Plant perception (physiology)

Plant Biology Euro sees itself as a new interdisciplinary research area that perceive their environment in connection with the question of how plants and react to it, which examines signal processing plant. This information is both electrical, as well as on the molecular level. It is assumed that the involved anatomical structures and physiological processes similar to those of animals in many ways. The terms used as well as a number of conclusions that draw the representatives of plant biology and the Euro to the postulation of "plans synapses " ( vegetable synapses ) and a "plant intelligence" ( vegetable intelligence) range, are controversial. From a majority of plant physiologists they are criticized or rejected.

Initiators and target

In order to respond to changes in environmental conditions, whether variations in light, water or nutrient supply or even threats by pests, the most multicellular plant body sensors and systems required for information acquisition and coordinated signal transduction from cell to cell. Since some scientists correlation between animals and plants have so far been insufficiently taken into account in this respect, they introduced - also with reference to several decades past studies on the electrophysiological signal processing in plants - early 21st century, the term "plant Euro biology " ( "plant neurobiology " ) into the scientific discourse.

Among the initiators of this research direction and at the same time the first proponents of the term include work groups or departments at the Universities of Bonn (Institute of Cellular and Molecular Botany, working group cytoskeleton - membrane Interactions ) and Florence ( International Laboratory of Plant Neurobiology ). The first International Symposium on Plant Biology Euro 2005 in Florence followed in the next few years more ( 2011 is the sixth in Japan). Also in 2005, the " Society for Plant Neurobiology " was founded ( in 2009 renamed " Society of Plant Signaling and Behavior" ), 2006 called this company as a specialized organ, the journal " Plant Signaling & Behavior " to life.

The plants euro biology sees itself as an interdisciplinary research approach, converge in the results from fields such as electrophysiology, cell biology, molecular biology and ecology. It deals with the question of how plants perceive their environment and respond holistically to it. The aim is thus regulate metabolism and growth of plants, a better understanding of how linking and processing of information.

Basics

The plants euro biology often refers to the end of the 19th century established "root -brain 'hypothesis of Charles and Francis Darwin, which act root tips of plants such as brains of lower animals, therefore her attention to the plant root tips, which, among other mechanisms have the gravity perception. Stressing of analogies between animal and plant the plants EUR Biology believes that equipped with sense organs and ability to root fancy food intake, the front end of the plant, the shoot, however the rear. Plants infected with a certain extent, therefore, the "head" in the ground.

The finding that electrical signals are limited in the form of action potentials not only in animal cells, but also can occur in plants, also goes back to the 19th century. As first described in 1873, the English physiologist John Scott Burdon - Sanderson electrical signals in plants. Initially it was assumed that this was limited to plants with known rapid response to mechanical stimuli, such as the mimosa ( Mimosa pudica ), the Venus Flytrap ( Dionaea muscipula ) or tendrils of climbing plants. In the 1930s, however, action potentials could be measured in giant internodal cells of Chara spp. More recently, electrical activities were at the cellular level even in several other plant species, such as cucurbits, using the patch -clamp technique, an electrophysiological measuring method demonstrated.

Breakfast also began the search for plant structures which should assume the role of animal nervous in plants. She focused on the plant vascular bundles, and experimental evidence suggested that this can spread along electrical signals over long distances. The Austrian botanist Gottlieb Haberlandt (1854-1945) and others saw in the phloem analogies to nerves. Other structures that span multiple cells across, later found approximately in plant roots or between the stalked glandular hairs and sessile, digestive secretions producing glands in species of insectivorous genus fat (Pinguicula ). Yet there was in plant physiology further argued before that plants will generally have no nerves and signals over longer distances are mainly forwarded chemically. Encouraged by this theory was the discovery of plant hormones. Also, plant cells have been viewed as fundamentally unsuitable due to their physico - structural properties such as turgor or thick cell walls for transferring electrical impulses.

Controversy publications such as the 1973 published book " The Secret Life of Plants " by Peter Tompkins and Christopher Bird, which also dealt with paranormal phenomena and plant emotions attributed, resulted from the perspective of the plants EUR biology that the elucidation of plant sensory performance in science with a " stigma of was esoteric " and thereby provided additional obstacles.

