Faster Evaluation of Induced Floral Sterilit

Abstract

A major concern over the use of transgenic trees is the potential for transgene dispersal through pollen and seeds. The incorporation of sterility inducing genes into transgenic lines of trees has been proposed to reduce or even avoid gene flow of transgenes into non-transgenic interbreeding species. The evaluation of strategies for the induction of sterility in transgenic forest tree species has been hindered by their long vegetative phases. In this study an early flowering 35S::Leafy poplar line was used for the faster evaluation of the sterility construct C-GPDHC::Vst1. The combination of two transgenic approaches, one to induce early flowering and a second for the induction of sterility, allowed evaluation of this sterility strategy two years after transformation. This is a very short period of time considering the long vegetative period of seven to twenty years common in forest tree species. This approach opens opportunities for the assessment of sterility mechanisms for this plant group.

Fate of forest tree biotechnology facing climate change

“…Several approaches have been proposed to impede the escape and containment of transgenes (Brunner et al, 2007;Ahuja, 2011b;Hoenicka et al, 2012b). These include: (1) reproductive sterility and early flowering (Strauss et al, 1995;Hoenicka and Fladung, 2006b;Brunner et al, 2007;Traenkner et al, 2010;Klocko et al, 2016Klocko et al, , 2018Briones et al, 2020), (2) site-specific excision of transgene mediated by recombinase systems, where the functional transgene is removed from the gametes before flowering (Luo et al, 2007;Gidoni et al, 2008;, and (3) introducing transgenes into the chloroplasts genome to reduced transgene escape via pollen (Bock 2006;Verma and Daneill, 2007). Transgene escape from transgenic populations is a virtual reality, and none of these approaches would likely achieve 100 percent transgene containment in the forest trees in a real world (Ahuja, 2009(Ahuja, , 2011bEllstrand, 2018).…”

Variation in floral form of CRISPR knock-outs of the poplar homologs of LEAFY and AGAMOUS after FT heat-induced early flowering

“…Sometimes, in addition to the desired early flowering, there were unintended impacts on vegetative form. For example, the use of the strong viral-derived 35S promoter to control target gene expression often resulted in shortened plant stature, as was observed for poplar, plum, and eucalypts [ 10 , 21 , 28 , 32 , 41 ]. Therefore, it can be challenging to parse out any vegetative differences if this accelerated flowering system is used to assess vegetative impacts of genetic containment systems.…”