类群及生物学功能。【方法】以树兰原球茎(树兰种子在树皮基质上共生萌发、在树叶基质上共生萌发、在MS1培养基上非共生萌发)和共生萌发基质(松树皮、腐熟树叶)共5个样本为研究材料,采用高通量测序技术分析不同萌发条件下原球茎内生细菌的16S rRNA基因多样性,比较分析细菌群落多样性和物种组成特征,通过传统的内生细菌分离方法获得共生萌发原球茎内生细菌菌株,并进行促生潜力评价。【结果】从5个研究样本中共获得2 735个可操作分类单元(operational taxonomic unit, OTU),属于41门453科876属,其中变形菌门(Proteobacteria)和放线菌门(Actinobacteria)为优势门。主坐标分析(principal coordinates analysis, PCoA)结果表明,树兰原球茎与萌发基质细菌群落结构存在差异,非共生萌发原球茎与在树皮基质上共生萌发原球茎内生细菌群落结构最为接近。功能预测表明,在树叶基质上共生萌发的原球茎内生细菌固氮功能显著高于其他萌发条件。通过分离培养,共获得内生细菌19株,分属12属16种,其中鞭毛膨胀芽孢杆菌(Tumebacillus flagellatus)、Bradyrhizobium cenepequi和人参腐殖土魏茨曼氏菌(Weizmannia ginsengihumi)为共生萌发原球茎共有种;韩国假单胞菌(Pseudomonaskoreensis)和 W. ginsengihumi兼具有溶磷、产吲哚乙酸(indole-3-acetic acid, IAA)和铁载体的潜在能力。【结论】在不同环境中萌发的树兰原球茎均有丰富的内生细菌群落定殖;从共生萌发原球茎中分离的内生细菌具有固氮、溶磷、产IAA和铁载体等促生功能。本研究为兰科植物种子萌发相关微生物资源挖掘及兰科植物与微生物互作研究提供科学依据。     

Fungal coil formation ofRhizoctonia repens in seedlings ofGaleola septentrionalis (orchidaceae)

Protocorms or protocorms with roots of an achlorophyllous orchidGaleola septentrionalis were inoculated with isolates ofRhizoctonia repens, R. solani, andRhizoctonia spp. The seedlings were infected with eight of twelve isolates ofR. repens. Fungal coils were formed in the cells, which was suggestive of a symbiotic association. The other isolates caused soft rot or no infection to the protocorms or the protocorms with a root. Contribution No. 97, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Tsukuba, Ibaraki 305, Japan.     

Mode of Infection of Ascochyta Blight of Chickpea Caused by Ascochyta rabiei

Process of infection and histological changes with Ascochyta blight of chickpea caused by A. rabiei (Pass.) Labr. were studied by light microscopy. Germ tubes from conidia of the fungus penetrate the stem tissue at the juncture of two epidermal cells and form subepidermal aggregates until the fourth day. On the sixth day, yellowing and necrotisation of host tissue coincides with formation of mature pycnidia. Fungus causes extensive damage to cellulosic cell walls of parenchymatous cortical and pith tissues in advance of invading hyphae indicating involvement of cell wall degrading enzymes. Lignified tissues, particularly xylem tracheary elements, remain intact.