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C. W. Kilmister

Bio: C. W. Kilmister is an academic researcher. The author has contributed to research in topics: Phyllotaxis. The author has an hindex of 1, co-authored 1 publications receiving 196 citations.
Topics: Phyllotaxis

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Journal ArticleDOI
20 Nov 2003-Nature
TL;DR: It is shown that proteins involved in auxin transport regulate phyllotaxis, and data indicate that auxin is transported upwards into the meristem through the epidermis and the outermostMeristem cell layer.
Abstract: The regular arrangement of leaves around a plant's stem, called phyllotaxis, has for centuries attracted the attention of philosophers, mathematicians and natural scientists; however, to date, studies of phyllotaxis have been largely theoretical. Leaves and flowers are formed from the shoot apical meristem, triggered by the plant hormone auxin. Auxin is transported through plant tissues by specific cellular influx and efflux carrier proteins. Here we show that proteins involved in auxin transport regulate phyllotaxis. Our data indicate that auxin is transported upwards into the meristem through the epidermis and the outermost meristem cell layer. Existing leaf primordia act as sinks, redistributing auxin and creating its heterogeneous distribution in the meristem. Auxin accumulation occurs only at certain minimal distances from existing primordia, defining the position of future primordia. This model for phyllotaxis accounts for its reiterative nature, as well as its regularity and stability.

1,420 citations

Journal ArticleDOI
TL;DR: The results show that auxin is required for and sufficient to induce organogenesis both in the vegetative tomato meristem and in the Arabidopsis inflorescence meristsem, and it is proposed that Auxin determines the radial position and the size of lateral organs but not the apical–basal position or the identity of the induced structures.
Abstract: Leaves originate from the shoot apical meristem, a small mound of undifferentiated tissue at the tip of the stem. Leaf formation begins with the selection of a group of founder cells in the so-called peripheral zone at the flank of the meristem, followed by the initiation of local growth and finally morphogenesis of the resulting bulge into a differentiated leaf. Whereas the mechanisms controlling the switch between meristem propagation and leaf initiation are being identified by genetic and molecular analyses, the radial positioning of leaves, known as phyllotaxis, remains poorly understood. Hormones, especially auxin and gibberellin, are known to influence phyllotaxis, but their specific role in the determination of organ position is not clear. We show that inhibition of polar auxin transport blocks leaf formation at the vegetative tomato meristem, resulting in pinlike naked stems with an intact meristem at the tip. Microapplication of the natural auxin indole-3-acetic acid (IAA) to the apex of such pins restores leaf formation. Similarly, exogenous IAA induces flower formation on Arabidopsis pin-formed1-1 inflorescence apices, which are blocked in flower formation because of a mutation in a putative auxin transport protein. Our results show that auxin is required for and sufficient to induce organogenesis both in the vegetative tomato meristem and in the Arabidopsis inflorescence meristem. In this study, organogenesis always strictly coincided with the site of IAA application in the radial dimension, whereas in the apical–basal dimension, organ formation always occurred at a fixed distance from the summit of the meristem. We propose that auxin determines the radial position and the size of lateral organs but not the apical–basal position or the identity of the induced structures.

949 citations

Journal ArticleDOI
TL;DR: This work proposes a rice developmental staging system divided into three main phases of development: seedling, vegetative, and reproductive, and assigns rice growth stages based on discrete morphological criteria to result in unambiguous growth-stage determination.
Abstract: The large area of rice (Oryza sativa L) production worldwide is critical to the well being of large numbers of the world's people Yet for rice, the most important single plant species for human nutrition, there is not a widely used growth staging system Despite good points of the published rice growth staging systems, none has been used widely for describing rice growth and development Consequently, an objective growth staging system with enumeration adapted to cumulative leaf number (CLN) would improve communication among scientists, farmers, and educators We propose a rice developmental staging system divided into three main phases of development: seedling, vegetative, and reproductive Seedling development consists of four growth stages: unimbibed seed (S0), radicle and coleoptile emergence from the seed (S1,S2), and prophyll emergence from the coleoptile (S3) Vegetative development consists of stages V1, V2 VN; N being equal to the final number of leaves with collars on the main stem Reproductive development consists of 10 growth stages based on discrete morphological criteria: panicle initiation (R0), panicle differentiation (R1), flag leaf collar formation (R2), panicle exertion (R3), anthesis (R4), grain length and width expansion (R5), grain depth expansion (R6), grain dry down (R7), single grain maturity (R8), and complete panicle maturity (R9) Assigning rice growth stages based on discrete morphological criteria will result in unambiguous growth-stage determination For example, using this system, two people staging the same plant will arrive at the same growth stage This is because the system exploits the presence or absence of distinct morphological criteria in a symbolic logic dichotomous framework that only permits yes or no answers

725 citations

Journal ArticleDOI
26 Aug 2004-Nature
TL;DR: It is proposed that ABPH1 controls phyllotactic patterning by negatively regulating the cytokinin-induced expansion of the shoot meristem, thereby limiting the space available for primordium initiation at the apex.
Abstract: Phyllotaxy describes the geometric pattern of leaves and flowers, and has intrigued botanists and mathematicians for centuries. How these patterns are initiated is poorly understood, and this is partly due to the paucity of mutants. Signalling by the plant hormone auxin appears to determine the site of leaf initiation; however, this observation does not explain how distinct patterns of phyllotaxy are initiated. abphyl1 (abph1) mutants of maize initiate leaves in a decussate pattern (that is, paired at 180 degrees), in contrast to the alternating or distichous phyllotaxy observed in wild-type maize and other grasses. Here we show that ABPH1 is homologous to two-component response regulators and is induced by the plant hormone cytokinin. ABPH1 is expressed in the embryonic shoot apical meristem, and its spatial expression pattern changes rapidly with cytokinin treatment. We propose that ABPH1 controls phyllotactic patterning by negatively regulating the cytokinin-induced expansion of the shoot meristem, thereby limiting the space available for primordium initiation at the apex.

282 citations

Journal ArticleDOI
TL;DR: A new model and a biomimetic pattern for heliostat field layout optimization are introduced, inspired by the spirals of the phyllotaxis disc pattern, which generates layouts of both higher insolation-weighted efficiency and higher ground coverage than radially staggered designs.

257 citations