昆明地区印度块菌子囊果的解剖结构研究

通过印度块菌子囊果石蜡切片的显微观察,对印度块菌子囊果包被及子实层的显微结构、子囊及子囊孢子的发育过程进行研究.结果表明:(1)印度块菌子囊果是由包被和子实层构成,子囊果的表面密被大量大小不一的疣状突起,包被由外皮层和内皮层构成;子实层由封闭的、大小不一的产孢组织构成,在产孢组织中包含有侧丝、产囊丝、子囊和子囊内的子囊孢子;(2)成熟印度块菌子囊果横切面上有明暗相间的迷宫状纹脉;(3)子囊卵形,由产囊丝顶端的细胞发育而来;(4)成熟子囊孢子红褐色,椭圆形至近球形不等,子囊孢子双层壁,外壁密布有刺状纹饰.子囊孢子在子囊内的发育过程中常出现败育现象,每个成熟子囊中含有1～5个子囊孢子(常见4个).     

内蒙古贺兰山某块菌的形态解剖学与分子生物学研究

利用形态解剖学和分子生物学方法,对采自内蒙古贺兰山地区实验样地青海云杉林下的块菌两菌株（菌株a和b）进行分析鉴定。研究发现：（1）两菌株子囊果均为黄褐色,表面光滑,没有明显的疣状突起和棱角。（2）菌株a产孢组织乳白色、致密团状,菌肉组织褐色;球形、棒状子囊呈蜂窝状排布,内含有1～4个带包被的、表面具有突起状纹饰的球型子囊孢子;子囊孢子双层壁,厚约1.7 μｍ,直径约20 μｍ（含纹饰）。（3）菌株b产孢组织有裂隙,松散,子实层内除了具有上述蜂窝状排布的子囊和内部的球型孢子外,还具有“口袋”状子囊,该子囊内含有大量两端尖、外壁光滑、褐色的椭球型孢子。（4）分子生物学进化分析表明,两菌株聚为一支,但属于块菌属的支持率相对较低;推断两菌株可能为中国猪块菌属Choiromyces新记录种。     

中国地下子囊菌新记录属——史蒂芬块菌属

文中首次报道了史蒂芬块菌属Stephensia在中国的分布.史蒂芬块菌发现于滇中地区呈贡县,生于l株栽培的天麻旁边,附近长有云南松和榛属植物.标本的特征与文献中对于该种的描述一致,即子囊果表面具褐色绒毛,产孢组织有曲折的脉沟,脉沟向中心辐聚,中心有时形成空腔,孢子球形,直径18～25 μm,无油滴,包被(外囊盘被)角胞组织.中国标本的ITS序列与北美和欧洲样品有99％的相似性,其LSU序列仅有3个碱基与北美样品不同.史蒂芬块菌在分子系统上与腔囊块菌属Hydnocystis和地杯菌属Geopxyis近缘.     

用传统分离培养法和高通量测序技术分析印度块菌子囊果内细菌的群落结构

块菌是重要的经济真菌, 在其生长发育过程中, 细菌扮演了重要角色。本文利用传统分离培养方法和高通量测序技术分析了印度块菌(Tuber indicum)子囊果内细菌的群落结构。共分离得到细菌532株, 根据物种累积曲线, 选取其中的112株细菌进行了16S rRNA基因序列分析, 共鉴定出4属40种, 其中假单胞菌属(Pseudomonas)菌株占所测菌株数的80%, 不动杆菌属(Acinetobacter)占12.5%, 链霉菌属(Streptomyces)占5%, 贪噬菌属(Variovorax)占2.5%。通过对印度块菌子囊果16S rRNA基因的V1-V3区高通量测序分析, 共获得细菌序列9,862条, 分属于7门43属220种, 其中变形菌门、拟杆菌门和放线菌门的物种占总物种数的99.7%, 是印度块菌子囊果内的优势细菌。黄杆菌属(Flavobacterium)、壤霉菌属(Agromyces)、微杆菌属(Microbacterium)、剑菌属(Ensifer)和寡养食单胞菌属(Stenotrophomonas)的物种数占总物种的86.3%, 是印度块菌子囊果内细菌的优势属。研究结果表明, 采用胰蛋白大豆培养基仅分离得到印度块菌子囊果内少数细菌物种, 而采用高通量测序技术分析发现, 印度块菌子囊果内细菌物种种类丰富, 群落结构复杂。     

