title: The circadian clock-associated small GTPase LIGHT INSENSITIVE PERIOD1 suppresses light-controlled endoreplication and affects tolerance to salt stress in Arabidopsis.
abstract: Circadian clocks are biochemical timers regulating many physiological and molecular processes according to the day/night cycle. The small GTPase LIGHT INSENSITIVE PERIOD1 (LIP1) is a circadian clock-associated protein that regulates light input to the clock. In the absence of LIP1, the effect of light on free-running period length is much reduced. Here, we show that in addition to suppressing red and blue light-mediated photomorphogenesis, LIP1 is also required for light-controlled inhibition of endoreplication and tolerance to salt stress in Arabidopsis (Arabidopsis thaliana). We demonstrate that in the processes of endoreplication and photomorphogenesis, LIP1 acts downstream of the red and blue light photoreceptors phytochrome B and cryptochromes. Manipulation of the subcellular distribution of LIP1 revealed that the circadian function of LIP1 requires nuclear localization of the protein. Our data collectively suggest that LIP1 influences several signaling cascades and that its role in the entrainment of the circadian clock is independent from the other pleiotropic effects. Since these functions of LIP1 are important for the early stages of development or under conditions normally experienced by germinating seedlings, we suggest that LIP1 is a regulator of seedling establishment.
authors.affiliation: Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary.
authors.forename: Kata
authors.initials: K
authors.lastname: Terecskei
authors.forename: Réka
authors.initials: R
authors.lastname: Tóth
authors.forename: Péter
authors.initials: P
authors.lastname: Gyula
authors.forename: Eva
authors.initials: E
authors.lastname: Kevei
authors.forename: János
authors.initials: J
authors.lastname: Bindics
authors.forename: George
authors.initials: G
authors.lastname: Coupland
authors.forename: Ferenc
authors.initials: F
authors.lastname: Nagy
authors.forename: László
authors.initials: L
authors.lastname: Kozma-Bognár
mesh_terms: D021581:Active Transport, Cell Nucleus; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000201:enzymology / Q000235:genetics; D048430:Cell Shape; D057906:Circadian Clocks; D018548:Cotyledon / Q000378:metabolism / Q000528:radiation effects / Q000648:ultrastructure; D056931:Cryptochromes / Q000235:genetics / Q000378:metabolism; D062951:Endoreduplication; D005816:Genetic Complementation Test; D058685:Genetic Pleiotropy; D018525:Germination; D008855:Microscopy, Electron, Scanning; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D055519:Photoreceptors, Plant / Q000235:genetics / Q000378:metabolism; D051939:Phytochrome B / Q000235:genetics / Q000378:metabolism; D011003:Ploidies; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D055051:Salt-Tolerant Plants / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological
chemical_list: D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; C497952:PHYB protein, Arabidopsis; D055519:Photoreceptors, Plant; D011993:Recombinant Fusion Proteins; D051939:Phytochrome B; D012965:Sodium Chloride; C525435:LIP1 small GTPase, Arabidopsis; D020559:Monomeric GTP-Binding Proteins