Helleborus foetidus - Helleborus purpurascens - Trillium nivale

AR

异叶苣苔属系统学和进化研究——兼论尖舌苣苔族的系统发育

异叶苣苔属(Whytockia)隶属于苦苣苔科(Gesneriaceae)、尖舌苣苔族(Klugieae)．70年代以来，该属作为Klugieae中最原始的类群才逐渐被人们所认识，并被认为是解决Klugieae系统发育问题的关键类群，但到目前为止，对该属变异式样及系统发育的认识仍然极其有限．鉴于上述原因，本文结合蜡叶标本和大量的野外观察和采集，从形态学、维管束的结构和分化，形态发生和细胞学等方面，进行异叶苣苔属的系统学和进化研究，并兼论尖舌苣苔族的系统发育． 1．通过对异叶苣苔属大量性状的仔细观察和比较，本文选择了34个性状，并分析了他们的变异式样及其形成原因，为进一步的系统学研究提供依据． 2．地上茎的形态发生研究揭示出异叶苣苔属植物的顶芽完全受到抑制，位于小型叶腋的侧芽萌发，从而替代顶芽生长，地上茎的不分枝是位于大型叶腋的腋芽受到抑制所致，该研究纠正了前人的观察错误． 3．花序及花的形态发生过程表明，异叶苣苔属的花序呈对花从花序轴内侧二列式连续发生，没有任何分枝和附属物．花各部分的发生顺序基本上呈向心式，但在花冠和雄蕊原基之间则为离心式发生．花萼和花冠原基的发生及发育顺序均呈下降式，从而使花萼和花冠在芽中呈下降覆瓦状排列，退化雄蕊是由发育停滞所致．雌蕊的两个心皮在形态发生过程中由离生到合生，该属具中轴胎座的二室子房起源于两个离生心皮的近轴面内卷式愈合，柱头从离生到合生决定于个体发育中愈合部向上推进的程度． 4．为了澄清性状演化极性这一关键问题、本文作了花部器官解剖以及心皮维管束结构及分化过程的研究，结果表明，该属花梗和花萼中均具有分泌道和雄蕊束从中柱独立分出，同独叶苣苔属(Monophyllaea)十分相似：花盘低且薄并且没有维管束，以及子房壁维管束具有不同来源而区别于尖舌苣苔族(Klugieae)中的其它类群．异叶苣苔属的心皮结合程度和胎座形态可分为三种类型，即A型：心皮结合部的中轴区膨大，但四个瓣片的上部分离、B型：除中轴区膨大外，四个瓣片也成对愈合，胎座呈锚形、C型：中轴区不膨大，四个瓣片完全分离，子房上部一室．前者保留了较多的叶性，可能是该属乃至尖舌苣苔族中最原始心皮及胎座形态．后二者代表着两个相反的演化趋势． 5．本文首次报道了异叶苣苔属的染色体数目和核型，染色体数目均为2n＝18，x＝9．核型分别是2A或3A．核型的演化趋势，即从对称到不对称和随体的丢失同外部形态的变异密切相关。 6．深入地比较和分析了异叶苣苔属和其他类群的关系以及性状的演化趋势，并运用分支分析方法，重建属的系统发育． 7．生态、地理分布和演化的研究表明：异叶苣苔属的多样化中心分别是云南东南部和滇、贵、川交界区域，起源于第三纪或更早期的古热带湿润性森林植物区系，起源地可能是两个现代多样化中心所连接的整个区域，即：滇东南至滇贵川交界区域． 8．本文对异叶苣苔属进行全面的分类学修订，包括7个种，其中一个新种，新组合1个种和一个变种、根据该属的系统发育式样，在属下新设两个组．系统排列如下： 异叶苣苔属Whytockia W. W. Smith 组1：异叶苣苔组Sect. Whytockia Y. Z. Wang sect. nov. 1．河口异叶苣苔W. hekouensis Y. Z. Wang 2．毕节异叶苣苔W. bijieensis Y. Z. Wang, sp. nov. 3．异叶苣苔W. chiritiflora (Oliv.) W.W. Smith 4．峨眉异叶苣苔W. wilsonii (A. Weber) Y. Z. Wang, stat. nov. 5．紫红异叶苣苔W. purpurascens Y. Z. Wang 组2：台湾异叶苣苔组Sect. Synstigma Y. Z. Wang, sect. nov. 6．白花异叶苣苔W. tsiangiana (Hand.-Mazz) A. Weber 7．台湾异叶苣苔W. sasakii (Hayata)B．L．Burtt. 9．在异叶苣苔属系统学和进化研究的基础上，结合前人工作，本文进一步探讨尖舌苣苔族的系统发育．大量的证据充分显示出异叶苣苔属和圆果苣苔属分别是Klugieae最原始的类群，该族中的尖舌苣苔属(Rhynchoglossum)，盾座苣苔属(Epithema)和独叶苣苔属(Mono phyllaea)，可能是从Whytockia植物的早期类群直接演化而来，十字苣苔属(Stauranthera)和Loxonia也可能直接或间接来自Gyrogyne植物的早期类群．尖舌苣苔族植物可能起源于亚洲大陆或更准确地说，中国西南部地区，在随后的演化过程中，经过分化、迁移，逐渐形成广布于南亚、东南亚及太平洋岛屿至西非、中美洲的现代地理分布式样。

C. colchicum - variation measured by DNA sequence

Cyclamen colchicum has a mixed history in the hands of botanists. This paper examines the genetic identity of a group of wild Cyclamen populations from the Caucasus to discover whther they are Cyclamen colchicum, C. purpurascens or a mixture of the two. The collections supplemented by material collected at the type locality for C. colchicum, proved to be a single but variable genetic group of C. colchicum that was distinct from C. purpurascens.

Epicoccum nigrum P16, a Sugarcane Endophyte, Produces Antifungal Compounds and Induces Root Growth

Background: Sugarcane is one of the most important crops in Brazil, mainly because of its use in biofuel production. Recent studies have sought to determine the role of sugarcane endophytic microbial diversity in microorganism-plant interactions, and their biotechnological potential. Epicoccum nigrum is an important sugarcane endophytic fungus that has been associated with the biological control of phytopathogens, and the production of secondary metabolites. In spite of several studies carried out to define the better conditions to use E. nigrum in different crops, little is known about the establishment of an endophytic interaction, and its potential effects on plant physiology. Methodology/Principal Findings: We report an approach based on inoculation followed by re-isolation, molecular monitoring, microscopic analysis, plant growth responses to fungal colonization, and antimicrobial activity tests to study the basic aspects of the E. nigrum endophytic interaction with sugarcane, and the effects of colonization on plant physiology. The results indicate that E. nigrum was capable of increasing the root system biomass and producing compounds that inhibit the in vitro growth of sugarcane pathogens Fusarium verticillioides, Colletotrichum falcatum, Ceratocystis paradoxa, and Xanthomomas albilineans. In addition, E. nigrum preferentially colonizes the sugarcane surface and, occasionally, the endophytic environment. Conclusions/Significance: Our work demonstrates that E. nigrum has great potential for sugarcane crop application because it is capable of increasing the root system biomass and controlling pathogens. The study of the basic aspects of the interaction of E. nigrum with sugarcane demonstrated the facultative endophytism of E. nigrum and its preference for the phylloplane environment, which should be considered in future studies of biocontrol using this species. In addition, this work contributes to the knowledge of the interaction of this ubiquitous endophyte with the host plant, and also to a better use of microbial endophytes in agriculture.

Epicolactone - Natural Product Isolated from the Sugarcane Endophytic Fungus Epicoccum nigrum

The endophytic fungus Epicoccum nigrum was isolated from sugarcane and the bioguided fractionation of the ethyl acetate extract led to the isolation of epicolactone, mellein, and 4,5-dimethylresorcinol. Characterization of epicolactone by MS, NMR and X-ray crystallography revealed a new natural product with an unusual carbon skeleton. The production of this secondary metabolite decreased in mutants of Epicoccum nigrum transformed by Agrobacterium tumefaciens. Additionally, these mutants produced 4-hydroxymellein.

Studies on biotic and abiotic elicitors inducing defense responses in tomato

Tomato (Lycopersicon esculentum Mill., Solanum lycopersicon L.) is one of the most popular vegetable throughout the world, and the importance of its cultivation is threatened by a wide array of pathogens. In the last twenty years this plant has been successfully used as a model plant to investigate the induction of defense pathways after exposure to fungal, bacterial and abiotic molecules, showing triggering of different mechanisms of resistance. Understanding these mechanisms in order to improve crop protection is a main goal for Plant Pathology. The aim of this study was to search for general or race-specific molecules able to determine in Solanum lycopersicon immune responses attributable to the main systems of plant defense: non-host, host-specific and induced resistance. Exopolysaccharides extracted by three fungal species (Aureobasidium pullulans, Cryphonectria parasitica and Epicoccum purpurascens), were able to induce transcription of pathogenesis-related (PR) proteins and accumulation of enzymes related to defense in tomato plants cv Money Maker,using the chemical inducer Bion® as a positive control. During the thesis, several Pseudomonas spp. strains were also isolated and tested for their antimicrobial activity and ability to produce antibiotics. Using as a positive control jasmonic acid, one of the selected strain was shown to induce a form of systemic resistance in tomato. Transcription of PRs and reduction of disease severity against the leaf pathogen Pseduomonas syringae pv. tomato was determined in tomato plants cv Money Maker and cv Perfect Peel, ensuring no direct contact between the selected rhizobacteria and the aerial part of the plant. To conclude this work, race-specific resistance of tomato against the leaf mold Cladosporium fulvum is also deepened, describing the project followed at the Phytopathology Laboratory of Wageningen (NL) in 2007, dealing with localization of a specific R-Avr interaction in transfected tomato protoplast cultures through fluorescence microscopy.

