Fig. 6. A model for pattern formation along the mediolateral axis of the ovary in Arabidopsis. Three domains are specified by the opposing gradients of two antagonistic factors: valve factors (FIL/JAG activity; blue) and replum factors (class I KNOX genes; yellow). The FIL/JAG activity specifies valve formation, class I KNOX genes determine the replum, and the valve margin (green) is formed in the region in which both valve factors and replum factors are expressed. The AS function (red), carried out by AS1 and AS2, represses class I KNOX genes, preventing the expression of these genes in valves and maintaining their expression below certain levels in the replum and valve margin.