Article

PIN1-Independent Leaf Initiation in Arabidopsis

Institute of Plant Sciences, University of Bern, CH-3013 Bern, Switzerland.
Plant physiology (Impact Factor: 6.84). 06/2012; 159(4):1501-10. DOI: 10.1104/pp.112.200402
Source: PubMed

ABSTRACT

Phyllotaxis, the regular arrangement of leaves and flowers around the stem, is a key feature of plant architecture. Current models propose that the spatiotemporal regulation of organ initiation is controlled by a positive feedback loop between the plant hormone auxin and its efflux carrier PIN-FORMED1 (PIN1). Consequently, pin1 mutants give rise to naked inflorescence stalks with few or no flowers, indicating that PIN1 plays a crucial role in organ initiation. However, pin1 mutants do produce leaves. In order to understand the regulatory mechanisms controlling leaf initiation in Arabidopsis (Arabidopsis thaliana) rosettes, we have characterized the vegetative pin1 phenotype in detail. We show that although the timing of leaf initiation in vegetative pin1 mutants is variable and divergence angles clearly deviate from the canonical 137° value, leaves are not positioned at random during early developmental stages. Our data further indicate that other PIN proteins are unlikely to explain the persistence of leaf initiation and positioning during pin1 vegetative development. Thus, phyllotaxis appears to be more complex than suggested by current mechanistic models.

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    • "[2] Auxin is crucial for the regulation of zygotic embryo development,[3] [4] root development,[2] [5] [6] including initiation and emergence of lateral roots [7À9] and the development of leaves and flowers.[10] [11] It is involved in the response of plants to light and gravity, [5] [12] general shoot and root architecture,[13] [14] organ patterning and vascular development [15À17] and apical dominancy regulation.[18] Auxin is vital for the regulation of cell division, initiation and radial position of plant lateral organs [19] and is likely to be an important regulator of nodulation.[20] "
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