Publikationen in Druck
Anwer, U., Davis, A., Davis, S. J. & Quint, M. Photoperiod sensing of the circadian clock is controlled by ELF3 and GI BioRxiv (2018) DOI: 10.1101/321794
ELF3 and GI are two important components of the Arabidopsis circadian
clock. They are not only essential for the oscillator function but are
also pivotal in mediating light inputs to the oscillator. Lack of either
results in a defective oscillator causing severely compromised output
pathways, such as photoperiodic flowering and hypocotyl elongation.
Although single loss of function mutants of ELF3 and GI have been
well-studied, their genetic interaction remains unclear. We generated an
elf3 gi double mutant to study their genetic relationship in
clock-controlled growth and phase transition phenotypes. We found that
ELF3 and GI repress growth during the night and the day, respectively.
We also provide evidence that ELF3, for which so far only a growth
inhibitory role has been reported, can also act as a growth promoter
under certain conditions. Finally, circadian clock assays revealed that
ELF3 and GI are essential Zeitnehmers that enable the oscillator to
synchronize the endogenous cellular mechanisms to external environmental
signals. In their absence, the circadian oscillator fails to
synchronize to the light-dark cycles even under diurnal conditions.
Consequently, clock-mediated photoperiod-responsive growth and
development is completely lost in plants lacking both genes, suggesting
that ELF3 and GI together convey photoperiod sensing to the central
oscillator. Since ELF3 and GI are conserved across flowering plants and
represent important breeding and domestication targets, our data
highlight the possibility of developing photoperiod-insensitive crops by
manipulating the combination of these two key genes.
Publikationen in Druck
Mitra, D., Kumari, P., Quegwer, J., Klemm, S., Moeller, B., Poeschl, Y., Pflug, P., Stamm, G., Abel, S. & Bürstenbinder, K. Microtubule-associated protein IQ67 DOMAIN5 regulates interdigitation of leaf pavement cells in Arabidopsis thaliana bioRxiv (2018) DOI: 10.1101/268466
Plant microtubules form a highly dynamic intracellular network with important roles for regulating cell division, cell proliferation and cell morphology. Its organization and dynamics are coordinated by various microtubule-associated proteins (MAPs) that integrate environmental and developmental stimuli to fine-tune and adjust cytoskeletal arrays. IQ67 DOMAIN (IQD) proteins recently emerged as a class of plant-specific MAPs with largely unknown functions. Here, using a reverse genetics approach, we characterize Arabidopsis IQD5 in terms of its expression domains, subcellular localization and biological functions. We show that IQD5 is expressed mostly in vegetative tissues, where it localizes to cortical microtubule arrays. Our phenotypic analysis of iqd5 loss-of-function lines reveals functions of IQD5 in pavement cell (PC) shape morphogenesis, as indicated by reduced interdigitation of neighboring cells in the leaf epidermis of iqd5 mutants. Histochemical analysis of cell wall composition further suggests reduced rates of cellulose deposition in anticlinal cell walls, which correlate with reduced asymmetric expansion. Lastly, we provide evidence for IQD5-dependent recruitment of calmodulin calcium sensors to cortical microtubule arrays. Our work thus identifies IQD5 as a novel player in PC shape regulation, and, for the first time, links calcium signaling to developmental processes that regulate multi-polar growth in PCs.