Phytochrome regulation of phytochrome A mRNA levels in the model short‐day‐plant Pharbitis nil

• Published in: Journal of experimental botany Vol. 51; no. 345; pp. 703 - 711
• Main Authors: Carter, C.E., Szmidt‐Jaworska, A., Hughes, M., Thomas, B., Jackson, S.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.04.2000; OXFORD UNIVERSITY PRESS
• Subjects: Amino Acid Sequence; Base Sequence; Biological and medical sciences; Biology and morphogenesis of the reproductive apparatus. Photoperiodism, vernalisation; Cell and Molecular Biology, Biochemistry and Molecular Physiology; Complementary DNA; Cotyledons; Darkness; Down regulation; far‐red light; FR far‐red light; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; high irradiance response; HIR; LDP; Light; long‐day plant; Messenger RNA; Molecular Sequence Data; Pfr far‐red light‐absorbing form of phytochrome; Pharbitis nil; Photoperiod; photoperiodism; Phytochrome - genetics; Phytochrome - metabolism; Phytochrome A; Plant physiology and development; Plants; Plants - genetics; Plants - metabolism; Polymerase chain reaction; red light; red light‐absorbing form of phytochrome; Reverse transcriptase polymerase chain reaction; RNA; RNA, Messenger - analysis; Scotophase; SDP; Seedlings; short‐day plant; Vegetative and sexual reproduction, floral biology, fructification; white light; Photoreception; Environmental factor; Photoperiod; Gene expression; Convolvulaceae; Regulation(control); Messenger RNA; Pharbitis nil; Dicotyledones; Light; Angiospermae; Phytochrome; Spermatophyta; Experimental plant
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jexbot/51.345.703

The exposure of dark‐grown Pharbitis nil seedlings to continuous R induces a rapid decrease in PHYA mRNA abundance with a half‐life of about 2 h. A 5 min R pulse also induces this decline, and the effect is partially reversible by subsequent FR irradiation, confirming that the regulation of expression is mediated via the Pfr form of a phytochrome. When de‐etiolated seedlings are returned to darkness after a W photoperiod, PHYA mRNA slowly reaccumulates from 20% to 50% of the dark level within 24 h. The rate of reaccumulation is greatly accelerated by the removal of Pfr with a FR pulse, resulting in reaccumulation to 100% within approximately 11 h. Without FR irradiation PHYA mRNA expression remains fully repressed for at least 11 h after the end of the photoperiod, suggesting that the controlling Pfr is highly stable.