摘要:

Species of the Neotropical orchid genusStanhopeaproduce a fragrance comprising terpenoids and aromatics which attracts euglossine bee pollinators. The secretory tissue, called an osmophore, is located in the adaxial region of a sac formed near the proximal portion of the floral lip. This region is easily recognized inStanhopea oculataandS. wardiibecause it is papillate. The osmophore in these two species includes all the cells of the papillae and those directly below, that grade into fundamental tissue. Osmophore cells are more densely cytoplasmic than cells in the adjacent tissue. Numerous amyloplasts and mitochondria are seen in these cells from the earliest bud stages we examined through anthesis. Smooth and rough endoplasmic reticulum are abundant, but dictyosomes are uncommon. Mitochondria of osmophore cells appear to be distributed with no apparent pattern during bud stages, although they tend to be aligned near the plasmalemma at anthesis. Osmophore cells are highly vacuolate after anthesis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08747.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

The floral scent glands (osmophores) ofStanhopeaproduce a fragrance composed of terpenoids and aromatics which attract pollinators. The terpenoid component is composed of isoprene units synthesized via the mevalonic acid pathway. Localization of hydroxymethylglutaryl CoA synthase in the mevalonic acid pathway was achieved using a technique which elicits the formation of an electron‐dense precipitate of uranyl ferrocyanide at the point in the mevalonic acid pathway where an acetyl group from acetyl CoA is transferred to acetoacetyl CoA, releasing free CoA‐SH. Applying this technique to cells of the osmophore of 5.anfractaresulted in a precipitate between the inner and outer mitochondrial membranes, in the smooth endoplasmic reticulum, and, to a lesser extent, on the outer surface of the tonoplast membranes and between the inner and outer membranes and granal membranes of amyloplasts indicating multiple, subcellular locations for at least some enzymes in the mevalonic acid pathway. Localization of carnitine acetyltransferase by a similar technique resulted in a precipitate between the inner and outer mitochondrial membranes and in the smooth endoplasmic reticulum indicating multiple, subcellular locations for this enzyme also.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08748.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

Structural features of the pulvinus of the solar‐tracking leaf ofLavatera creticaL. that are involved in its capacity for omnidirectional and fully reversible bending in response to vectorial excitation of the lamina were studied by light‐ and scanning electron microscopy. Pulvini that had bent in the plane at right angles to the midvein were bisected along that plane and the symmetrical tissues of the expanded and contracted flanks were compared. The pulvinus contains a central vascular core and exhibits a transversely furrowed exterior. These specialized features enable the fully mature tissue of this region of the petiole to bend reversibly. The epidermis, chlorenchyma, peripheral collenchyma, and cortical parenchyma in the pulvinus form concentric, radially symmetric sheaths around the vascular core and exhibit structural features in their cell walls that would allow considerable changes in cell volume and consequently enable the omnidirectional bending of this pulvinus. Thickened wall portions of the pulvinar epidermis and peripheral collenchyma exhibit a highly specialized architecture, consisting of alternating thick and thin strips, that enhances their flexibility, while maintaining mechanical support. Cell walls of the chlorenchyma and the cortical parenchyma are thin and capable of reversible infolding. Those of the cortical parenchyma also exhibit numerous prominent transverse pit fields, indicative of anisotropic orientation of their microfibrillar lattice transverse to the pulvinar axis. This orientation is compatible with elastic deformation of the cortical parenchyma cells along the pulvinar axis. Filament‐like cytoplasmic strands were observed along the walls of pulvinar motor cells, predominantly transverse to the pulvinar axis, but their function (if any) in volume changes of these cells is unknown.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08749.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

Interspecific hybrids between woodyParthenium argentatumGray (guayule), native to Mexico and Southwest Texas, and herbaceous perennialP. hispidumvar.auriculatum(Britton) Rollins, native to the United States, were obtained successfully. The F1hybrids were intermediate for most morphological characters with the exception of the short woody stem, yellow pollen color, and the trichome morphology. Chromosome counts revealed the presence of 2n= 36 A‐chromosomes inP. argentatum.The same number of A‐chromosomes and four B‐chromosomes were found inP. hispidumvar.auriculatum.Observations of pollen mother cells showed regular meiosis in both parental species. At diakinesis, chiasmata averaged 1.12 and 1.24 per bivalent forP. argentatumandP. hispidumvar.auriculatum, respectively. Meiotic behavior of the F1hybrids was irregular. F1hybrids averaged 4.43 univalents at metaphase I, 1.95 laggards at anaphase I, and 1.62 micronuclei at the tetrad stage. The low pollen stainability (5.1%) in the F1hybrids and the limited number of viable BC1seeds (4.07%) may be reflections of the irregular meiosis. Although these primary hybrids are partially fertile, they can be used to introduce desirable characteristics ofP. hispidumvar.auriculatum, such as herbaceous perennial habit, regrowth ability, and cold tolerance into guayule.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08750.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

