Tagged: morphogenesis

A diagram of cell formation

Subsidiary cell formation in Poaceae stomatal complexes

Polarisation and asymmetrical division generating the Poaceous subsidiary cells constitutes a very attractive model for the study of local intercellular stimulation. Auxin operates as an inductive stimulus while PIN auxin carriers and reactive oxygen species seem to facilitate signal transduction. Specific cell wall components and the SCAR/WAVE complex are emerging as the earliest polarization factors described so far. Other proteins such as the leucine-rich receptor-like kinases PAN1 and PAN2, Rho-like GTPases of plants, the phosphatidyl-inositol-3-kinase and phospholipases C and D also participate in the transmission of the extrinsic signal that polarizes the asymmetric division. Apostolakos et al. summarize findings derived...

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A diagram of the paper

ARP2/3 complex links cell wall assembly and auxin distribution

The protein complex ARP2/3 is responsible for nucleating actin, and its loss results in multiple defects in young seedlings of Arabidopsis thaliana. Sahi et al. show that plants lacking the ARP2/3 complex have defects associated with cell wall synthesis. Mature tissues of inflorescence stems contain less cellulose and more homogalacturonan, cell walls are thinner, and lignification is altered. Stems of mutant plants have reduced basipetal auxin transport and a changed auxin influx carrier (AUX1) expression pattern. Since cell wall composition and auxin transport are functionally connected, morphogenetic defects may be explained by ARP2/3 control of cell wall synthesis and/or auxin...

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The effect of geometry on patterning and morphogenesis

Two-stage patterning dynamics in conifer cotyledon morphogenesis

Conifers form a single whorl of multiple cotyledons (embryonic leaves), unlike monocots and dicots. Polar transport of the hormone auxin affects outgrowth of distinct cotyledons, but not the radial positioning of the whorl or the within-whorl spacing between cotyledons. Holloway et al. present a mathematical model of growth regulator patterning accounting for the response to auxin transport disruption, the stability of the single whorl over the large variation in embryo size, the linear relation between cotyledon number and embryo size, and early cotyledon morphogenesis. The conifer mechanism may apply more generally to single whorls of multiple primordia in other plants.

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Passiflora foetida

Space matters in flower development

Flower meristems have the capacity to expand throughout their development, generating space for new structures. Claßen-Bockhoff and Meyer demonstrated this by the example of corona formation in passionflowers. The conspicuous corona elements arise as ‘de novo’ structures with ongoing receptacle expansion. Open space obviously induces their formation as a self-regulating process. Considering spatio-temporal conditions widens our view on flower meristems, clarifies homology and allows new interpretations in combination with molecular, phylogenetic and morphogenetic data.

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Image: Wikimedia Commons.

Turing’s centenial flowers

When flowers are mentioned in the context of Alan Turing (OBE, FRS, maths genius, tortured soul, ‘an enigma inside a colossus’, and one of the main members of the group of Bletchley Park code-breakers who were instrumental in decoding the Nazis’ Enigma code and thereby credited with considerably shortening the Second World War and saving many thousand of lives), the more knowledgeable may think of Tommy Flowers. Tommy Flowers (MBE) worked alongside Turing and designed the Colossus computer used at Bletchley to help solve encrypted German messages. But this item concerns flowers of a more botanical kind: Sunflowers. Amongst Turing’s...

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