Molecular mechanisms underlying the determination of axillary bud fate and outgrowth into branch crown in strawberry.

AXB fate depends on position on the axis, as well as genetic and environmental factors. Here, in Fragaria vesca, we addressed the largely unanswered question of how genetic factors determine AXB fate. - To get insights into the mechanisms occuring in undifferentiated AXB with different subsequent developmental trajectories, we combined (1) phenotypic characterization of AXB fate throughout plant development with (2) molecular characterization using RNA-seq analysis of morphologically undifferentiated AXB, in three different genotypes producing either branch crowns or stolons (fvetfl1 and fvega20ox mutants, FveFT3 overexpressor). - Results shed light on the molecular mechanisms involved in the determination of AXB fate and outgrowth.

Among the genes was FveBRC1. Analysis of FveBRC1 expression in genotypes combining various traits (perpetual/seasonal flowering; runnering/runneless) and the generation of CRISPR/Cas9 brc1 mutants allowed us to show a new function of FveBRC1 in strawberry in addition to the well-known function in AXB outgrowth into branch crown. These original results introduce new hypotheses regarding the control of AXB fate determination and, consequently, the control of fruit yield in strawberry.