Tanada effect
Encyclopedia
The Tanada effect refers to the adhesion
of root
tips to glass
surfaces. It is believed to involve electric potentials. It is named for the scientist
who first described the effect, Takuma Tanada, PhD, in 1968.
The phenomenon was observed while Dr. Tanada was rinsing glassware and noticed that excised root tips occasionally stuck to pyrex beakers. Upon investigating the phenomenon closely he determined that this process could be studied in a mixture of ATP
, ascorbate, auxin
, magnesium
, manganese
and potassium
. The tips would stick when the beaker was swirled slowly.
Most importantly, the reaction was light dependent. Exposure to red light would cause the tips to stick, while exposure to far-red would allow them to release. This simple experiment was indicative of phytochrome function, and the rapid nature of the response suggested that changes in bioelectric potential were seminal events in phytochrome
signal propagation.
Root tips stick to glass surfaces because they acquire a positive electrostatic charge due to some unknown effect from exposure to red light. The glass surface has a negative charge due to adsorbed phosphate
ions. The opposite charges attract each other.
This phenomenon is the first reported generation of a bioelectric potential by a photomorphogenic pigment.
Several years later, Dr. Tanada* found that the electric charge is generated by the trace element boron
, (Boron has been used in solar cells to generate electricity). Root tips from plants deficient in boron fail to stick to glass. In a dilute solution of boric acid
, these tips gradually stick to the glass. Boron is an element essential for the growth and development of plants and animals.
Adhesion
Adhesion is any attraction process between dissimilar molecular species that can potentially bring them in close contact. By contrast, cohesion takes place between similar molecules....
of root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
tips to glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
surfaces. It is believed to involve electric potentials. It is named for the scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
who first described the effect, Takuma Tanada, PhD, in 1968.
The phenomenon was observed while Dr. Tanada was rinsing glassware and noticed that excised root tips occasionally stuck to pyrex beakers. Upon investigating the phenomenon closely he determined that this process could be studied in a mixture of ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
, ascorbate, auxin
Auxin
Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...
, magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
, manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
and potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
. The tips would stick when the beaker was swirled slowly.
Most importantly, the reaction was light dependent. Exposure to red light would cause the tips to stick, while exposure to far-red would allow them to release. This simple experiment was indicative of phytochrome function, and the rapid nature of the response suggested that changes in bioelectric potential were seminal events in phytochrome
Phytochrome
Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is sensitive to light in the red and far-red region of the visible spectrum. Many flowering plants use it to regulate the time of flowering based on the length of day and night and to set circadian rhythms...
signal propagation.
Root tips stick to glass surfaces because they acquire a positive electrostatic charge due to some unknown effect from exposure to red light. The glass surface has a negative charge due to adsorbed phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
ions. The opposite charges attract each other.
This phenomenon is the first reported generation of a bioelectric potential by a photomorphogenic pigment.
Several years later, Dr. Tanada* found that the electric charge is generated by the trace element boron
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
, (Boron has been used in solar cells to generate electricity). Root tips from plants deficient in boron fail to stick to glass. In a dilute solution of boric acid
Boric acid
Boric acid, also called hydrogen borate or boracic acid or orthoboric acid or acidum boricum, is a weak acid of boron often used as an antiseptic, insecticide, flame retardant, as a neutron absorber, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a...
, these tips gradually stick to the glass. Boron is an element essential for the growth and development of plants and animals.
- Tanada, T. Boron – key element in the actions of Phytochrome and gravity? Planta 143:111 (1978)