Comparative genetic studies on the APRR5 and APRR7 genes belonging to the APRR1/TOC1 quintet implicated in circadian rhythm, control of flowering time, and early photomorphogenesis.
In Arabidopsis thaliana, a number of circadian-associated factors have been identified. Among those, TOC1 (TIMING OF CAB EXPRESSION 1) is believed to be a component of the central oscillator. TOC1 is a member of a small family of proteins, designated as Arabidopsis PSEUDO-RESPONSE REGULATORS (APRR1/TOC1, APRR3, APRR5, APRR7, and APRR9). Nonetheless, it is not very clear whether or not the APRR family members other than APRR1/TOC1 are also implicated in the mechanisms underlying the circadian rhythm. To address this issue further, here we characterized a set of T-DNA insertion mutants, each of which is assumed to have a severe lesion in each one of the quintet genes (i.e. APRR5 and APRR7). For each of these mutants (aprr5-11 and aprr7-11) we demonstrate that a given mutation singly, if not directly, affects the circadian-associated biological events simultaneously: (i) flowering time in the long-day photoperiod conditions, (ii) red light sensitivity of seedlings during the early photomorphogenesis, and (iii) the period of free-running rhythms of certain clock-controlled genes including CCA1 and APRR1/TOC1 in constant white light. These results suggest that, although the quintet members other than APRR1/TOC1 may not be directly integrated into the framework of the central oscillator, they are crucial for a better understanding of the molecular mechanisms underlying the Arabidopsis circadian clock.
Yamamoto
Yoko
Y
Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya, 464-8601 Japan.
Sato
Eriko
E
Shimizu
Tomo
T
Nakamich
Norihito
N
Sato
Shusei
S
Kato
Tomohiko
T
Tabata
Satoshi
S
Nagatani
Akira
A
Yamashino
Takafumi
T
Mizuno
Takeshi
T
D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics*; D002940:Circadian Rhythm; D017343:Genes, Plant; D008027:Light; D009024:Morphogenesis; D009154:Mutation; D014157:Transcription Factors
C448160:APRR5 protein, Arabidopsis; C448161:APRR7 protein, Arabidopsis; D029681:Arabidopsis Proteins; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors