青花菜花粉母细胞减数分裂及雄配子体发育

采用染色体制片及爱氏苏木精染色-冬青油透明技术对青花菜花粉母细胞减数分裂及雄配子体发育过程进行了细胞学研究.结果表明:花粉母细胞减数分裂的细胞质分裂为同时型,四分体为正四面体型或十字交叉型;中期Ⅰ和中期Ⅱ,少数细胞可见赤道板外染色体;后期Ⅰ和后期Ⅱ部分细胞出现染色体桥及落后染色体;四分体时期可观察到二分体、三分体及含微核的异常四分体.雄配子体发育过程包括2次有丝分裂,成熟花粉为3细胞型,具3个萌发孔.减数分裂过程中染色体行为异常的花粉母细胞约占10.28%;雄配子体发育过程中异常频率约为3.2%,败育主要发生在单核期.     

OT杂种系百合品种‘Cocossa’小孢子败育细胞学研究

以OT百合‘Cocossa’为材料,采用醋酸洋红染色烤片法和石蜡切片法,对该品种花粉母细胞减数分裂过程以及绒毡层在花粉母细胞发育过程中的变化进行系统的细胞学观察。研究发现:(1)当百合花蕾长度在2.5~4.5 cm时,花粉母细胞处在减数分裂时期。(2)在花粉母细胞减数分裂的过程中,出现了较多染色体异常现象:中期Ⅰ出现染色体环;后期Ⅰ出现了滞后染色体和染色体桥;在末期Ⅰ和末期Ⅱ细胞出现不均等分裂和微核;处于同一花蕾和同一花药的花粉母细胞减数分裂具有不同步性,能同时观察到2个不同时期的分裂相;形成畸形、无核、多核的异常小孢子。(3)在末期Ⅱ和单核花粉粒时期,绒毡层延迟降解,引起多核花粉粒、畸形花粉粒以及花粉粒自溶现象。结果表明:OT百合‘Cocossa’小孢子败育是花粉母细胞异常减数分裂与绒毡层异常降解共同导致的。     

二倍体芒小孢子发生及雄配子体发育研究

该实验通过采集天然二倍体芒不同发育时期的幼穗,进行卡宝品红染色压片和石蜡切片制作,观察芒的花药发育过程,为芒的生殖生物学及其系统发育研究奠定理论基础。结果表明:(1)天然二倍体芒雄蕊3枚,雄蕊花药四室,花药壁由4层细胞组成,从外向内依次是表皮、药室内壁、中层、绒毡层,花药壁发育属于基本型;花药成熟时,中层和绒毡层降解消失,或者仅存痕迹,只剩表皮和纤维层细胞,但此时可观察到部分绒毡层降解延迟现象。(2)花粉母细胞减数分裂为连续型,成熟花粉粒为3-细胞型;花粉母细胞减数分裂后期Ⅱ出现染色体分裂不同步现象。(3)雄配子体发育过程中,同一花粉囊的花粉粒发育不同步;雌、雄配子体发育也不同步,且雄蕊先成熟。     

短葶飞蓬减数分裂、雄配子体发育过程及其花部形态特征

运用压片-透明法对短葶飞蓬(Erigeron breviscapus)小孢子母细胞减数分裂、雄配子体的发育过程进行了观察,并探讨了它们与花部形态特征的关系。结果表明,短葶飞蓬小孢子母细胞减数分裂的胞质分裂为同时型,四分体主要为四面体型,成熟花粉为3-细胞型;花序和花蕾形态变化与减数分裂、雄配子体的发育时期具有一定相关性,其中花蕾的长度可有效确定该花蕾中减数分裂与雄配子体发育时期。     

短葶飞蓬减数分裂、雄配子体发育过程及其对应的花部形态特征

运用压片-透明法对短葶飞蓬(Erigeron breviscapus)小孢子母细胞减数分裂、雄配子体的发育过程进行了观察,并探讨了它们与花部形态特征的关系。结果表明,短葶飞蓬小孢子母细胞减数分裂的胞质分裂为同时型,四分体主要为四面体型,成熟花粉为3-细胞型;花序和花蕾形态变化与减数分裂、雄配子体的发育时期具有一定相关性,其中花蕾的长度可有效确定该花蕾中减数分裂与雄配子体发育时期。     

