The southernmost myco-heterotrophic plant, Arachnitis uniflora: root morphology and anatomy

Root morphology and anatomy of the myco-heterotrophic Arachnitis uniflora (Corsiaceae) were studied in relation to their association with a Glomus species (Glomeromycota). The mycorrhizal features were studied in three distinctive stages of development: (i) shoot and flower restricted to a small, underground bud; (ii) shoot and flower bud up to 1.5 cm; and (iii) shoot and flower already withered. The hyphae penetrate through and between the epidermal and exodermal cells; the exodermis and outer cortical cells become colonized in an inter- and intracellular manner, with some coils being formed in these layers. The fungi colonize the middle cortex, where intracellular vesicles in bundles are abundant. Arbuscules are formed profusely at very early stages of development, while in older stages they almost disappear and abundant vesicles are formed. Except for some details, the pattern of root colonization corresponds to a Paris-type. Presence of storage substances (starch and oil) also was recorded. Starch is produced and stored within root cells, mainly in the outer and inner root cortex. In senescent stages, plant and fungal tissues collapse.     

Uberon, an integrative multi-species anatomy ontology

We present Uberon, an integrated cross-species ontology consisting of over 6,500 classes representing a variety of anatomical entities, organized according to traditional anatomical classification criteria. The ontology represents structures in a species-neutral way and includes extensive associations to existing species-centric anatomical ontologies, allowing integration of model organism and human data. Uberon provides a necessary bridge between anatomical structures in different taxa for cross-species inference. It uses novel methods for representing taxonomic variation, and has proved to be essential for translational phenotype analyses. Uberon is available at http://uberon.org.     

Building a cell and anatomy ontology of Caenorhabditis elegans

We are endowed with a rich knowledge about Caenorhabditis elegans. Its stereotyped anatomy and development has stimulated research and resulted in the accumulation of cell-based information concerning gene expression, and the role of specific cells in developmental signalling and behavioural circuits. To make the information more accessible to sophisticated queries and automated retrieval systems, WormBase has begun to construct a C. elegans cell and anatomy ontology. Here we present our strategies and progress.     

The RNA structure alignment ontology

Multiple sequence alignments are powerful tools for understanding the structures, functions, and evolutionary histories of linear biological macromolecules (DNA, RNA, and proteins), and for finding homologs in sequence databases. We address several ontological issues related to RNA sequence alignments that are informed by structure. Multiple sequence alignments are usually shown as two-dimensional (2D) matrices, with rows representing individual sequences, and columns identifying nucleotides from different sequences that correspond structurally, functionally, and/or evolutionarily. However, the requirement that sequences and structures correspond nucleotide-by-nucleotide is unrealistic and hinders representation of important biological relationships. High-throughput sequencing efforts are also rapidly making 2D alignments unmanageable because of vertical and horizontal expansion as more sequences are added. Solving the shortcomings of traditional RNA sequence alignments requires explicit annotation of the meaning of each relationship within the alignment. We introduce the notion of “correspondence,” which is an equivalence relation between RNA elements in sets of sequences as the basis of an RNA alignment ontology. The purpose of this ontology is twofold: first, to enable the development of new representations of RNA data and of software tools that resolve the expansion problems with current RNA sequence alignments, and second, to facilitate the integration of sequence data with secondary and three-dimensional structural information, as well as other experimental information, to create simultaneously more accurate and more exploitable RNA alignments.     

Substances of plant flowering

The investigation of the hormonal nature of plant flowering in connection with their photoperiodic reaction has shown that flowering depends on a bicomponental system of hormones, gibberellins regulating stem formation and growth and substances of the anthesin type regulating flower formation. In agreement with the division of the photoperiodic reaction into a leaf and a stem phase the study of the internal factors acting on plant flowering was carried out by means of leaf and stem (apex, bud and callus) models. The results obtained from work with leaf models proved the presence of two groups of hormones of flowering in plants. The data obtained from the application of stem models pointed to the localization of the action of gibberellin and anthesin in different zones of the shoot apices and characterized the potential capacity for flower formation of isolated callus tissue of neutral and photoperiodically sensitive species.     

Identification of flowering genes in strawberry, a perennial SD plant

Background  

We are studying the regulation of flowering in perennial plants by using diploid wild strawberry (Fragaria vesca L.) as a model. Wild strawberry is a facultative short-day plant with an obligatory short-day requirement at temperatures above 15°C. At lower temperatures, however, flowering induction occurs irrespective of photoperiod. In addition to short-day genotypes, everbearing forms of wild strawberry are known. In 'Baron Solemacher' recessive alleles of an unknown repressor, SEASONAL FLOWERING LOCUS (SFL), are responsible for continuous flowering habit. Although flower induction has a central effect on the cropping potential, the molecular control of flowering in strawberries has not been studied and the genetic flowering pathways are still poorly understood. The comparison of everbearing and short-day genotypes of wild strawberry could facilitate our understanding of fundamental molecular mechanisms regulating perennial growth cycle in plants.     

Identification of myosin in a flowering plant, Egeria densa.

A myosin-like protein was extracted and partially purified from a flowering plant, Egeria densa. It had no p-nitrophenyl phosphatase activity, but exhibited EDTA(K+)-ATPase [EC 3.6.1.3] activity at high ionic strength. Its molecular weight as estimated by gel filtration was 4-5 X 10(5). The presence of a heavy chain (MW = about 1.8 X 10(5)) was indicated by SDS-gel electrophoresis. Egeria myosin aggregated in an environment of low ionic strength and formed bipolar filaments. It bound with skeletal muscle F-actin with a periodicity of 40 nm.     

