Aperture Pattern and Microsporogenesis in Asparagales
نویسندگان
چکیده
منابع مشابه
Aperture Pattern and Microsporogenesis in Asparagales
The aperture pattern of pollen grains is a character defined as the number, shape, and position of apertures. Although this character is highly variable in angiosperms, two states are particularly widespread. Pollen grains with one polar aperture occur frequently in basal angiosperms and monocots while tricolpate pollen is a synapomorphy of the eudicots. Many morphological characters are the re...
متن کاملConstraints and selection: insights from microsporogenesis in Asparagales.
Developmental constraints have been proposed to interfere with natural selection in limiting the available set of potential adaptations. Whereas this concept has long been debated on theoretical grounds, it has been investigated empirically only in a few studies. In this article, we evaluate the importance of developmental constraints during microsporogenesis (male meiosis in plants), with an e...
متن کاملMultiple developmental pathways leading to a single morph: monosulcate pollen (examples from the Asparagales).
BACKGROUND AND AIMS Early developmental events in microsporogenesis are known to play a role in pollen morphology: variation in cytokinesis type, cell wall formation, tetrad shape and aperture polarity are responsible for pollen aperture patterning. Despite the existence of other morphologies, monosulcate pollen is one of the most common aperture types in monocots, and is also considered as the...
متن کاملAperture pattern ontogeny in angiosperms.
Pollen grains display a wide range of variation in aperture number and arrangement (pattern) in angiosperms. Apertures are well-defined areas of the pollen wall surface that permit pollen tube germination. For low aperture numbers, aperture patterns are characteristic of the major taxonomic divisions of angiosperms. This paper presents a developmental model that explains most of the aperture pa...
متن کاملPattern Generation in Synthetic Aperture Lithography (SAL)
Synthetic Aperture Lithography (SAL) uses apparatus similar to that used in Synthetic Aperture Microscopy (SAM), as described by Mermelstein [1]. We wish to create patterns by interfering N beams of coherent light. The wavenumbers of the beams all lie on a circle in the frequency domain, typically equally spaced around the circle. If the wavelength of the monochromatic light is λ and the angle ...
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ژورنال
عنوان ژورنال: Aliso
سال: 2006
ISSN: 2327-2929
DOI: 10.5642/aliso.20062201.16