Leaf types in the Araceae are described and classified on the basis of their morphology and functional role. Four classes are recognized on the basis of their association with the initiation of new shoot axes, the continuation of axes, the resting of axes, or the termination and renewal of axes. The basic types are described with the terms leaf, prophyll, mesophyll, bracteole, mesobracteole, cataphyll, and blastophyll. These terms are modified with the terms monopodial, sympodial, proleptic, sylleptic, resting, flagellar, stolon, reduced, and foliage. This represents an unconventional terminology because some of the modifiers refer to the structure of the stem to which the leaves are attached, rather than to the form of the leaf itself. The intent is to draw attention to the impact of shoot organization on leaf form, and to develop a leaf terminology that will aid in describing shoot organization.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08751.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

Morphological units in the Araceae are discussed and defined. The fundamental unit is thesegment(an internode and its leaf or leaves), of which there are two basic types, the monopodial segment and the branching segment. Segments are assembled into chains to formarticles(also calledaxes), which terminate in inflorescences, and are the product of the activity of a single apical meristem. Successive articles are assembled into chains which are physiognomically unbranchedshoots.Shoot organization in the Araceae is discriminated into types on the basis of five characteristics: whether the shoot is renewed after flowering, whether renewal axes are proleptic or sylleptic, whether renewal axes develop from an axillary position, whether renewal axes have a variable or a constant number of leaves, and the number of leaves on renewal axes with a constant leaf number. The types of growth are described, illustrated, and organized into a hierarchical scheme, and a terminology is provided. A list of species representing each of the types is given.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08752.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

We have made an assessment of the genomic system of classification recently proposed for the Triticeae as a whole by Löve and for perennial Triticeae by Dewey. Limitation of genomes as a measure of similarity were discussed using examples where pairing may fail even between highly similar genomes and where morphology is a better indicator of evolutionary relationships. We found that only two of the 41 characters extracted from Löve's descriptions were described for 36 of the 37 genera, and most characters were described for less than half of the genera. Thus the descriptions were incomplete. This was further illustrated when a data matrix was created using 15 most frequent characters. A majority rule consensus tree was computed using the program BOOTM in Felsenstein's PHYLIP package, and we found that many operational taxonomic units or OTUs (the genomically defined genera) could not be resolved on the tree; homoplasy occurs throughout the tree, synapomorphies were parallel in many branches, and only one character (flowers, perfect/rudimentary) was an apomorphy leading toElymus.We recommended that all the attributes be considered a priori with equal weight without attributing supremacy to genome, thus enabling the genera to be described, circumscribed, and arranged in a meaningful system of classification.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08753.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

The histochemistry of different developmental stages of the pollen wall, aperture, and Ubisch bodies ofTriticum aestivumis examined with light and transmission electron microscopy. Various parts of the callosic envelope of the tetrad spores stain differentially. At the late tetrad stage, the probacules and the coat of pro‐Ubisch bodies are densely stained for acidic polysaccharides, protein, and neutral polysaccharides. The protectum and the core of pro‐Ubisch bodies are moderately stained. Upon release of microspores from the callosic cell envelope, the stainability for acidic polysaccharides increases in the exine and in the wall of Ubisch bodies, becoming very intense in the wall of mature pollen grains and Ubisch bodies. The stainability for neutral polysaccharides is decreased in the mature pollen wall and in the Ubisch bodies, while the stainability for protein increases. The results also indicate the probability of the presence of unsaturated lipids and the absence of free aldehydes in the pollen wall and Ubisch bodies.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08754.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

Initiation of floral primordia begins inAgalinis densiflorawith production of two lateral adaxial calyx lobe primordia followed by a midadaxial primordium, and then primordia of two abaxial calyx lobes. Initiation of three abaxial corolla lobe primordia is succeeded by that of two stamen pairs and then by primordia of two adaxial corolla lobes. The primordium of the abaxial carpel appears before the adaxial one. Except for the calyx, initiation of primordia proceeds unidirectionally from the abaxial to the adaxial side of the floral apex. Zygomorphy in the calyx, corolla, and androecium is evident during initiation of primordia and is accentuated during organogenesis. The calyx undergoes comparatively rapid organogenesis, but the inner three floral series undergo a protracted period of organogenesis. The perianth series reach maturation prior to meiosis in the anthers. Maturation of the androecium and gynoecium are postmeiotic events.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08755.x

出版商:Wiley    

年代:1987

数据来源: WILEY

摘要:

Observation of cleared ovules ofPoa secundaPresl showed that plants produce aposporous embryo sacs, and emasculation studies showed that they do not set seed without pollen. The ratio of sexual to asexual embryo sacs on a given plant does not correlate with percent stainable pollen, nor does pollen stainability correlate with meiotic regularity or with chromosome number. Percent apomictic ovules, percent pollen stainability, and regularity of meiosis all vary within a given population; they also vary if the same plant is moved from one site to another. Although there is morphological variation in the species, none of the reproductive features correlates with morphology. Pollen from any morph will stimulate seed set in any other morph, and hybrids have been produced in low frequency. Plants will also set seed using their own pollen. In its reproductive biology,P. secundaexhibits many similarities withP. pratensisL.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1987.tb08756.x

出版商:Wiley    

年代:1987

数据来源: WILEY