中国果疣衣属地衣的研究

果疣衣属地衣系子囊菌门Ascomycota,子囊菌纲Ascomycetes,茶渍衣亚纲Lecanoromycetidae,鸡皮衣目Pertusariales,鸡皮衣科Pertusariaceae的成员。由于粉色果疣衣Varicellariarhodocarpa在中国的首次发现,使中国地衣区系中新增添了一个属:果疣衣属Varicellaria。该属迄今已知仅含三种,即粉芽果疣衣V.kemensis,八孢果疣衣V.carneonivea及粉色果疣衣V.rhodocarpa。果疣衣属为壳状地衣,地衣体微薄,膜质;子囊盘茶渍型,单个或数个聚生于瘤状果疣中;类侧丝多分枝并呈网状缠绕;子囊内含单孢或八孢;子囊孢子大型(长度为200~400mm),双胞,无色透明,椭圆形;孢子壁厚达27mm;与鸡皮衣属不同之处在于前者子囊内含双胞孢子,后者子囊内含单胞孢子。由于该属在中国是首次被发现,为了进一步的研究,文中还提供了该属迄今已知的全部三种的分种检索表。粉色果疣衣以其地衣体基本无粉芽和遇Pd呈负反应而区别于粉芽果疣衣,以子囊内含单孢而区别于八孢果疣衣。通过薄板层析法首次从该种髓部检测出茶渍衣酸。其地理成分为北极高山种,主要分布于欧洲的挪威、瑞典、芬兰、阿尔卑斯山脉,喀尔巴阡山脉、苏格兰以及北美洲;在亚洲迄今只见于日本与中国。     

中国果疣衣属地衣的研究

果疣衣属地衣系子囊菌门Ascomycota,子囊菌纲Ascomycetes,茶渍衣亚纲Lecanoromycetidae,鸡皮衣目Pertusariales,鸡皮衣科Pertusariaceae的成员。由于粉色果疣衣Varicellaria rhodocarpa在中国的首次发现,使中国地衣区系中新增添了一个属：果疣衣属Varicellaria。该属迄今已知仅含三种,即粉芽果疣衣V.kemensis,八孢果疣衣V.carneonivea及粉色果疣衣V.rhodocarpa。果疣衣属为壳状地衣,地衣体微薄,膜质;子囊盘茶渍型,单个或数个聚生于瘤状果疣中;类侧丝多分枝并呈网状缠绕;子囊内含单孢或八孢;子囊孢子大型(长度为200～400μm),双胞,无色透明,椭圆形;孢子壁厚达27μm;与鸡皮衣属不同之处在于前者子囊内含双胞孢子,后者子囊内含单胞孢子。由于该属在中国是首次被发现,为了进一步的研究,文中还提供了该属迄今已知的全部三种的分种检索表。粉色果疣衣以其地衣体基本无粉芽和遇Pd呈负反应而区别于粉芽果疣衣,以子囊内含单孢而区别于八孢果疣衣。通过薄板层析法首次从该种髓部检测出茶渍衣酸。其地理成分为北极高山种,主要分布于欧洲的挪威、瑞典、芬兰、阿尔卑斯山脉,喀尔巴阡山脉、苏格兰以及北美洲;在亚洲迄今只见于日本与中国。     

虫草成熟子囊壳、子囊与子囊孢子的电镜观察

虫草子囊壳壁为拟薄壁组织,基部与子座菌丝相联,顶端有一孔口,其内无缘丝,中心腔内无侧丝,基部着生的子囊垂直平行排列。子囊顶端中央是乳状突起,围以隆起的环状膜质边缘。成熟时,其顶端乳状突起膨大,膜质边缘也随之翻卷,中央有一小孔。同一子囊壳内子囊顶端发育阶段不同,说明子囊的形成不同步。子囊内含有两条平行的具横隔的子囊孢子。虫草子囊顶端形态结构即不象虫草属模式种蛹虫草,也不象头状虫草,说明子囊顶端的形态结构的种间差异。     