桔梗花粉母细胞减数分裂及雄性败育的细胞生理学研究

以桔梗不育系PA及其保持系PB为试验材料,采用石蜡切片和改良苯酚品红染色压片法对花粉母细胞减数分裂和雄配子体发育过程进行比较,探讨桔梗雄性不育系小孢子形成过程和败育发生的细胞生理学机理。结果表明:(1)桔梗保持系PB花粉母细胞减数分裂的细胞质分裂为同时型,同一花药减数分裂较同步;在中期Ⅰ和中期Ⅱ,少数细胞中可见赤道板外染色体;四分体以四面体为主,成熟花粉粒为二核花粉。(2)不育系PA花粉母细胞减数分裂后期Ⅰ开始出现异常,表现为细胞质形态改变,末期Ⅱ之后细胞质不能分裂,形成异常四分体,胼胝质壁不能溶解,四分体难以释放出游离小孢子而被降解,导致败育。(3)在发育过程中,桔梗不育系花蕾游离脯氨酸、可溶性蛋白含量低于保持系,而SOD活性、丙二醛含量均高于保持系。(4)桔梗不育系PA及其保持系PB花粉母细胞减数分裂和雄配子体发育过程存在明显差异,桔梗雄性败育过程大体可分为4个阶段,即后期Ⅰ细胞质异常、末期Ⅱ之后细胞质不能分裂、四分体难以释放游离小孢子、四分体被降解仅残留碎片。研究认为,桔梗不育花蕾(开花前)生长发育过程中,体内活性氧代谢紊乱、丙二醛积累及游离脯氨酸等"物质代谢损亏"可能是引起桔梗雄性败育的原因。     

三倍体芍药品种花粉母细胞减数分裂行为观察与比较

芍药是中国传统名花,我国品种均为二倍体,培育多倍体新品种是一项长期的育种目标。本研究选取3个芍药三倍体新品种,采用植物染色常规压片法观察其花粉母细胞的减数分裂情况。结果显示:(1)同一品种不同花蕾直径大小的花粉母细胞所处的分裂状态不同,同一品种同一花蕾直径大小花粉母细胞有不同步分裂现象,但大多数表现为相同的分裂相;(2)不同品种的相近花蕾直径大小所处的分裂时期也不同,有比较显著的差异,因此直径不能作为判断减数分裂时期的唯一的标准;(3)三倍体品种花粉母细胞减数分裂存在单价体、三价体、染色体桥、染色体不均等分离等染色体异常行为,这些异常行为使一些遗传物质缺失或最终形成二分体或三分体,导致三倍体花粉的育性非常低。该研究为掌握芍药三倍体减数分裂规律及多倍体育种奠定了细胞学基础。     

温度对斯托克通氏烟草雄配子体形成和发育的影响

为探究低温对斯托克通氏烟草(Nicotiana stocktonii)花粉母细胞(PMC)减数分裂及其雄配子体发育过程的影响,采用卡宝品红染色法,研究不同温度条件下该材料雄配子体形成和发育的过程。结果表明:种植于昼温(31±0.5)℃、夜温(11±0.5)℃人工气候箱中的Nicotiana stocktonii花粉母细胞减数分裂过程异常现象较少,出现微核的比率较低,用新鲜成熟的花粉做萌发实验花粉萌发率较高,为(71±3)%; 而种植于昼温(25±0.5)℃、夜温(3±0.5)℃条件下的Nicotiana stocktonii开花后花药大多干瘪,用新鲜成熟花粉做萌发实验花粉萌发率低,为(13.67±3)%,花粉母细胞减数分裂过程出现染色体桥、染色体不同步、染色体断片、落后染色体等现象,存在微核的细胞比率较高。因此,Nicotiana stocktonii花粉母细胞减数分裂与小孢子发育过程易受温度影响,从而影响花粉的可育性。     

