Low temperatures are required to induce the development of fertile flowers in transgenic male and female early flowering poplar (Populus tremula L.).

Until now, artificial early flowering poplar systems have mostly led to the development of sterile flowers. In this study, several strategies aimed at inducting fertile flowers in pHSP::AtFT transgenic poplar were evaluated, in particular the influence of temperature and photoperiod. Our results provide evidence that temperature, and not photoperiod, is the key factor required for the development of fertile flowers in early flowering poplar.

Level of tissue differentiation influences the activation of a heat-inducible flower-specific system for genetic containment in poplar (Populus tremula L.).

Differentiation level but not transgene copy number influenced activation of a gene containment system in poplar. Heat treatments promoted CRE gene body methylation. The flower-specific transgene deletion was confirmed.

Successful crossings with early flowering transgenic poplar: interspecific crossings, but not transgenesis, promoted aberrant phenotypes in offspring.

In forest tree species, the reproductive phase is reached only after many years or even decades of juvenile growth. Different early flowering systems based on the genetic transfer of heat-shock promoter driven flowering-time genes have been proposed for poplar; however, no fertile flowers were reported until now. Here, we studied flower and pollen development in both HSP::AtFT and wild-type male poplar in detail and developed an optimized heat treatment protocol to obtain fertile HSP::AtFT flowers.

Influence of over-expression of the Flowering Promoting Factor 1 gene (FPF1) from Arabidopsis on wood formation in hybrid poplar (Populus tremula L. × P. tremuloides Michx.).

Constitutive expression of the FPF1 gene in hybrid aspen (Populus tremula L. × P. tremuloides Michx.