In most flowering plants, the shoot first produces leaves then flowers in their life cycle. The transition from vegetative to reproductive development is tightly controlled by several pathways that respond to both endogenous and environmental cues. These pathways lead to the activation of floral meristem identity genes such as LEAFY (LFY) and APETALA 1 (AP1), which activate a set of floral homeotic genes to specify floral organ identities in floral meristems. While much work has focused on the activation of floral homeotic genes in flowers, little is known about how these genes are silenced in leaves and how this silencing is released in floral meristems.
In their new study titled "LEAFY and APETALA1 down-regulate ZINC FINGER PROTEIN 1 and 8 to release their repression on class B and C floral homeotic genes", the Xu lab including research technician Tieqiang Hu, graduate students Liren Du and Darren Manuela, and their mentor Dr. Mingli Xu, show that two transcription factors named ZP1 and ZFP8 act redundantly to directly repress floral homeotic genes in the leaves of Arabidopsis. ZP1 and ZP8 are then down-regulated after LFY and AP1 are activated in floral meristems. Altogether, this study reveals how floral homeotic genes are repressed and derepressed before and after floral induction.