紫红曲有性阶段的研讨

紫红曲因在其菌丝体及孢子生长过程中,具有合成某些药用及色素物质功能而被重视。这些物质在东方国家中早被用于医疗及食物染色方面。本文在阐明该菌闭襄壳内数目众多的子囊孢子系来自多数子囊,其子囊壁在发育早期即已消失。具8个子囊孢子的单一子囊的确时有发生,所以红曲属名拉丁文原意“单一子囊”,虽然有时极易被置凝,但基本是正确的。此菌之另一显著特性为一次性结合可产生多数产囊丝钩及发育后的闭囊壳。此现象导致孢子形成以子囊孢子数目远超过分生孢子。     

中国地衣新记录属——裂衣属（英文）

报道了中国文字衣科地衣一新记录属——裂衣属(Chapsa A.Massal.)及其2新记录种,即印度裂衣(C.indica A.Massal.)和斑果裂衣[C.leprocarpa(Nyl.)A.Frisch],标本来自海南和广西。该属主要特征是:地衣体壳状、树皮生;具子囊盘类或色盘衣类的子囊果,固有果壳融合或不明显,具侧生侧丝;具横隔或砖壁型胞室的子囊孢子。     

中国地下子囊菌新记录属——史蒂芬块菌属（英文）

文中首次报道了史蒂芬块菌属Stephensia在中国的分布。史蒂芬块菌发现于滇中地区呈贡县,生于1株栽培的天麻旁边,附近长有云南松和榛属植物。标本的特征与文献中对于该种的描述一致,即子囊果表面具褐色绒毛,产孢组织有曲折的脉沟,脉沟向中心辐聚,中心有时形成空腔,孢子球形,直径18~25μm,无油滴,包被(外囊盘被)角胞组织。中国标本的ITS序列与北美和欧洲样品有99%的相似性,其LSU序列仅有3个碱基与北美样品不同。史蒂芬块菌在分子系统上与腔囊块菌属Hydnocystis和地杯菌属Geopxyis近缘。     

Tuber melanosporum outcrosses: analysis of the genetic diversity within and among its natural populations under this new scenario

Tuber melanosporum is an ectomycorrhizal ascomycete producing edible ascocarps. The prevalent view is that this species strictly selfs, since genetic analyses have never detected heterozygotic profiles in its putatively diploid/dikaryotic gleba. The selfing model has also forged the experimental approaches to assess the population genetic variability. Here, the hypothesis that T. melanosporum outcrosses was tested. To this end, SSR (simple sequence repeats) and ITS (internal transcribed spacer) markers were employed to fingerprint asci and the surrounding gleba within single ascocarps. The distribution of genetic variability was also investigated at different geographical levels using single (SSR and ITS) and multilocus (AFLP, amplified fragment length polymorphism) markers. It is shown that T. melanosporum outcrosses since asci display additional alleles besides those present in the surrounding, uniparental, gleba. Furthermore, SSR and AFLP data reveal a high rate of intrapopulation diversity within samples from the same ground and root apparatus and the highest rate of genetic variability within the southernmost populations of the distributional range. These data call for a profound re-examination of T. melanosporum mating system, life cycle and strategies for managing man-made plantations. They also strongly support the idea that the last glaciation restricted the species distribution to the Italian and Spanish peninsulas.     

Incubation of excised apothecia enhances ascus maturation of Sclerotinia sclerotiorum

