The circadian clock in plants regulates many important physiological and biological processes, including leaf movement. We have used an imaging system to genetically screen Arabidopsis seedlings for altered leaf movement with the aim of identifying a circadian clock gene. A total of 285 genes were selected from publicly available microarrays that showed an expression pattern similar to those of the Arabidopsis core oscillator genes. We subsequently isolated 42 homozygous recessive mutants and analyzed their leaf movements. We also analyzed leaf movements of activation tagging mutants that showed altered flowering time. We found that agl6-1D plants, in which AGAMOUS-LIKE 6 (AGL6) was activated by the 35S enhancer, showed a shortened period of leaf movement as well as a high level of ZEITLUPE (ZTL) expression, reduced amplitude of LATE ELONGATED HYPOCOTYL (LHY) expression, and arrhythmic TIMING OF CAB EXPRES-SION1 (TOC1)/CIRCADIAN CLOCK ASSOCIATED1 (CCA1) expression. A shortened period of leaf movement was also seen in 35S-AGL6-myc plants, although 35S-amiRAGL6 plants, transgenic plants overexpressing an artificial miRNA (amiR) targeting AGL6, showed unaltered leaf movement. The amplitude of CHLOROPHYLL A/B BINDING PROTEIN 2 (CAB2) expression, a circadian output gene, was also reduced in agl6-1D plants. Taken together, these results suggest that AGL6 plays a potential role in the regulation of the circadian clock by regulating ZTL mRNA level in Arabidopsis.
Bibliographical noteFunding Information:
We are very grateful to Steve Kay (University of California, USA) for providing toc1-1 seeds and M. Ishiura (Nagoya University, Japan) for sharing the NKTRACE program. S.K. Yoo and S.M. Hong were supported by the Brain Korea 21 program. S.M. Hong was supported by Seoul Science Fellowship. This work was supported by Creative Research Initiatives (R16-2008-106-01001-0) of the Ministry of Education, Science and Technology (MEST)/Korea Science and Engineering Foundation (KOSEF) to J.H.A.
- Circadian clock
- Leaf movement
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology