Waisel, Y., Eshel, A., Kafkafi, U., eds. Plant roots - the hidden half

Research on plant roots represents an exciting and intriguingfield of science. Undoubtedly, the vast major ity of researcherswithin the field are familiar with the first (1991) and second(1996) editions of this book. Since these editions were published,understanding of root biology has been advanced by using molecularbiology methods and molecular genetic tools which offer novelperspectives for the exploitation and understanding of rootstructure and root processes. The third edition of Plant roots– the hidden half includes revised and expanded informationon topics covered in the previous editions, as well as in     

Keeping up with Dobzhansky: G. Ledyard Stebbins, Jr., plant evolution, and the evolutionary synthesis

This paper explores the complex relationship between the plant evolutionist G. Ledyard Stebbins and the animal evolutionist Theodosius Dobzhansky. The manner in which the plant evolution was brought into line, synthesized, or rendered consistent with the understanding of animal evolution (and especially insect evolution) is explored, especially as it culminated with the publication of Stebbins's 1950 book Variation and Evolution in Plants. The paper explores the multi-directional traffic of influence between Stebbins and Dobzhansky, but also their social and professional networks that linked plant evolutionists like Stebbins with Edgar Anderson, Carl Epling, and the 'Carnegie team' of Jens Clausen, David Keck, and William Hiesey with collaborators on the animal side like I. Michael Lerner, Sewall Wright and L.C. Dunn and other 'architects' of the synthesis like Ernst Mayr, Julian Huxley and George Gaylord Simpson. The compatibility in training, work styles, methodologies, goals, field sites, levels of analysis, and even choice of organismic systems is explored between Stebbins and Dobzhansky. Finally, the extent to which coevolution between plants and insects is reflected in the relationship is explored, as is the power dynamic in the relationship between two of the most visible figures associated with the evolutionary synthesis.     

Ellesmeris sphenopteroides,gen. ET SP. NOV., a new zygopterid fern from the Upper Devonian (Frasnian) of Ellesmere,N.W.T., Arctic Canada

A new fern-like fossil plant is described from the lower Upper Devonian of southern Ellesmere Island, Canadian Arctic Archipelago. The plant occurs in an Archaeopteris-dominated flora preserved in the Nordstrand Point Formation (Mid-Late Frasnian) near Bird Fiord. The plant has a pinnate vegetative system with three branch orders and laminate sphenopteroid pinnules. Primary pinnae usually diverge from the main axis in distichous pairs (quadriseriate), but can depart singly (biseriate). Each primary pinna bears a basal catadromic aphlebia. Anatomically, the plant exhibits a mesarch, bipolar protostele that is ribbon- to clepsydropsoid-shaped in the main axis. Primary pinna traces are also initially bipolar and crescent-shaped, but may become four-ribbed before dividing into a pair of bipolar traces. The morphology and anatomy of this plant are nongymnospermous and are most similar to Zygopteridales (particularly Rhacophytaceae and Zygopteridaceae). The Frasnian age of Ellesmeris shows that laminated foliage had evolved in some zygopterid ferns much earlier than previously recognized. The Sphenopteris-like pinnules of Ellesmeris indicate the need for caution when attributing such a convergent foliar design to other plant groups, such as the Devonian gymnosperms.     

Willis, K.J., McElwain, J.C. The evolution of plants

This book, aimed at undergraduates, deals mostly with the informationthat can be gleaned about plant evolution from the fossil record.In some sense, its broad title is slightly misleading becauseother topics central to plant evolution such as genetic changein populations and mechanisms of speciation are hardly covered.After a brief introduction to the geological timescale, typesof fossil and how they are dated, the central six chapters formingthe bulk of the book follow a chronological journey. This takesthe reader from the appearance of the first photosynthesizers,to the colonization of the land, through to the evolution anddominance of     

Latisemenia longshania,gen. et sp. nov., a new Late Devonian seed plant from China

The earliest known ovules in the Late Devonian (Famennian) are borne terminally on fertile branches and are typically enclosed in a cupule. Among these ovules are some that have terete integumentary lobes with little or no fusion. Here, we report a new taxon, Latisemenia longshania, from the Famennian of South China, which bears cupulate ovules that are terminal as well as opposite on the fertile axis. Each ovule has four broad integumentary lobes, which are extensively fused to each other and also to the nucellus. The cupule is uniovulate, and the five flattened cupule segments of each terminal ovule are elongate cuneate and shorter than the ovule. Associated but not attached pinnules are laminate and Sphenopteris-like, with an entire or lobate margin. Latisemenia is the earliest known plant with ovules borne on the side of the fertile axis and may foreshadow the diverse ovule arrangements found among younger seed plant lineages that emerge in the Carboniferous. Following the telome theory, Latisemenia demonstrates derived features in both ovules and cupules, and the shape and fusion of integumentary lobes suggest effective pollination and protection to the nucellus. Along with other recent discoveries from China, Latisemenia extends the palaeogeographic range of the earliest seed plants.     

Arshad, M., Frankenberger, W.T. Jr. Ethylene: agricultural sources and applications

Readers of Annals of Botany will need no reminding of the importantrole that ethylene plays as a regulator of plant growth anddevelopment. This role has been translated into a     

Hymenostylium xerophilum,sp. nov., and H. gracillimum,comb. nov., two neglected European mosses and their molecular affinities

Abstract

Hymenostylium xerophilum is described as a new species from the European Alps. Molecular rps4 and ITS data support its recognition and elucidate its affinities to other species of the tribe Pleuroweisieae. It is closely related to H. gracillimum, comb. nov., which is based on the old and neglected Gymnostomum gracillimum, which replaces the recent name G. boreale. Both species share non-coloured to pale yellowish-brown rhizoids, stem central strand and indistinct sclerodermis, keeled leaves, and concave laminae in abaxial view. They differ from each other in leaf shape and several essentially quantitative characters. Sporophytes have never been found in H. xerophilum, but they are known from several localities in H. gracillimum. The former colonizes rather dry, sunny to half-shaded calcareous rocks, whereas the latter needs moist and shaded rock habitats and shows a preference for subneutral slate. At present, H. xerophilum is known only from the Alps (Austria, and a single site in Germany), where it is rather widespread in calcareous regions. H. gracillimum seems to be a distinctly rarer plant, to date known only from eight Austrian sites and one locality in Russian Karelia. Other published records under the name G. boreale have been wrongly attributed to this species. Lectotypes are designated for G. gracillimum and Gyroweisia acutifolia. A key to Hymenostylium and the genera of Pleuroweisieae in Europe is presented.

Thicker rhizoids of both species are covered with a thick, non-coloured protective layer and filled with oil-droplets and leucoplasts. They represent a subterranean secondary protonema, which plays an important role in the survival and propagation of these mosses, vital especially in the case of the non-sporulating H. xerophilum.     

Tiankengomelania guangxiense,gen. et sp. nov., a dark septate endophytic fungus,promotes the growth of the medicinal orchid Dendrobium officinale

Dendrobium officinale (Orchidaceae) is a traditional Chinese medicinal plant. Its growth is slow, however many dark septate endophytic fungi (DSEs) are considered useful to plant growth and as biocontrol agents against plant pathogens. The goals of this study were to identify a new DSE and evaluate its plant-growth promotion characteristics. Based on morphological and molecular phylogenetic evidence, a DSE fungal strain TK815 isolated from Dashiwei Tiankengs in Leye county Guangxi Province, China, was classified as a novel genus in the order Cheatothyriales, namely Tiankengomelania gen. nov. typified with T. guangxiense sp. nov. Tiankengomelania guangxiense TK815 can significantly promote the growth of D. officinale in stem length (11.25%), seedling height (16.97%), root length (10.34%), and dry weight (41.05%). This study discovered, described, and illustrated a new DSE fungus, and evaluated its biological function in contributing to the growth and production of the Chinese medicinal plant D. officinale.     

Chthoniobacter flavus gen. nov., sp. nov., the first pure-culture representative of subdivision two, Spartobacteria classis nov., of the phylum Verrucomicrobia

The phylum Verrucomicrobia is increasingly recognized as an environmentally significant group of bacteria, particularly in soil habitats. At least six subdivisions of the Verrucomicrobia are resolved by comparative analysis of 16S rRNA genes, mostly obtained directly from environmental samples. To date, only two of these subdivisions (1 and 4) have characterized pure-culture representatives. We have isolated and characterized the first known pure-culture representative of subdivision 2. Strain Ellin428 is an aerobic heterotrophic bacterium that is able to grow with many of the saccharide components of plant biomass but does not grow with amino acids or organic acids other than pyruvate. Cells are yellow, rod-shaped, nonmotile, and gram-stain negative, and they contain peptidoglycan with direct cross-linkages of the A1 gamma meso-Dpm type. The isolate grows well at 25 degrees C on a variety of standard biological media, including some used in the routine cultivation of bacteria from soil. The pH range for growth is 4.0 to 7.0. Low levels of menaquinones MK-10 and MK-11 were detected. The major cellular fatty acids are C(14:0), a-C(15:0), C(16:1 omega 7c), and/or 2OH i-C(15:0), and C(16:0). The G+C content of the genomic DNA is 61 mol%. We propose a new genus and species, Chthoniobacter flavus gen. nov., sp. nov., with isolate Ellin428 as the type strain, and a new class for the subdivision to which it belongs, Spartobacteria classis nov. Environmental sequences indicate that the class Spartobacteria is largely represented by globally distributed, abundant, and active soil bacteria.     

Dris, R., Abdelaziz, F.H. and Jain, S.M. Plant nutrition: growth and diagnosis

Is research on plant mineral nutrition still necessary wheninorganic fertilizers are readily available? The simple answeris ‘yes’! The use of inorganic fertilizers depletesnatural resources and can impose a heavy financial and environmentalcost. For example, reserves of rock phosphate (the primary sourceof P for fertilizers) are diminishing whilst the production,transport     

Le risorse genetiche vegetali. I. Principi,realtà, problemi

Abstract

Plant genetic resources. I. The problem of the conservation of plant genetic resources emerges from the examination of the consequences of the genetic erosion and of the destruction of genetic variability, which provoke decline and disappearance of plant species, of agricultural value too.

Information are given on species and primitive or local varieties desappeared or threatened by destruction, on the emergency situation already existing in various areas, including also centres of origin and diversification, and on the risks of a plant breeding work manipulating a reduced genetic basis.

Thus, it is crucial to collect and maintain an abundant germplasm of the main crops, as well as of those species of minor agricultural importance. It is wise also to pay attention to plant species of potential value as new food crops or as sources for industrial pharmaceutical or pesticide products or other products with specific chemical properties.

Finally, the author underlines the urgent need, for the future progress of agriculture and for the benefit of the mankind, to safeguard plant genetic resources, which must be considered as essential part of the problem of the conservation of the nature and of its resources.     

Parasitism of the herbivore Pieris brassicae L. (Lep., Pieridae) by Cotesia glomerata L. (Hym., Braconidae) does not benefit the host plant by reduction of herbivory

Models of tritrophic interactions often imply that attraction of herbivore natural enemies by the plant constitutes a defence. Parasitoid attack on herbivores is assumed to result in a reduction in herbivory and/or an increase in plant fitness. Coupled with the active involvement of the plant in producing signals, this can be seen as indirect mediation of wound-induced defence. The assumption that parasitism of Pieris brassicae L. by the parasitoid Cotesia glomerata L. reduces leaf consumption of cabbage is tested. The effect of parasitism on the growth and feeding rates of P. brassicae larvae compared to unparasitized larvae. Either the defensive mechanism, if it exists, is more subtle, or the natural enemy is using an incidental chemical produced as a by-product of the herbivores feeding action as a cue for host-finding, with no increaction effects. This has implications for the study of tritrophic interactions, particularly in the context of agricultural systems and the assumption that in IPM strategies, parasitoids are a plant benefit.     

