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Alteration of PHYA expression change circadian rhythms and timing of bud set in Populus
Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
Umeå University, Faculty of Science and Technology, Department of Physics. 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).
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2010 (English)In: Plant Molecular Biology, ISSN 0167-4412, E-ISSN 1573-5028, Vol. 73, no 1-2, 143-56 p.Article in journal (Refereed) Published
Abstract [en]

In many temperate woody species, dormancy is induced by short photoperiods. Earlier studies have shown that the photoreceptor phytochrome A (phyA) promotes growth. Specifically, Populus plants that over-express the oat PHYA gene (oatPHYAox) show daylength-independent growth and do not become dormant. However, we show that oatPHYAox plants could be induced to set bud and become cold hardy by exposure to a shorter, non-24 h diurnal cycle that significantly alters the relative position between endogenous rhythms and perceived light/dark cycles. Furthermore, we describe studies in which the expression of endogenous Populus tremula x P. tremuloides PHYTOCHROME A (PttPHYA) was reduced in Populus trees by antisense inhibition. The antisense plants showed altered photoperiodic requirements, resulting in earlier growth cessation and bud formation in response to daylength shortening, an effect that was explained by an altered innate period that leads to phase changes of clock-associated genes such as PttCO2. Moreover, gene expression studies following far-red light pulses show a phyA-mediated repression of PttLHY1 and an induction of PttFKF1 and PttFT. We conclude that the level of PttPHYA expression strongly influences seasonally regulated growth in Populus and is central to co-ordination between internal clock-regulated rhythms and external light/dark cycles through its dual effect on the pace of clock rhythms and in light signaling.

Place, publisher, year, edition, pages
2010. Vol. 73, no 1-2, 143-56 p.
Keyword [en]
growth cessation, dormancy, circadian clock, photoperiodism, phytochrome, populus
URN: urn:nbn:se:umu:diva-33187DOI: 10.1007/s11103-010-9619-2ISI: 000276440900013PubMedID: 20229130OAI: diva2:310689
Available from: 2010-04-15 Created: 2010-04-15 Last updated: 2014-11-17Bibliographically 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.
circadian clock, arabidopsis, populus
National Category
Biochemistry and Molecular Biology Plant Biotechnology Botany
Research subject
Molecular Biology
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)
Available from: 2010-09-10 Created: 2010-09-08 Last updated: 2010-09-10Bibliographically approved

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Kozarewa, IwankaIbáñez, CristianJohansson, MikaelÖgren, ErlingMozley, DavidNylander, EvaChono, MakikoMoritz, ThomasEriksson, Maria E
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Department of Plant PhysiologyDepartment of PhysicsUmeå Plant Science Centre (UPSC)
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