Most cited article - PubMed ID 17368081
The intercellular transport of auxin is driven by PIN-formed (PIN) auxin efflux carriers. PINs are localized at the plasma membrane (PM) and on constitutively recycling endomembrane vesicles. Therefore, PINs can mediate auxin transport either by direct translocation across the PM or by pumping auxin into secretory vesicles (SVs), leading to its secretory release upon fusion with the PM. Which of these two mechanisms dominates is a matter of debate. Here, we addressed the issue with a mathematical modeling approach. We demonstrate that the efficiency of secretory transport depends on SV size, half-life of PINs on the PM, pH, exocytosis frequency and PIN density. 3D structured illumination microscopy (SIM) was used to determine PIN density on the PM. Combining this data with published values of the other parameters, we show that the transport activity of PINs in SVs would have to be at least 1000× greater than on the PM in order to produce a comparable macroscopic auxin transport. If both transport mechanisms operated simultaneously and PINs were equally active on SVs and PM, the contribution of secretion to the total auxin flux would be negligible. In conclusion, while secretory vesicle-mediated transport of auxin is an intriguing and theoretically possible model, it is unlikely to be a major mechanism of auxin transport in planta.
- Keywords
- 3D-SIM microscopy, PIN transporters, auxin, mathematical modeling, polar auxin transport, secretion,
- MeSH
- Arabidopsis metabolism MeSH
- Models, Biological * MeSH
- Biological Transport MeSH
- Endocytosis MeSH
- Indoleacetic Acids metabolism MeSH
- Cell Membrane Permeability MeSH
- Arabidopsis Proteins metabolism MeSH
- Secretory Vesicles metabolism MeSH
- Green Fluorescent Proteins metabolism MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Indoleacetic Acids MeSH
- Arabidopsis Proteins MeSH
- Green Fluorescent Proteins MeSH
Plant integrity looks like a "very easy and expanded topic," but the reality is totally different. Thanks to the very high specialization of scientists, we are losing a holistic view of plants and are making mistakes in our research due to this drawback. It is necessary to sense a plant in their whole complexity--in both roots and shoot, as well as throughout their life cycles. Only such an integrated approach can allow us to reach correct interpretations of our experimental results.
- Keywords
- desired types of plants, development, growth, plant integrity, roots, seeds,
- MeSH
- Breeding * MeSH
- Plant Roots growth & development MeSH
- Seeds growth & development MeSH
- Plant Development MeSH
- Research * MeSH
- Crops, Agricultural growth & development MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
The concept of plant intelligence, as proposed by Anthony Trewavas, has raised considerable discussion. However, plant intelligence remains loosely defined; often it is either perceived as practically synonymous to Darwinian fitness, or reduced to a mere decorative metaphor. A more strict view can be taken, emphasizing necessary prerequisites such as memory and learning, which requires clarifying the definition of memory itself. To qualify as memories, traces of past events have to be not only stored, but also actively accessed. We propose a criterion for eliminating false candidates of possible plant intelligence phenomena in this stricter sense: an "intelligent" behavior must involve a component that can be approximated by a plausible algorithmic model involving recourse to stored information about past states of the individual or its environment. Re-evaluation of previously presented examples of plant intelligence shows that only some of them pass our test.