Ultrastructural description of a new chytrid genus of caecum anaerobe, Caecomyces equi gen. nov., sp. nov., assigned to the Neocallimasticaceae

Vegetative and reproductive stages of Caecomyces equi gen. nov., sp. nov. isolated from the horse caecum were examined by light and electron microscopy. This organism, which is similar to isolates known as Sphaeromonas communis, produces uniflagellate, uninucleate zoospores whose perikinetosomal structures, i.e. circumflagellar ring, spur, struts and scoop, are similar in many respects to those described in species of Neocallimastix. Microtubular roots extend basally from the spur and associate with hydrogenosomes and the nucleus. Another group of microtubules radiates laterally in a fan-shaped array close to the plasmalemma. Zoospores encyst, shedding their flagella with basal bodies, and germinate to diglobular thalli. Either coralloid or bulbous rhizoids form in plant material, but only the latter in axenic culture. Incipient zoospores are produced from a multinucleate eucarpic thallus and devlop within cleavage vacuoles containing flagella. An isolate from the cow rumen was found to be similar to C. equi in morphology and zoospore ultrastructure. On the basis of zoospore ultrastructure, we assign the new genus to the Neocallimasticaceae of the order Spizellomycetales. Organisms previously described as Sphaeromonas communis and Piromonas communis are renamed Caecomyces communis and Piromyces communis and assigned to the same family.     

Cylindrocladium angustatum sp. nov., a new leaf spot pathogen ofTillandsia capitata from Florida, U.S.A.

Cylindrocladium angustatum is described as a new species fromTillandsia introduced with plant material into the U.S.A. from Central America. Koch's postulates are established to prove its pathogenicity to this host. The species is compared with and distinguished fromC. heptaseptatum andC. rumohrae based on morphology, cultural characteristics and phylogenetic analysis of sequence data of the beta-tubulin gene.     

A new species, Embellisia astragali sp. nov., causing standing milk-vetch disease in China

A new species, Embellisia astragali sp. nov., is described from necrotic leaves, petioles and stems of Astragalus adsurgens in China. The morphology of E. astragali is compared and contrasted to that of four similar species, E. abundans, E. oxytropis, E. phragmospora and E. telluster. The fungus grew intercellularly in stems and leaf blades and intracellularly in leaves. It was isolated from most sources of seeds at frequencies of 0.1-44.6%. Growth rates of colonies on potato-carrot agar, potato-dextrose agar, wheat hay decoction (WHDA) and V8 at 25 C were 0.48, 0.32, 0.68 and 0.27 mm d(-1), respectively. The optimal temperature for colony growth on WHDA was 20-25 C, and no growth was measured above 30 C. Five week old standing milk-vetch seedlings were inoculated with E. astragali by dipping whole roots and pruned roots in a conidial suspension and pouring the suspension onto the soil surface in which two seedlings had been planted. After 20 wk 66.5%, 62.1% and 85.0% plants were diseased and 24.1%, 20.7% and 17.5% plants were dead, respectively. Symptoms included the development of more side shoots with small, curved, necrotic and yellowed young leaves, plant stunting, reddish brown lesions, stem browning, dieback, shoot blight, crown rot, root black rot and plant death. This is first report of a pathogenic Embellisia on legumes.     

Candida alocasiicola sp. nov., Candida hainanensis sp. nov., Candida heveicola sp. nov. and Candida musiphila sp. nov., novel anamorphic, ascomycetous yeast species isolated from plants

In a taxonomic study on the ascomycetous yeasts isolated from plant materials collected in tropical forests in Yunnan and Hainan Provinces, southern China, four strains isolated from tree sap (YJ2E(T)) and flowers (YF9E(T), YWZH3C(T) and YYF2A(T)) were revealed to represent four undescribed yeast species. Molecular phylogenetic analysis based on the large subunit (26S) rRNA gene D1/D2 domain sequences showed that strain YJ2E(T) was located in a clade together with Candida haemulonii and C. pseudohaemulonii. Strain YF9E(T) was most closely related to C. azyma and strain YWZH3C(T) to C. sorbophila and C. spandovensis. Strain YYF2A(T) was clustered in a clade containing small-spored Metschnikowia species and related anamorphic Candida species. The new strains differed from their closely related described species by more than 10% mismatches in the D1/D2 domain. No sexual states were observed for the four strains on various sporulation media. The new species are therefore assigned to the genus Candida and described as Candida alocasiicola sp. nov. (type strain, YF9E(T) = AS 2.3484(T) = CBS 10702(T)), Candida hainanensis sp. nov. (type strain, YYF2A(T) = AS 2.3478(T) = CBS 10696(T)), Candida heveicola sp. nov. (type strain, YJ2E(T) = AS 2.3483(T) = CBS 10701(T)) and Candida musiphila sp. nov. (type strain, YWZH3C(T) = AS 2.3479(T) = CBS 10697(T)).     