Patterned-ground plant communities along a bioclimate gradient in the High Arctic, Canada

Non-sorted circles, non-sorted polygons, and earth hummocks are common ground-surface features ill arctic regions. The), are caused by a variety of physical processes that Occur in permafrost regions including contraction cracking and frost heave. Here we describe the vegetation of patterned-ground forms on zonal sites at three location!: along an N-S transect through the High Arctic of Canada. We made 75 releves on patterned-ground features (circles, polygons, earth hummocks) and adjacent tundra (Interpolygon, intercircle, interhummock areas) and identified and classified the vegetation according to the Braun-Blanquet Method. Environmental factors were correlated with the vegetation data using a nonmetric multidimensional scaling ordination (NMDS). We identified eleven commnunities: (1) Puccinellia angustata-Papaver radicalum community in xeromesic non-sorted polygons of subzone A of the Circumpolar Arctic Vegetation Map; (2) Saxifraga-Parmelia omphalodes ssp. glacialis community in hydromesic interpolygon areas of subzone A; (3) Hypogymnia subobscura-Lecanora epibryon community In xeromesic non-sorted polygons of subzone B; (4) Orthotrichum speciosum-Salix arctica community In xeromesic interpolygon areas of subzone B; (5) Cochlearia groenlandica-Luzula nivalis community in hydromesic earth Mocks Of subzone B; (6) Salix arctica-Eriophorum angustifolium ssp. triste community in hygric earth hummocks of subzone 13; (7) Puccinellia angustata-Potentilla vahliana community in xeromesic non-sorted circles and bare patches of subzone Q (8) Dryas integrifolia-Carex rupestris community in xeromesic intercircle areas and vegetated patches of subzone C; (9) Braya glabella ssp. purpurascens-Dryas integrifolia community In hydromesic non-sorted circles of subzone Q (10) Dryas integrifolia-Carex aquatilis community in hydromesic intercircle areas of subzone C; and (11) Eriophorum angustifolium ssp. triste-Carex aquatilis community ill hygric intercircle areas of subzone C. The NMDS ordination displayed the vegetation types with respect to complex environmental gradients. The first axis of the ordination corresponds to a complex soil moisture gradient and the second axis corresponds to a complex geology/elevation/climate gradient. The tundra plots have a greater moss and graminoid cover than the adjacent frost-heave communities. In general, frost-heave features have greater thaw depths, more bare ground, thinner organic horizons, and lower soil moisture than the surrounding tundra. The morphology of the investigated patterned ground forms changes along the climatic gradient, with non-sorted pollygons dominating in the northernmost sites and non-sorted circles dominating, in the southern sites.

Plant species, biomass and environmental characteristics of relevés along the North America Arctic bioclimate gradient

Question: How do interactions between the physical environment and biotic properties of vegetation influence the formation of small patterned-ground features along the Arctic bioclimate gradient? Location: At 68° to 78°N: six locations along the Dalton Highway in arctic Alaska and three in Canada (Banks Island, Prince Patrick Island and Ellef Ringnes Island). Methods: We analysed floristic and structural vegetation, biomass and abiotic data (soil chemical and physical parameters, the n-factor [a soil thermal index] and spectral information [NDVI, LAI]) on 147 microhabitat releves of zonalpatterned-ground features. Using mapping, table analysis (JUICE) and ordination techniques (NMDS). Results: Table analysis using JUICE and the phi-coefficient to identify diagnostic species revealed clear groups of diagnostic plant taxa in four of the five zonal vegetation complexes. Plant communities and zonal complexes were generally well separated in the NMDS ordination. The Alaska and Canada communities were spatially separated in the ordination because of different glacial histories and location in separate floristic provinces, but there was no single controlling environmental gradient. Vegetation structure, particularly that of bryophytes and total biomass, strongly affected thermal properties of the soils. Patterned-ground complexes with the largest thermal differential between the patterned-ground features and the surrounding vegetation exhibited the clearest patterned-ground morphologies.

Gelidium densum; Gelidiaceae

Gelidium purpurascens Gardner

Biometry and body chemical eomfosition of some Japanese and Eufopean fish gpecles in culture

Dissertação de mest. em Aquacultura, Unidade de Ciências e Tecnologias dos Recursos Aquáticos, Univ. do Algarve, 1997