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ARS Home » Pacific West Area » Albany, California » Plant Gene Expression Center » Research » Publications at this Location » Publication #161029
Title: ARABIDOPSIS PSEUDO-RESPONSE REGULATOR7 IS A SIGNALING INTERMEDIATE IN PHYTOCHROME-REGULATED SEEDLING DEETIOLATION AND PHASING OF THE CIRCADIAN CLOCK

Author
item KACZOROWSKI, KAREN - UCB-ARS PLNT GENE EXP CTR
item QUAIL, PETER - UCB-ARS PLNT GENE EXP CTR

Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2003
Publication Date: 11/1/2003
Citation: KACZOROWSKI, K.A., QUAIL, P.H. ARABIDOPSIS PSEUDO-RESPONSE REGULATOR7 IS A SIGNALING INTERMEDIATE IN PHYTOCHROME-REGULATED SEEDLING DEETIOLATION AND PHASING OF THE CIRCADIAN CLOCK. THE PLANT CELL. 2003. 15:2654-2665.

Interpretive Summary: To identify new components in the phytochrome (phy) signaling network in Arabidopsis, we used a sensitized genetic screen for seedlings defective in responsiveness to light. We identified a gene, called PRR7, that functions in relaying signals from the phytochrome molecule, both to light regulated genes and to the biological clock.

Technical Abstract: To identify new components in the phytochrome (phy) signaling network in Arabidopsis, we used a sensitized genetic screen for deetiolation-defective seedlings. Two allelic mutants were isolated that exhibited reduced sensitivity to both continuous red and far-red light, suggesting involvement in both phyA and phyB signaling. The molecular lesions responsible for the phenotype were shown to be mutations in the Arabidopsis PSEUDO-RESPONSE REGULATOR7 (PRR7) gene. PRR7 is a member of a small gene family in Arabidopsis previously suggested to be involved in circadian rhythms. A PRR7'-glucuronidase fusion protein localized to the nucleus, implying a possible function in the regulation of photoresponsive gene expression. Consistent with this suggestion, prr7 seedlings were partially defective in the regulation of the rapidly light-induced genes CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), observable as a premature increase in expression level during the second peak of the biphasic induction profile that is elicited upon initial exposure of dark-grown seedlings to light. A similar 3- to 6-h coordinated advance in peak free-running expression of CCA1, LHY, and TIMING-OF-CAB1, which are considered to encode the molecular components of the circadian oscillator in Arabidopsis, was observed in entrained fully green prr7 seedlings compared with wild-type seedlings. Collectively, these data suggest that PRR7 functions as a signaling intermediate in the phytochrome-regulated gene expression responsible for both seedling deetiolation and phasing of the circadian clock in response to light.