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Circadian clock components regulate entry and affect exit of seasonal dormancy as well as winter hardiness in Populus trees
Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural ences, Umeå, Sweden.
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2010 (English)In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 153, no 4, 1823-1833 p.Article in journal (Refereed) Published
Abstract [en]

This study addresses the role of the circadian clock in the seasonal growth cycle of trees: growth cessation, bud set, freezing tolerance, and bud burst. Populus tremula x Populus tremuloides (Ptt) LATE ELONGATED HYPOCOTYL1 (PttLHY1), PttLHY2, and TIMING OF CAB EXPRESSION1 constitute regulatory clock components because down-regulation by RNA interference of these genes leads to altered phase and period of clock-controlled gene expression as compared to the wild type. Also, both RNA interference lines show about 1-h-shorter critical daylength for growth cessation as compared to the wild type, extending their period of growth. During winter dormancy, when the diurnal variation in clock gene expression stops altogether, down-regulation of PttLHY1 and PttLHY2 expression compromises freezing tolerance and the expression of C-REPEAT BINDING FACTOR1, suggesting a role of these genes in cold hardiness. Moreover, down-regulation of PttLHY1 and PttLHY2 causes a delay in bud burst. This evidence shows that in addition to a role in daylength-controlled processes, PttLHY plays a role in the temperature-dependent processes of dormancy in Populus such as cold hardiness and bud burst.

Place, publisher, year, edition, pages
ASPB Publications , 2010. Vol. 153, no 4, 1823-1833 p.
National Category
Forest Science
Identifiers
URN: urn:nbn:se:umu:diva-35854DOI: 10.1104/pp.110.158220ISI: 000280566000031PubMedID: 20530613OAI: oai:DiVA.org:umu-35854DiVA: diva2:349769
Available from: 2010-09-08 Created: 2010-09-08 Last updated: 2017-12-12Bibliographically approved
In thesis
1. The circadian clock in annuals and perennials: coordination of Growth with Environmental Rhythms
Open this publication in new window or tab >>The circadian clock in annuals and perennials: coordination of Growth with Environmental Rhythms
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Since the first signs of life on planet earth, organisms have had to adapt to the daily changes between light and dark, and high and low temperatures. This has led to the evolution of an endogenous time keeper, known as the circadian clock. This biological timing system helps the organism to synchronize developmental and metabolic events to the most favorable time of the day. Such a mechanism is of considerable value to plants, since they in contrast to animals cannot change location when the environment becomes unfavorable. Thus is the ability to predict coming events of central importance in a plants life. This thesis is a study of the molecular machinery behind the clockwork in the small weed plant Arabidopsis thaliana as well as its close relative perennial; the woody species Populus. We have characterized a novel component of the circadian clock, EARLY BIRD (EBI). EBI is involved in transcriptional and translational regulation, via interaction with the known post-translational clock regulator ZEITLUPE (ZTL). In Populus, we describe the role of the circadian clock and its components with respect to entry and exit of dormancy and show that gene expression of the Populus LATE ELONATED HYPOCOTYL (LHY) genes are crucial importance for freezing tolerance and thereby survival at high latitudes. Furthermore, the input to the Populus clock is mediated via the phytochrome A (phyA) photoreceptor.

Abstract [sv]

Liv på jorden har alltid behövt anpassa sig till de dagliga växlingarna mellan främst ljus och mörker. Detta har lett till evolutionen av en intern, biologisk klocka, känd som den circadianska klockan, efter latinets ”circa diem”, som betyder ”ungefär en dag”. Denna inre klocka hjälper organismer att styra biologiska processer till den tid på dygnet som är mest gynnsam för deras utveckling och överlevnad. Denna mekanism är av stort värde för växter, eftersom de inte kan söka skydd på mera lämpliga platser om de blir utsatta för olika former av stress. Det gör att förmågan att förutse kommande händelser är av yttersta vikt för växter. Denna avhandling är en studie av det molekylära nätverk som styr denna biologiska klocka i den lilla örtplantan Arabidopsis thaliana (backtrav), och den besläktade träd-arten Populus (hybrid-asp). Vi har karaktäriserat en ny komponent i den circadianska klockan i Arabidopsis, EARLY BIRD (EBI). EBI är involverad i transkriptionell och translationell reglering av klockan, via interaktion med den kända post-translationella klock-regulatorn ZEITLUPE (ZTL). I Populus har vi beskrivit den interna klockan och dess roll i processer som invintring, vinterdvala och återstart av tillväxt. LATE ELONATED HYPOCOTYL (LHY) generna i Populus är avgörande för förvärv av köld-tolerans och således överlevnad på högre latituder. Dessutom har vi visat att signaler till den circadianska klockan i Populus är medierade via fotoreceptorn phytochrome A (phyA).

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, Institutionen för fysiologisk botanik, 2010. 61 p.
Keyword
circadian clock, arabidopsis, populus
National Category
Biochemistry and Molecular Biology Plant Biotechnology Botany
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-35870 (URN)978-91-7459-062-3 (ISBN)
Public defence
2010-10-01, KB3B1, KBC-huset, Umeå universitet, Umeå, 10:00 (English)
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Available from: 2010-09-10 Created: 2010-09-08 Last updated: 2010-09-10Bibliographically approved

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Ibáñez, CristianKozarewa, IwankaJohansson, MikaelEriksson, Maria E
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