Seimatoantlerium tepuiense gen. nov., a unique epiphytic fungus producing taxol from the Venezuelan Guyana.

Seimatoantlerium gen. nov., type species, S. tepuiense sp. nov. is proposed for an acervular fungus producing 4-septate, holoblastic conidia with 6-8 unbranched, apical appendages that dehisce as an appendage apparatus and also commonly possessing one or two exogenous basal appendages as well as a pedicel. It is compared with Seimatosporium, Seimatosporiopsis, and other genera. It is epiphytic on Maguireothamnus speciosus, a rubiaceous plant endemic to the tepuis of southeastern Venezuela. It produces the anti-oomycetous anticancer compound, taxol, as shown by immunological and spectroscopic methods. Taxol production is discussed relative to the ability of this fungus to exist in an extremely moist ecosystem, as well as to its relationship to other plant associated fungi.     

Clevelandodendron ohioensis,gen. et sp. nov., a slender upright lycopsid from the late Devonian Cleveland Shale of Ohio

Clevelandodendron ohioensis Chitaley & Pigg gen. et sp. nov. is an almost entire lycopsid plant known from a single compressed specimen from the Cleveland Shale member of the Upper Devonian Ohio Shale. This unique specimen is 125 cm long, consisting of an unbranched, slender, monopodial axis with a partially preserved plant base bearing thick appendages at one end, and a compact, terminal ovoid bisporangiate strobilus at the other. The stem is 2 cm wide for most of its length. Visible on the decorticated stem surface are helically arranged, elongate leaf traces and laterally compressed, slender leaves along the stem margin. The plant base bears 4-6 thick appendages. The terminal strobilus is compact, ovoid, 9 cm long and up to 6 cm wide, morphologically similar to those of some Lepidodendrales, and bears helically arranged sporophyll/sporangium complexes with narrow bases and distal laminae up to 18 mm long, turned upward. Megaspores are 320-360 μm, trilete and laevigate, lacking a gula; microspores are 30-42 μm, trilete, indistinctly punctate and possibly assignable to Calamospora or Punctatisporites. Clevelandodendron demonstrates that slender unbranched lycopsids with an isoetalean plant habit similar to the Carboniferous genera Chaloneria and Sporangiostrobus and Triassic Pleuromeia-like forms were present as early as the Late Devonian. The early occurrence of this unique habit suggests that diversification within the isoetalean clade sensu Rothwell and Erwin (including both Isoetales and Lepidodendrales) was well established prior to the Carboniferous.     

苜蓿、草木樨、锦鸡儿根瘤菌的表型多样性分析

选用48株分离自新疆和内蒙的苜蓿属、草木樨属、锦鸡儿属植物的根瘤菌菌株, 进行了营养利用、抗生素抗性、耐逆性和酶活性测定等133个表型性状分析。发现分离自同种寄主植物的根瘤菌由于地理来源的不同而存在着较大的多样性。通过数值分类,各已知种分别聚群,41株未知菌在85%的相似水平上分为3个不同于已知种的群。群1的菌株主要分自苜蓿,群2的菌株主要分自草木樨,群3的菌株分自锦鸡儿,XJ96 333(寄主为Melilotus)作为1个单株在84%的相似水平上和群1聚在一起。NM 020(寄主为Caragana)在88%的相似水平上和R.leguminosarum聚在一起; NM 183、NM 218(寄主为Caragana)在86%的相似水平上和S.fredii聚在一起; 在67%的相似水平上, XJ96 482(寄主为Medicago sativa)和其它所有供试菌株聚群。群1、2、3的所有菌株能在含2.0%(340 mM)NaCl的YMA培养基上、pH 9.0的YMA培养基、40℃的高温下生长; 群3的所有菌株还能在含3.0%(510 mM)NaCl的YMA培养基上生长;群1中90%的菌株和群2、3的所有菌株能在10℃的低温下生长。 表明群1、2、3的菌株具有较强的耐盐碱、耐高低温的特性。和已知种S.meliloti具有相同寄主的群1、群2在85%相似水平上未和S.meliloti聚群,表现了这两群菌在表型上的多样性。