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FLOWERING LOCUS T/TERMINAL FLOWER1-Like Genes Affect Growth Rhythm and Bud Set in Norway Spruce
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. Växtbiologi och skogsgenetik, Plant Biology and Forest Genetics.
Växtbiologi och skogsgenetik, Plant Biology and Forest Genetics.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
2013 (English)In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 163, no 2, 792-803 p.Article in journal (Refereed) Published
Abstract [en]

The timing of bud set, as one determinant of the annual growth rhythm, is critical for local adaptation of the conifer Norway spruce (Picea abies). Previous gene expression and population genetic studies have suggested a role for P. abies FLOWERING LOCUS T/TERMINAL FLOWER1-Like2 (PaFTL2) in the control of growth cessation and bud set in Norway spruce as well as in local adaptation resulting in clinal variation for timing of bud set. Using transgenic plants with PaFTL2 driven by an inducible promoter, we found that PaFTL2 indeed induces bud set and most probably also growth cessation. PaFTL2 shows high expression around the procambium and vascular tissue and in the crown region in buds of both seedlings and older trees. Furthermore, PaFTL2 expression is induced in vegetative shoots and all bud types in late summer, when growth cessation occurs. This supports the notion that PaFTL2 is involved in growth cessation. A close paralog to PaFTL2, PaFTL1, is strongly expressed in meristems during the summer, possibly to repress meristem activity and the formation of needle primordia during this period. The temporal and spatial expression of PaFTL1 and PaFTL2 largely complement each other, which suggests that they act in concert to control perennial growth in Norway spruce.

Place, publisher, year, edition, pages
2013. Vol. 163, no 2, 792-803 p.
Keyword [en]
bud set, Picea abies, transformants, FT/TFL1-like genes, growth cessation
National Category
Biochemistry and Molecular Biology
URN: urn:nbn:se:uu:diva-192123DOI: 10.1104/pp.113.224139ISI: 000325554100031OAI: oai:DiVA.org:uu-192123DiVA: diva2:588965
Available from: 2013-01-16 Created: 2013-01-16 Last updated: 2014-12-19Bibliographically approved
In thesis
1. Genetic Control of Annual Growth Rhythm in the Conifer Norway Spruce (Picea Abies L. Karst)
Open this publication in new window or tab >>Genetic Control of Annual Growth Rhythm in the Conifer Norway Spruce (Picea Abies L. Karst)
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Norway spruce (Picea abies L. Karst) is a conifer belonging to the group gymnosperms and is an ecologically and economically important species in several parts of Europe. It is crucial for trees like Norway spruce to adapt timing of events such as bud set and growth cessation to the local environment in order to maximize the growth period while avoiding frost damage.

This thesis aims at widening the knowledge about genetic control of annual growth rhythm in Norway spruce and particularly the control of bud set. Using spruce transformants ectopically expressing PaFT/TFL1-LIKE 2 (PaFTL2) the prior hypothesis that PaFTL2 induces bud set is confirmed. This is further supported by spatial and temporal expression patterns in seedlings and adult trees. It is further shown that gymnosperms possess at least two FLOWERING LOCUS T/TERMINAL FLOWER 1 (FT/TFL1)-like genes with TFL1-like function, suggesting the ancestor of FT and TFL1 to be more TFL1-like. PaFTL1 appears to have complementary expression patterns to that of PaFTL2 both spatially and temporally indicating they may act together to control growth in Norway spruce.

Since bud set is controlled by photoperiod and circadian clock genes are implicated in this process, putative clock homologs were studied to gain insight into the circadian clock in gymnosperms. Several clock homologs were identified and their expression showed a diurnal pattern but the expression was rapidly damped in constant conditions. Transgenic Arabidopsis expressing putative core clock genes from spruce indicate that at least three genes, PaCCA1, PaGI and PaZTL, appear to have a conserved function between angiosperms and gymnosperms. Taken together these results suggest that gymnosperms have a similar core clock structure as angiosperms even though fundamental differences might exist since the cycling of the clock genes were rapidly damped in free-running conditions.

The studies presented in this thesis support substantial conservation of pathway components controlling photoperiodic responses in angiosperms and gymnosperms and identify PaFTL2 as a component of growth rhythm control. However, important changes in these processes are also evident. The results provide a solid basis for future research on molecular mechanisms controlling an adaptive trait in an important non-model organism.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 49 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1014
bud set, circadian clock, Picea abies, growth cessation, phosphatidyl ethanolamine-binding protein (PEBP) genes
National Category
Plant Biotechnology Biochemistry and Molecular Biology
Research subject
Biology with specialization in Evolutionary Functional Genomics
urn:nbn:se:uu:diva-192180 (URN)978-91-554-8581-8 (ISBN)
Public defence
2013-03-01, Lindahlsalen, EBC, Norbyvägen 18B, Uppsala, 10:00 (English)
Available from: 2013-02-08 Created: 2013-01-16 Last updated: 2013-04-02Bibliographically approved

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