Synchronized maturation of ascospores of Sclerotinia sclerotiorum is desirable for establishing a transformation system, conducting genetic analyses of the pathogen, defining the precise epidemiological roles of ascospores and screening plant germplasm for resistance. In general, fresh apothecia collected from germinated sclerotia contained primarily immature or discharged asci. This study was undertaken to investigate whether maturation of asci and ascospores could be enhanced by incubation of excised apothecia and to determine the effects of factors such as temperature, excision time, light and ventilation on maturation of asci and ascospores in excised apothecia. Maturation of asci was compared between intact and excised apothecia that were incubated under similar conditions. Results demonstrated that temperature was an important factor affecting ascus maturation of S. sclerotiorum during incubation of excised apothecia, and the optimum temperature was around 21 C. After incubation at 21 C for 30 h, the percentage of undischarged mature asci in excised apothecia increased up to 70-80%. This increase was accompanied by a significant increase in ascospore production of up to 5 x 10(5) ascospores per apothecium. Detailed time course studies indicated that mature asci peaked at 30-36 h of postexcision incubation. Mature asci and the number of ascospores were higher in open incubation than in closed incubation, suggesting that accumulation of volatile substances was not required for ascus/ascospore maturation during postexcision incubation and ventilation could enhance the maturation process. Light also did not affect the maturation of asci during the incubation of excised apothecia. Germination rates for ascospores from excised apothecia under various treatments were similar to those from untreated apothecia but declined slightly with time postexcision. The incubation of excised apothecia promoted ascus maturation compared with intact apothecia.     

Morphology,development and cytology of Taphrina maculans Butler

Morphology, development and nuclear behavior of the ascogenous stroma and asci in the infection spots have been described inTaphrina maculans Butler. The fungus forms subcuticular and intercellular mycelium in the leaf tissues and the ascogenous layers originate through division of the subcuticular hyphal cells in the infection sites. Germination of ascogenous cells starts with their elongation in the uppermost layer forming asci and ascospores without formation of stalk cells. Meiosis of the fusion (diploid) nucleus occurs in the young ascus as in otherTaphrina species devoid of stalk cells. The haploid chromosome complement in this species consists of 3 chromosomes (n=3). All the cells in the stromatic layer are potential ascogenous cells and ascus formation continues, until all of them are exhausted in the infection spot. Eight ascospores are normally formed in each ascus, but multi-plication of ascospores may occurin situ later. Three morphologically distinct types of ascus opening are encountered, which are apparently not correlated with prevalent environment. Multiplication of ascospores after their discharge from mature asci occurs by budding proceded by a mitotic division of the spore nucleus. Blastospores (budded cells) germinate into short hyphae and binucleate condition of cells originates by mitotic division of the nucleus. Occurrence of giant cells containing 2 nuclei is often observed. Possible origin of Uredinales fromTaphrina-like ancestors has been indicated due to their close resemblance.     

Substructural studies on sporulation of Saccharomycopsis lipolytica

During sporulation of diploids from crosses between different strains of the yeast Saccharomycopsis (Candida) lipolytica irregular numbers of ascospores per ascus have been observed. Using the serial section method it could be shown now by means of electron microscopy that in one-, two-, and three-spored asci unenclosed "naked" nuclei occur additionally to nuclei incorporated in mature spores. It was demonstrated that the production of less than four spores per ascus in this yeast is not the result of a lack of meiotic products but of the nonutilization of nuclei from meiosis. In 2--4 spored asci usually four products of meiosis in form of enclosed and free nuclei could be demonstrated which indicate a normal meiotic division. All ascospores derived from asci with different spore numbers are uninuclear. It is assumed that a defect in spore formation caused by structural changes of chromosomes or aneuploidy should give rise to the occurrence of non incorporated nuclei and spore irregularity. It was concluded that meiosis and spore formation in Saccharomycopsis lipolytica seem to represent parallel and coordinated processes which generally resemble those recorded for Saccharomyces cerevisiae and Hansenula species.     