Central themes

Particularly central themes and research areas of plant biology form the euro - yet often misunderstood - complex processes of plant intercellular signal processing, which, however, takes place not only on an electrical basis, but also at the molecular level.

Electrical signaling

Since the findings of Burdon - Sanderson electrical signals were detected in numerous plant species (see above). Thus coupled ion channels in cell membranes and transport systems are also known. One of her key research tasks provides the plants EUR biology in the transfer of these results to the understanding of the electrical stimulus transmission over long distances.

Plants operate apparently two forms of electrical signal transmission. Both are characterized by transient depolarization of the membrane potential and have a refractory period (the period in which the excited cell can not react to a stimulus again ): The catcher leaves of the Venus flytrap ( Dionaea ), or water trap ( Aldrovanda ) as well as some lower plants produce omnidirectional ( in all directions ongoing ) action potentials; but more common are directional ( in one direction current ) action potentials along the vascular tissue of higher plants. In addition, as a second type of so-called " slow wave potentials". During action potentials follow an all-or -nothing principle, slow wave potential can have variable size. Follow hydraulic pressure fluctuations along the xylem of the plant axis. Vegetable action potentials are coupled to calcium, chloride and potassium channels in the cell membranes, whereas others seem mechanisms slow wave potential to be involved. When looking for the anatomical structures that perform the function of animal nerves in plants, especially sieve tubes, companion cells, the forisomes described in the pea family ( protein complexes in the phloem ) and connecting channels between cells ( plasmodesmata ), to look closer. As previously observed electrical processes with the varied responses of plants related to their environment, is still largely unknown.

Transmitter -like substances

In the plant organism molecules were found that apparently similar roles take over as neuroreceptors and neurotransmitters in animal nervous system. Thus, the known neurotransmitters in animals ( groups) Acetylcholine, catecholamines, histamine, serotonin, dopamine, melatonin, GABA and glutamate were also detected in all plants. So far it is largely unknown whether these substances only in metabolism or in the vegetable processing of stimuli play a role. At least for glutamate seems this is probably due to the discovery of corresponding receptors. For GABA, and acetylcholine, there is also evidence that they function as a transmitter in plants. Representatives of the plants described in plant biology EUR root tissue also intercellular gaps, which they called " synapses plans " characteristics of animal neuronal synapses award. Because plant roots are highly sensitive to the neurotoxic aluminum, which also in Alzheimer 's disease, a role is attributed to, they could also contribute to a better understanding of this disease because of their neuronal properties.

Importance of auxin

The plants euro biology sees the already longer known phytohormone auxin, takes over the wide range of tasks in plant growth and differentiation, also a neurotransmitter -like substance. For auxin are effective cell - to-cell transport mechanisms available to both the intracellular space ( symplast ) as well as cell walls and spaces ( apoplast ) include. Apparently, a transport is actively avoided by the cytoplasmic channels of plasmodesmata, which favors the polar transport through the apoplast. However, this transcellular transport is still poorly understood, are suspected vesicle- based processes ( endosomes ) and the involvement of specific auxin transport molecules. Overall, speaks from the perspective of plant biology euros for the similarity between auxin and neurotransmitters animal nerve cells and the observation that extracellular appliqued auxin induces rapid electrical responses of cells within a few seconds. Obviously in this case acting, other mechanisms than the long-term response under the phytohormonalen auxin effects on the transcription ( an important intermediate step in the "translation " of genes into proteins).

Connections to behavior and Ecology

In zoology, the concept of neurobiology is closely linked to the behavior research, but also to the behavior of whole animal communities. Similarly, look for the plants EUR biology of the signals that will not only coordinate and control the individual plant, but whole plant communities, companies, such as in terms of influencing the microbial communities of their root zone ( rhizosphere ). So the plants EUR biology considered plants as territorial, comparable with animals "behavioral organisms " (ie equipped with behavioral organisms), possess the skills for receiving, storing, sharing, processing and use of information from the biotic ( living ) and abiotic ( non-living ) environment. This has been misunderstood because of towards animals by orders of magnitude slower time or reaction processes from the perspective of plant biology € long. The question of how plants acquire all this information and integrate it into their response, considerable investigation focuses the plants EUR biology apply. These include ecological issues, such as according to the interactions and detection mechanisms, as they take place between plants of the same and of different kind.