野蔷薇一变种红刺玫的细胞学研究

以野蔷薇的-变种红刺攻(Rosa multiflora Thunb.vat.cathayensis Rehd.)为材料,对其染色体数和花粉母细胞的减数分裂进程进行了研究.结果表明:红刺玫染色体数目为2n=3x=21,为三倍体;减数分裂始于4月上旬,此时花苞开始膨大、但未开裂,花瓣由绿变成黄色;在同一花药中,花粉母细胞的减数分裂并不同步,可以观察到前期到末期Ⅱ之间各个时期的分裂相;在其减数分裂过程中存在诸如单价体、染色体桥、落后染色体等一系列异常现象.实验还从细胞遗传学上分析了红刺玫育性与花粉母细胞减数分裂异常的关系,部分可育花粉的存在为红刺玫育种实践提供了有用的材料.     

百合花粉母细胞减数分裂及其雄配子体发育观测

以百合“Siberia”品种为材料,采用染色压片法对花粉母细胞减数分裂和雄配子体形成进行了系统的细胞学观察,结果表明：百合花药6枚,花药4室,胞质分裂方式为连续型,四分体小孢子排列方式为四面体型和十字型,成熟花粉为二细胞型,具1个萌发沟。百合同一植株、同一花蕾乃至同一花药,能观察到2～4个分裂相,减数分裂具不同步性,这是适应环境的一种进化表现,对其种群繁殖具有重要意义。     

Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller)

Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.     

Molecular phylogeny of Phebalium (Rutaceae: Boronieae) and related genera based on the nrDNA regions ITS 1+2

Parsimony analyses of the internal transcribed spacer regions of nuclear ribosomal DNA (ITS 1 & ITS 2) for 38 taxa sampled from the Phebalium group (Rutaceae: Boronieae) and two outgroups confirm that, with the exception of Phebalium sensu stricto and Rhadinothamnus, six of the currently recognised genera within the group are monophyletic. The data indicate that Phebaliums. str. is paraphyletic with respect to Microcybe, and Rhadinothamnus is paraphyletic with respect to Chorilaena. Rhadinothamnus and Chorilaena together are the sister group to Nematolepis. Drummondita, included as an outgroup taxon, clustered within the ingroup as sister to Muiriantha and related to Asterolasia.The phylogeny suggests that the evolution of major clades within a number of these genera (e.g. Phebalium) relates to vicariance events between eastern and south-western Australia. Leionema is an eastern genus, with the most basal taxon being the morphologically distinct Leionema ellipticum from northern Queensland. Leionema also includes one species from New Zealand, but this species (as with some others) proved difficult to sequence and its phylogenetic position remains unknown. Taxonomic changes at the generic level are recommended.The authors wish to thank Paul G.Wilson, PERTH, for advice and discussion, and Paul Forster, BRI, for collecting and providing material of Leionema ellipticum. The project was supported by a Melbourne University Postgraduate Award (to BM), the Australian Biological Resources Study (ABRS), Australian Systematic Botany Society and Wolf Den (Australia) Investments.     

New species and new combinations in Peruvian Orchidaceae

seventeen new species and combinations are proposed in the generaChondrorhyncha, Cischweinfia, Cochlioda, Eloyella, Encyclia, Kefersteinia, Koellensteinia, Macroclinium, Rodriguezia, Solenidiopsis, andStenia. All new species are illustrated. A key is provided for 2-flowered species ofMacroclinium, PeruvianSigmatostalix, and PeruvianStenia. Solenidium (Solenidiopsis) peruvianum Schltr. is lectotypified.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

安徽牯牛降的丝孢菌Ⅰ

本文报导作者采自安徽枯牛降自然保护区的18种丝孢菌,分属于5个属,其中有3个新种:牛皮冻生尾孢(Cercospora paederiicola),山鸡椒假尾饱(Pseudocercospora litseae-cubebae),鸡血藤生假尾孢(P. millettiicola)和2个中国新纪录。文中对新种进行了描述及绘图,新记录种作了简要说明。研究的标本保存在中国科学院微生物研究所真菌标本室(HMAS)。     

