Figure 11.

A Model of How ARF3 Integrates the Repression of Cytokinin Biosynthesis by Auxin and AG to Regulate FM Determinacy.

(A) At stage 3-4 of floral development, AG indirectly represses ARF3 expression through GIK (Ng et al., 2009) and other factors and consequently enhances IPT and cell cycle gene expression to promote cell division and to maintain the meristem cell population, thereby favoring FM maintenance.

(B) At stage 5-6 of floral development, auxin and AG promote ARF3 expression, which in turn directly represses IPT3, IPT5, IPT7, and AHK4 and indirectly represses LOG gene expression. The resulting inhibition of cytokinin activity is required for the proper temporal termination of WUS expression during FM determinacy.