Plant intelligence

The plants euro biology notes that plants possess at least many of the components that are also found in animal nervous systems and engages in this consequence also the question of a "plant intelligence" ( vegetable intelligence) on. It refers also to the Indian scientist Jagadish Chandra Bose (1858-1937), who concluded from the observation of electrical signals between plant cells in response to environmental influences that this would have a nervous system, a form of intelligence, as well as memory and learning ability. Accordingly, the plants EUR biology efforts to correspondingly broad definitions that enable it to award also plant intelligence. So intelligence is defined by detailed sensory perception, information processing, learning, memory, optimized development of (food ) resources, self-recognition, perspective and the ability to solve problems, recurring and new situation. All of these properties to träfen on plants.

Scientific controversy

2007, turned 36 scientists from 33 different institutions with a in the journal " Trends in Plant Science" published letter to the scientific community ( with David G. Robinson, director of the Heidelberg Institute for Plant Science, as Corresponding author). Under the title Plant neurobiology: no brain, no gain? ( a pun on the English word " no pain, no gain" = " no pain no gain ") was initially always criticized the term "plant biology € " that contributes little to better understand plant physiological processes. Furthermore, a number of basic assumptions of this research have been called into question. Your supporters is held to higher functional levels ( such as tissues or organs ), particularly the unauthorized transfer of similarities between animal and plant cells at the molecular level ( such as the presence of action potentials or neurotransmitter- like substances ). Due to frequent in plants cellular connections ( plasmodesmata ) correspond to transport and neurotransmitter functioning of similar substances, not to the conditions in animal cells, moreover, were not required as a result of that inevitably tight electrical coupling of plant cells transmitter substances. Moreover, the hitherto known Auxintransportmoleküle for the transport of this phytohormone be considered sufficient for - has hardly finished - additional vesicular transport mechanisms there was no need. Actually would find vesicular transport from cell to cell in plants instead, this should not be equated processes in animal nerves and synapses. Amidst allegations of superficial analogy is stressed it existed no evidence that plants would actually possess neurons, synapses, or even a brain. The width of the represented institutions in the letter ( from Italy, Germany, Switzerland, Canada, USA, France, Great Britain and the Netherlands ) makes it clear that the concept of plant biology EUR rejected the majority of experts.

In response to this criticism, the scientific opposite side emphasized, among other things, it was stated that the terminology used by their metaphors. This had proved in previous cases as useful and would generally steer the research interest in novel questions. It was next to Darwin's ' root -brain ' hypothesis (ie the assumption that behaved root tips, as if they had a brain ) on the Nobel laureate Barbara McClintock and directed the metaphor of a "genetic intelligence". Ultimately it were less about concepts as phenomena that had been overlooked by the Botany far.

2009 was published in the prestigious journal "Proceedings of the National Academy of Sciences ", a report drawn up under other by members of the International Laboratory of Plant Neurobiology at the University of Florence article. Thus, maize roots temporally synchronized, spontaneous electrical oscillations were measured in the tips. This observation is the authors' view, a clear sign that the plant root tip acts as a sensor field for various sensory perceptions from the environment. The plant electrophysiologist Dietrich degree Mann ( University of Göttingen emeritus ) threw the authors then methodically experimental shortcomings and misinterpretations of artifacts, and the editors of the magazine deficiencies in the review process before; the article should be retracted.

The controversy related to the plants EUR biology and terminology associated with it were also taken up in working with philosophical and pragmatic focus. So the philosopher Günther Witzany see the discussions about the term "plant biology € " and the question of whether intelligence can be attributed to plants, from the perspective of bio-communication as necessary to. Others consider the terminology of plant biology euros with their " zoomorphic charging " critical since it blurs the basic diversity of plants as autotrophic beings to the heterotrophic animals. This raises the question of the meaning to make a plant " the animal " in order to give it a special identity.

Theses and results of the representatives of the plant biology euro also found in popular science media echo, which here also there was a by no means uncritical.