Changes of dung beetle communities from rainforests towards agroforestry systems and annual cultures in Sulawesi (Indonesia)

Little is known about how tropical land-use systems contribute to the conservation of functionally important insect groups, including dung beetles. In a study at the margin of Lore Lindu National Park (a biodiversity hotspot in Central Sulawesi, Indonesia) dung-beetle communities were sampled in natural forest, young secondary forest, agroforestry systems (cacao plantations with shade trees) and annual cultures (maize fields), each with four replicates (n = 16 sites). At each site we used 10 pitfall traps, baited with cattle dung, along a 100 m transect for six 3-day periods. The number of trapped specimens and species richness at the natural forest sites was higher than in all land-use systems, which did not significantly differ. Each land-use system contained, on average, 75% of the species richness of the natural forest, thereby indicating their importance for conservation. However, a two-dimensional scaling plot based on NESS indices (m = 6) indicated distinct dung beetle communities for both forest types, while agroforestry systems and annual cultures exhibited a pronounced overlap. Mean body size of dung beetles was not significantly influenced by land-use intensity. Five of the six most abundant dung beetle species were recorded in all habitats, whereas the abundance of five other species was significantly related to habitat type. Mean local abundance and number of occupied sites were closely correlated, further indicating little habitat specialisation. The low dung beetle diversity (total of 18 recorded species) may be due to the absence of larger mammals in Sulawesi during historical times, even though Sulawesi is the largest island of Wallacea. In conclusion, the dung beetle fauna of the lower montane forest zone in Central Sulawesi appears to be relatively robust to man-made habitat changes and the majority of species did not exhibit strong habitat preferences.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Phylogenetic investigations of Sordariaceae based on multiple gene sequences and morphology

The family Sordariaceae incorporates a number of fungi that are excellent model organisms for various biological, biochemical, ecological, genetic and evolutionary studies. To determine the evolutionary relationships within this group and their respective phylogenetic placements, multiple-gene sequences (partial nuclear 28S ribosomal DNA, nuclear ITS ribosomal DNA and partial nuclear β-tubulin) were analysed using maximum parsimony and Bayesian analyses. Analyses of different gene datasets were performed individually and then combined to generate phylogenies. We report that Sordariaceae, with the exclusion Apodus and Diplogelasinospora, is a monophyletic group. Apodus and Diplogelasinospora are related to Lasiosphaeriaceae. Multiple gene analyses suggest that the spore sheath is not a phylogenetically significant character to segregate Asordaria from Sordaria. Smooth-spored Sordaria species (including so-called Asordaria species) constitute a natural group. Asordaria is therefore congeneric with Sordaria. Anixiella species nested among Gelasinospora species, providing further evidence that non-ostiolate ascomata have evolved from ostiolate ascomata on several independent occasions. This study agrees with previous studies that show heterothallic Neurospora species to be monophyletic, but that homothallic ones may have a multiple origins. Although Gelasinospora and Neurospora are closely related and not resolved as monophyletic groups, there is insufficient evidence to place currently accepted Gelasinospora and Neurospora species into the same genus.     

Die GattungKarschia — Bindeglied zwischen bitunicaten Ascomyceten und lecanoralen Flechtenpilzen?

The genusKarschia, in the earlier sense, including saprophytes and parasites on lichens, has been thought to be a non-lichenized parallel genus of the lichen genusBuellia. Modern workers included it on the one hand inBuellia, on the other hand combined it with bitunicate ascomycetes. It is now proved thatKarschia is heterogeneous and contains but superficially similar members both of the genusBuellia of theLecanorales and of typical or masked bitunicateAscomycetes. Therefore, it can not be regarded as a link betweenLecanorales andDothideales. The type species ofKarschia belongs to theDothideales.