Desensitization and recovery of phototropic responsiveness in Arabidopsis thaliana

Journal Article · Thu Apr 01 00:00:00 EST 1993 · Plant Physiology; (United States)

OSTI ID:7369029

Janoudi, A K; Poff, K L ^[1]

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1. Michigan State Univ., East Lansing (United States)

Phototropism is induced by blue light, which also induces desensitization, a partial or total loss of phototropic responsiveness. The fluence and fluence-rate dependence of densensitization and recovery from desensitization have been measured for etiolated and red light (669-nm) preirradiated Arabidopsis thaliana seedlings. The extent of desensitization increased as the fluence of the desensitizing 450-nm light was increased from 0.3 to 60 [mu]mol m[sup [minus]2] s[sup [minus]1]. At equal fluences, blue light caused more desensitization when given at a fluence rate of 1.0 [mu]mol m[sup [minus]2] s[sup [minus]1] than at 0.3 [mu]mol m[sup [minus]2] s[sup [minus]1]. In addition, seedlings irradiated with blue light at the higher fluence rate required a longer recovery time than seedlings irradiated at the lower fluence rate. A red light preirradiation, probably mediated via phytochrome, decreased the time required for recovery from desensitization. The minimum time for detectable recovery was about 65 s, and the maximum time observed was about 10 min. It is proposed that the descending arm of the fluence-response relationship for first positive phototropism is a consequence of desensitization, and that the time threshold for second positive phototropism establishes a period during which recovery from desensitization occurs. 11 refs., 6 figs.

• OSTI ID: 7369029
• Journal Information: Plant Physiology; (United States), Vol. 101:4; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
ARABIDOPSIS
PHOTOSENSITIVITY
SEEDLINGS
VISIBLE RADIATION
BIOLOGICAL EFFECTS
PHYTOCHROMES
ELECTROMAGNETIC RADIATION
MAGNOLIOPHYTA
MAGNOLIOPSIDA
ORGANIC COMPOUNDS
PIGMENTS
PLANTS
PROTEINS
RADIATIONS
SENSITIVITY
560140* - Radiation Effects on Plants
550000 - Biomedical Sciences
Basic Studies