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

Abstract Plant migration and gene flow from genetically-modified or exotic trees to nearby lands by crossing with wild relatives is a major public regulatory concern. Many genetic strategies exist mitigate potential flow, however, the long delay in onset of flowering severe constraint research progress. We used heat-induced-FT-overexpression speed assessment expected floral phenotypes after CRISPR knockout poplar homologs key genes, LEAFY AGAMOUS. selected events previously characterized CRISPR-Cas9 induced biallelic changes then re-transformed them Arabidopsis thaliana FLOWERING LOCUS T (AtFT) under control either strong constitutive promoter heat-inducible promoter. successfully obtained both male female clones poplar, observing wide range inflorescence forms among flowers, ramets, insertion events. Overall, flowers LFY AG targeted were consistent what would be predicted for loss-of-function these genes. LFY-targeted showed small catkins leaf-like organs, AG-targeted had nested organs reduction determinacy absence well-formed carpels anthers. These findings demonstrate great developmental plasticity Populus during genetically accelerated flowering, which may horticultural value. They also provide an informative early view apparent sterility knockouts targets.