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Transgenic hybrid aspen trees with increased gibberellin (GA) concentrations suggest that GA acts in parallel with FLOWERING LOCUS T2 to control shoot elongation
Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).ORCID iD: 0000-0003-2038-4892
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2015 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 205, no 3, 1288-1295 p.Article in journal (Refereed) Published
Abstract [en]

Bioactive gibberellins (GAs) have been implicated in short day (SD)-induced growth cessation in Populus, because exogenous applications of bioactive GAs to hybrid aspens (Populus tremulaxtremuloides) under SD conditions delay growth cessation. However, this effect diminishes with time, suggesting that plants may cease growth following exposure to SDs due to a reduction in sensitivity to GAs.

In order to validate and further explore the role of GAs in growth cessation, we perturbed GA biosynthesis or signalling in hybrid aspen plants by overexpressing AtGA20ox1, AtGA2ox2 and PttGID1.3 (encoding GA biosynthesis enzymes and a GA receptor).

We found trees with elevated concentrations of bioactive GA, due to overexpression of AtGA20ox1, continued to grow in SD conditions and were insensitive to the level of FLOWERING LOCUS T2 (FT2) expression. As transgenic plants overexpressing the PttGID1.3 GA receptor responded in a wild-type (WT) manner to SD conditions, this insensitivity did not result from limited receptor availability.

As high concentrations of bioactive GA during SD conditions were sufficient to sustain shoot elongation growth in hybrid aspen trees, independent of FT2 expression levels, we conclude elongation growth in trees is regulated by both GA- and long day-responsive pathways, similar to the regulation of flowering in Arabidopsis thaliana.

Place, publisher, year, edition, pages
2015. Vol. 205, no 3, 1288-1295 p.
Keyword [en]
Flowering Locus T2 (FT2), gibberellins (GA), growth cessation, photoperiod, Populus
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URN: urn:nbn:se:umu:diva-100766DOI: 10.1111/nph.13144ISI: 000348730600038PubMedID: 25382585OAI: diva2:807927
Available from: 2015-04-26 Created: 2015-03-09 Last updated: 2015-11-06Bibliographically approved

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Eriksson, Maria E.
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Department of Plant PhysiologyUmeå Plant Science Centre (UPSC)
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