Programmed ascospore death in the homothallic ascomycete Coniochaeta tetraspora

Immature asci of Coniochaeta tetraspora originally contain eight uninucleate ascospores. Two ascospore pairs in each ascus survive and mature, and two die and degenerate. Arrangement of the two ascospore types in individual linear asci is what would be expected if death is controlled by a chromosomal gene segregating at the second meiotic division in about 50% of asci. Cultures originating from single homokaryotic ascospores or from single uninucleate conidia are self-fertile, again producing eight-spored asci in which four spores disintegrate, generation after generation. These observations indicate that differentiation of two nuclear types occurs de novo in each sexual generation, that it involves alteration of a specific chromosome locus, and that the change occurs early in the sexual phase. One, and only one, of the two haploid nuclei entering each functional zygote must carry the altered element, which is segregated into two of the four meiotic products and is eliminated when ascospores that contain it disintegrate. Fusion of nuclei cannot be random-a recognition mechanism must exist. More study will be needed to determine whether the change that is responsible for ascospore death is genetic or epigenetic, whether it occurs just before the formation of each ascus or originates only once in the ascogonium prior to proliferation of ascogenous hyphae, and whether it reflects developmentally triggered alteration at a locus other than mating type or the activation of a silent mating-type gene that has pleiotropic effects. Similar considerations apply to species such as Sclerotinia trifoliorum and Chromocrea spinulosa, in which all ascospores survive but half the spores in each ascus are small and self-sterile. Unlike C. tetraspora, another four-spored species, Coniochaetidium savoryi, is pseudohomothallic, with ascus development resembling that of Podospora anserina.     

Studies on the development of perithecium of Ceratocystis stenoceras

The development of the perithecium of Ceratocystis stenoceras was observed by a light microscope and by a scanning electron microscope.The fungus has developed dark brown perithecia on wheat agar medium in three days of incubation. Perithecial primordia appeared as tightly knotted coils. At the center of it an oval ascogonium was observed. The ascogonium was developed from a lateral wall of a hypha, and the hyphae covering the ascogonium branched at the basal part where the ascogonium was attached. These hyphae branched repeatedly in the developmental growth to cover the ascogonium, and it was finally covered tightly. The plasmogamy of this fungus is much probably performed by the gametangial contact. As the stage proceeded, the ascogonium elongated, the terminal and the basal portions of it swelled and cleavage of the ascogonium resulted. Each of the cleaved ascogonia germinated continuously and stretched out the ascogenous hyphae. About that time the cells consisting of perithecia were vacuolated from the center and successively dissolved, so that a space was formed in the center of the body. Ascogenous hyphae continued to develop downwards, and their end were fixed to the inner wall of the body.The upper portion of the hyphae converged to the center of the body and the ascogenous hyphae became the supporting tissue for ascus formation.Hook formation was observed prior to the ascus formation. After completion of karyogamy by hook formation, the fissure appeared on the ascus and the end portion was released. The released portion included eight ascospores. The ascus had a smooth surface and no special structure was seen on the top. As the asci were matured, they evanesced by themselves and concurrently ascospores came out. Finally the body was massively filled with ascospores.     

Oxylipin-coated hat-shaped ascospores of Ascoidea corymbosa

We previously implicated 3-hydroxy oxylipins and ascospore structure in ascospore release from enclosed asci. Using confocal laser scanning microscopy on cells stained with fluorescein-coupled, 3-hydroxy oxylipin-specific antibodies, we found that oxylipins are specifically associated with ascospores and not the vegetative cells or ascus wall of Ascoidea corymbosa. Using gas chromatography--mass spectrometry the oxylipin 3-hydroxy 17:0 could be identified. Here, we visualize for the first time the forced release of oxylipin-coated, hat-shaped ascospores from terminally torn asci, probably through turgor pressure. We suggest that oxylipin-coated, razor-sharp, hat-shaped ascospore brims may play a role in rupturing the ascus to affect release.     

Possible involvement of Pseudomonas fluorescens and Bacillaceae in structural modifications of Tuber borchii fruit bodies

Previous studies on Tuber borchii fruit bodies in early maturation stages suggested a role of bacteria in sporocarp structural modifications. In order to verify this hypothesis, in the present study we investigated by means of microbial and ultrastructural approaches, the bacterial population of T. borchii sporocarps from intermediate maturation phases to advanced decomposition stages, paying particular attention to chitinolytic and cellulolytic bacteria and to their relationships with ascii and ascospores. We found that Pseudomonas fluorescens and spore-forming Bacillaceae, both able to degrade cellulose and chitin, are present inside the sporocarps in all maturation stages investigated. Moreover, rod-shaped bacteria seem able to erode ascus walls and colonize the interior of ascii containing mature spores. These results suggest a possible role of these bacteria in the process of ascus opening. Moreover, the presence of P. fluorescens and Bacillaceae on isolated mature spores after decontamination suggests an intimate association between these bacteria and the ascospores.