Active Suppression of Leaflet Emergence in Simple Leaf Development

Compound leaf primordia are dissected into multiple leaflets due to sustained activity of class I KNOTTED1-LIKE (KNOXI) homeodomain transcription factors. KNOXI proteins are not detected in simple leaf primordia, and their ectopic expression fails to convert them to compound form. Molecular basis of this structural rigidity in simple leaf form is not known. Here we report the conversion of simple Arabidopsis leaves to super-compound form with indeterminate margin dissection, accompanied with ectopic KNOXI expression, by simultaneous down-regulation of the leaf maturation factors class II TEOSINTE, CYCLOIDEA, PROLIFERATING CELL FACTORS (TCPII) and KNOXII.