Investigating the Multiple Roles of Boundary Genes in Abscission in Arabidopsis thaliana

Plants shed organs through abscission. This process scatters seeds and removes foliage but can reduce crop yield if unmanaged. In the model plant species, Arabidopsis thaliana, the outer parts of the flower are shed after pollination. BLADE-ON-PETIOLE boundary genes initiate abscission zones (AZ) where separation occurs. This work focused the abscission role of boundary TALE homeodomain transcription factor genes KNOTTED1-LIKE FROM ARABIDOPSIS THALIANA2 (KNAT2), KNOTTED1-LIKE FROM ARABIDOPSIS THALIANA6 (KNAT6), and functional partner ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1). I show that TALE boundary genes are required for the correct formation of two distinct layers that develop after specification of the AZ. Collective loss of TALE activity disrupts the proper formation of both layers. I also show that TALE boundary genes are active in the signalling pathway that activates abscission, and promote the production of hydrolytic enzymes. I propose that TALE boundary genes contribute to multiple steps of the abscission process.