ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Various parameters of the Tanada effect (Proc. Natl. Acad. Sci. U.S. 59: 376–380. 1968) have been defined. This phenomenon, in which root tips of Phaseolus aureus L. adhere to a negatively charged glass surface when they are irradiated with 660 nm (red) light and release under 730 nm (far-red) light, has been characterized as follows.Secondary roots, whether etiolated or light grown exhibit photoreversible adhesion. Primary roots do not. Tips from 6–8 mm secondary roots exhibit the best response to red light, whereas tips from 3 mm roots respond best to far-red light. Red light saturetes the adhesion system at about 50 μ W/cm2xnm and far-red light, release system at about 150 ü W/cm2 xnm. The adhesion effect begins to show escape from far-red reversibility within 60–90 seconds, an observation quite different from other “typical” long term de- etiolation effects. In addition, root tips irradiated with red light begin to release spontaneously in the dark after 10 min, and have nearly completed release after 50 min. Tips irradiated with continuous red light show gradual release after 15 minutes of exposure. Whether these data indicate an extremely rapid dark reversion of Pfr to Pr or decay of Pfr under continuous red light is not known at this time.In order to study tip adhesion and release, the glass beaker surface may be negatively charged with thiocyanate (SCN-), nitrate (NO3-), sulfate (SO42-), chloride (Cl-), phosphate (PO43-), citrate (C6H5O73-), oxalate (C2O42-) or glutamine (C5H8NO4-). Benzoate (C7H5O2-) and acetate (CH3COO-) were found to be relatively ineffective for red light adhesion, however when citrate and oxalate were used release was inhibited. This was apparently due to a chelation of Ca2+since release began immediately as excess Ca+2 was added to the bathing solution.Substitution of GTP, ITP, UTP, or CTP for ATP resulted in only 20 to 40% adhesion and release for GTP, ITP and UTP, CTP showed normal adhesion kinetics under red light but very slow release kinetics under far-red light.The effects of red and far-red light in the numbers of secondary roots are that red light inhibits root initiation while far-red light partially reverses the red light effect.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1970.tb06499.x
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