Pattern Formation in Plant Tissues

Sachs, Tsvi

doi:10.1017/cbo9780511574535

Cited by 288 publications

(200 citation statements)

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“…During establishment of the interfascicular cambium, according to the signal flow canalization hypothesis (32), there should be tangential͞lateral transport of IAA from the existing primary vascular bundles into the adjacent parenchyma. This flow, it is postulated, should eventually lead to the dedifferentiation of parenchyma into cambial cells.…”

Section: Discussionmentioning

confidence: 99%

Polar auxin transport in the wood-forming tissues of hybrid aspen is under simultaneous control of developmental and environmental signals

Schrader

Baba

May

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

227

204

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Recent research has highlighted the importance of auxin concentration gradients during plant development. Establishment of these gradients is believed to involve polar auxin transport through specialized carrier proteins. We have used an experimental system, the wood-forming tissue of hybrid aspen, which allows tissue-specific expression analysis of auxin carrier genes and quantification of endogenous concentrations of the hormone. As part of this study, we isolated the putative polar auxin transport genes, PttLAX1-PttLAX3 and PttPIN1-PttPIN3, belonging to the AUX1-like family of influx and PIN1-like efflux carriers, respectively. Analysis of PttLAX and PttPIN expression suggests that specific positions in a concentration gradient of the hormone are associated with different stages of vascular cambium development and expression of specific members of the auxin transport gene families. We were also able demonstrate positive feedback of auxin on polar auxin transport genes. Entry into dormancy at the end of a growing season leads to a loss of auxin transport capacity, paralleled by reduced expression of PttLAX and PttPIN genes. Furthermore, data from field experiments show that production of the molecular components of the auxin transport machinery is governed by environmental controls. Our findings collectively demonstrate that trees have developed mechanisms to modulate auxin transport in the vascular meristem in response to developmental and environmental cues.

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Section: Discussionmentioning

confidence: 99%

Polar auxin transport in the wood-forming tissues of hybrid aspen is under simultaneous control of developmental and environmental signals

Schrader

Baba

May

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

227

204

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“…Sachs (15), building on experiments, proposed that new vascular strands form as the draining paths of auxin. His empirically derived Canalization Hypothesis holds that improved transport along a path enlarges a path's capacity.…”

Section: Motivation and Assumptionsmentioning

confidence: 99%

A constant production hypothesis guides leaf venation patterning

Dimitrov

Zucker

2006

Proc. Natl. Acad. Sci. U.S.A.

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We propose a theoretical mechanism that enables the elaboration of veins to supply distant cells during leaf development. In contrast to the more standard view that a signal (e.g., auxin) is produced at isolated sites to stimulate growth, we determine the consequences of the hypothesis that auxin is produced at a constant rate in every cell. High concentration sites for auxin emerge naturally in a reaction-diffusion model, together with global information about leaf shape and existing venation. Because the global information is encoded as auxin concentration and its gradient, those signals provide individual cells with sufficient information to determine their own fate. Unlike other models, a single substance suffices for the reaction-diffusion at early, but not initial, stages of development. Neither complex interactions nor predetermination are necessary. We predict angiosperm areolation patterns in simulation, and our model further implies the Sachs Canalization Hypothesis and resolves a dilemma regarding the role of auxin in cell growth.canalization hypothesis ͉ emergent behavior ͉ reaction-diffusion I solated sites of high auxin concentration have been observed in developing leaves (1), and it has been assumed that auxin production is dominant there. However, evidence (1, 2) is emerging that production may be present at other sites. We demonstrate that discrete regulated sites of synthesis need not exist to develop a spatial pattern of discrete responses. Formally, our ''constant production hypothesis'' holds that auxin is produced in all cells at the same constant rate. Mathematical analysis of a schematic reaction diffusion model indicates that high concentration sites emerge, which agrees with observations (1) but also shows that distributions carry rich information about the geometry of the leaf and its venation. This information can be interpreted locally as a signal at the cell level, thereby providing global cues. The concentration together with the gradient of concentration have substantial predictive power about vein formation (Fig. 1). Signals for initiating differentiation are readily available locally, removing the need for complex intercellular communication.Our model differs from others that focus on local phenomena (4-6). We seek to articulate those global pattern features that emerge from purely local phenomena. Such structural questions on a larger scale have, to our knowledge, only been considered in the work of Meinhardt and Gierer (7,8) and, more recently, in the empirical models by Mündermann et al. (9) and Feugier et al. (10). We show, contrary to Meinhardt (8) and certain current opinion (11,12), that a single substance traveling purely by diffusion [or its equivalent (13)] is theoretically sufficient as a basis for a mechanistic model of venation patterning when it is uniformly and constantly produced (cf. ref. 10). Motivation and AssumptionsWe demonstrate how simple local behaviors, occurring simultaneously and independently at the cell level, can give rise to complex global pattern...

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“…Genes are known to be involved both during the formation of the visible shoot meristem and in its maintenance (Barton and Poethig, 1993;Clark et al, 1996;Laux Heredity et al, 1996;Kerstetter and Hake, 1997) and to be differentially active over its expanse (Fleming et al, 1993;Pien et al, 2001).The transformation of a cellular cytoplasmic element or region into a multicellular region with the capacity for initiation of organs, as well as considerable control over their shape and/or rate of development (Steeves and Sussex, 1989;Lyndon, 1990;Sachs, 1991) probably involves many genes. An interaction between maternal and paternal cytoplasmic components which initially 'fixes' or determines the polarity of the zygote (Lyndon, 1990), perhaps in a non-specific way in most known cases, but in a highly specific way in this case, seems a suitable postulate here.…”

Section: Discussionmentioning

confidence: 99%

Evidence for cytoplasmic inheritance of a developmental organizer affecting growth habit and leaf shape in Antirrhinum majus

Bergbusch¹

2002

Heredity

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A cross between two distinct, true-breeding plants of Antirrhinum majus L. showed an unexpected pattern of inheritance of growth habit in the F2, which was extended to both growth habit and leaf shape in the F3 generation of all the plants traced further. All the F3 families, offspring of individual F2 plants, were very uniform for both growth habit and leaf shape traits but differed distinctly from each other in these respects. The backcrosses of selected F3 and F4 families to the original parents in the cross did not segregate for the distinctive family phenotypes. This led to the postulate

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Pattern Formation in Plant Tissues

Cited by 288 publications

References 0 publications

Polar auxin transport in the wood-forming tissues of hybrid aspen is under simultaneous control of developmental and environmental signals

Polar auxin transport in the wood-forming tissues of hybrid aspen is under simultaneous control of developmental and environmental signals

A constant production hypothesis guides leaf venation patterning

Evidence for cytoplasmic inheritance of a developmental organizer affecting growth habit and leaf shape in Antirrhinum majus

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