Studies on the growth and flowering of a short-day plant,Wolffia microscopica

Summary As found earlier, supply of EDTA was obligatory for both flowering and satisfactory vegetative growth in Wolffia microscopica. It is now shown that the metal affecting growth and flowering is most probably iron. Omission of Fe but not of Cu, Zn, Mn and B from the medium markedly affects vegetative growth. There exists also a strong interaction between EDTA and Fe, one being largely inactive in the absence of the other. When Fe-EDDHA is substituted for Fe-citrate and EDTA in the medium, no great effect is seen in vegetative growth, but flowering takes place even under continuous light. Studies with ⁵⁹Fe show that, in the medium containing Fe-EDDHA, Fe uptake is stimulated several-fold; this is apparently associated with the flowering condition.Abbreviations EDTA ethylenediaminetetraacetic acid - EDDHA ethylenediamine-di-o-hydroxyphenylacetic acid     

Oryzalin-induced chromosome doubling in triploid Populus and its effect on plant morphology and anatomy

Plant Cell, Tissue and Organ Culture (PCTOC) - Populus is an important economical woody species due to its fast growth. In vitro induction of hexaploidy and investigation of morphological and...     

Photoperiodic control of flowering in Dactylis glomerata, a true short-long-day plant

Flowering requirements of three Scandinavian cultivars of Dactylis glomerata L. have been studied in controlled environments. At temperatures ranging from 9 to 21°C optimal flowering required 10 weeks of exposure to short days (SD) followed by exposure to long days (LD). Only a few plants flowered in continuous LD and no primary induction took place in any daylength at 24 or 27°C. However, at a temperature of 3°C primary induction occurred also in 24 h LD, but more than 20 weeks of treatment were required for 100% flowering. The critical photoperiod for secondary induction was about 12–13 h, depending on the latitude of origin of the cultivar. A critical number of 12 to 16 LD cycles was required for 100% flowering, although some plants flowered after only 4 LD. A high proportion of viviparous proliferation resulted from marginal LD induction. Initiation of floral primordia did not take place in SD but required a transition from SD to LD. These results demonstrate that D. glomerata is a true short-long-day plant.     

Sperm movement during double fertilization of a flowering plant,Phaius tankervilliae

Fertilization in flowering plants involves the fusion of one sperm with the egg cell and a second sperm with the central cell. In the Nun orchid, Phaius tankervilliae (Aiton) Bl., the pollen tube deposits two sperms in the "cytoplasmic mass" of the degenerating synergid. Initially both sperms stay close together. Soon afterwards, the two sperms undergo migration. The leading sperm migrates towards the central cell, while the other sperm moves laterally towards the egg cell. The degenerated synergid cytoplasmic content fills in the available space between the central cell and the egg cell, forming the actin coronas. Due to the high actin content, the bright fluorescence initially prevents the visualization of cellular details. With the subsequent reduction in fluorescence, actin staining reveals that the two sperms are pear-shaped with pointed tails. As the sperms approach their respective target cells, cellular extensions form near the point of sperm entry in both the egg cell and the central cell. These structures appear to aid in the cell fusion process. The morphological and structural features observed provide evidence that the process of double fertilization requires the active participation of not only the two sperms but also the egg cell and the central cell.     

Molecular phylogenetic position of podostemaceae, a marvelous aquatic flowering plant family

Podostemaceae are aquatic herbs and are famous for their anomalous vegetative morphology, occurring only in rapids. Because of its peculiar morphology, there were no established theory nor accepted opinion on the phylogenetic position. Especially, Cusset and Cusset (1988) proposed the new class, Podostemopsida beside the Magnollopsida and Liliopsida. We, therefore, consequences extensive and detailled analyses using nucleotide sequences ofrbcL genes for two genera and three species of the family together with many representatives of the families of flowering plants to determine the closest ally. The conclusion was that the Crassulaceae is a sister group to the Podostemaceae.     

Induction of flowering by cytokinins in a short-day plant, Lemna paucicostata

Lemna paucicostata, normally a short-day plant, can be inducedto flower under long-day conditions by providing a cytokininin a medium containing a high level of ferric citrate (5 x 10^–4M).Interestingly, when a cytokinin and EDDHA are present togetherin the medium, flowering is induced even at low levels of iron(10^–5 and 5 x 10^–5M ferric citrate). However, inthe absence of a cytokinin, flowering takes place only undershort days. (Received September 30, 1968; )     

Vegetative anatomy and morphology of Amentiferae

Some of the important vegetative characters of amentiferous families described in research papers concerned with interfamilial relationships and published since 1947–1948 are briefly summarized. Important conclusions by the writers are also reviewed. Thus, Bataceae are considered derivatives of the Centrospermae ; Betulaceae, Casuarinaceae, and Ulmaceae are hamamelidaceous derivatives; Garryaceae and Cornaceae are closely related; and Julianiaceae and Anacardiaceae are plausible relatives. A more extensive tabulation of vegetative characters of essentially all amentiferous and ranalean families and Dilleniaceae is also presented, and the data are utilized to compare the percentages of advanced and primitive characters in these same taxa. The logic for considering trends whose evolutionary directions were initiated previous or incidental to angiospermous origin as more valid than other evolutionary trends is offered. The following principal conclusions are based upon the analysis of the tabulation: (1) the Amentiferae have sufficient advanced vegetative characters to preclude consideration of them as earliest angiosperms or their direct derivatives unless a large number of primitive features of other sorts offers strong counter evidence; (2) they also have sufficient primitive characters to discount the concept that they are highly evolved; (3) most Amentiferae clearly possess many more advanced vegetative characters than do most Magnoliales, Laurales, Trochodendrales, or Dilleniaceae ; and (4) relationships of several Amentiferae to various, unrelated angiospermous families have been demonstrated.