seasonal flowering in strawberry while FveFT 3 modulates axillary meristem fate and yield

The FveFT2 florigen/ FveTFL1 antiflorigen balance is critical for the control of seasonal flowering in strawberry while FveFT3 modulates axillary meristem fate and yield Plant architecture is central in determining crop yield. In the short-day species strawberry, a crop vegetatively propagated via daughter-plants produced by stolons, fruit yield is further dependent on the trade-off between sexual reproduction (fruits) and asexual reproduction (daughter-plants). Both are largely dependent on meristem identity, which establishes the development of branches, stolons, and inflorescences. Floral initiation and plant architecture are modulated by the balance between two related proteins, FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1). We explored in woodland strawberry the role of the uncharacterized FveFT2 and FveFT3 genes and of the floral repressor FveTFL1 through gene expression analyses, grafting and genetic transformation (overexpression and gene editing). We demonstrate the unusual properties of these genes. FveFT2 is a non-photoperiodic florigen permitting SD flowering and FveTFL1 is the long-hypothesized long-day systemic antiflorigen that contributes, together with FveFT2 , to the photoperiodic regulation of flowering. We additionally show that FveFT3 is not a florigen but promotes plant branching when overexpressed, likely through changing axillary meristem fate, thus resulting in a 3.5 fold increase in fruit yield at the expense of stolons. We show that our findings can be translated into improvement of cultivated strawberry where FveFT2 overexpression significantly accelerates flowering. by modulate and in We the leaf-expressed FveFT2 acts as a long-distance floral signal and is the long-sought after non-photoperiodic florigen permitting SD flowering. The closely related FveFT3 , which is not expressed in the leaves, modulates branching, flower number and fruit yield, likely through the modification of AXM fate. We also demonstrated that the floral repressor Fve TFL1 is indeed a mobile signal, a finding that supports old hypotheses about the existence of an antiflorigen in strawberry. Altogether, our results provide a conceptual frame for the control of floral initiation by the Fve FT2/ Fve TFL1 balance in strawberry. We further demonstrated that our findings on F. vesca can be translated to cultivated strawberry where the FveFT2 advanced and the SAM (Koskela et al ., 2012). We additionally detected its expression in the leaf. FveTFL1 is therefore a possible candidate for being the strawberry antiflorigen providing that it ( i) represses flowering, ( ii) shows long-distance mobility and ( iii) is expressed in the leaf in non-inducible LD. First, FveTFL1 represses flowering in both diploid and octoploid strawberries (Koskela et al ., 2012, 2016). Second, our results revealed that FveTFL1 overexpression in tobacco scion represses indicator shoot development, indicating a graft-transmissible floral inhibitor effect. Third, FveTFL1 is expressed in the leaf under LD. To date, photoperiodic regulation has been much less frequently observed in the TFL1 clade than in the FT clade (Wickland & Hanzawa, 2015). Actually, FveTFL1 was the first photoperiodic TFL1 gene reported (Koskela et al ., 2012), before the discovery of the chrysanthemum CsAFT (Higuchi et al ., 2013), which is an antiflorigen like FveTFL1 .