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Organ initiation from the shoot apical meristem first gives rise to leaves during vegetative development and then flowers during reproductive development.LEAFY(LFY) is activated after floral induction and together with other factors promotes the floral program. LFY functions redundantly with APETALA1 (AP1) to activate the class B genesAPETALA3(AP3) andPISTILLATA(PI), the class C geneAGAMOUS(AG), and the class E geneSEPALLATA3, which leads to the specification of stamens and carpels, the reproductive organs of flowers. Molecular and genetic networks that control the activation ofAP3,PI,andAGin flowers have been well studied; however, much less is known about how these genes are repressed in leaves and how their repression is lifted in flowers. Here, we showed that two genes encodingArabidopsisC2H2 ZINC FINGER PROTEIN (ZFP) transcription factors, ZP1 and ZFP8, act redundantly to directly repressAP3,PI,andAGin leaves. AfterLFYandAP1are activated in floral meristems, they down-regulateZP1andZFP8directly to lift the repression onAP3,PI,andAG. Our results reveal a mechanism for how floral homeotic genes are repressed and derepressed before and after floral induction. 

Forage yield is largely dependent on leaf development, during which the number of leaves, leaflets, leaf size, and shape are determined. In this mini-review, we briefly summarize recent studies of leaf development in Medicago truncatula, a model plant for legumes, with a focus on factors that could affect biomass of leaves. These include: floral development and related genes, lateral organ boundary genes, auxin biosynthesis, transportation and signaling genes, and WOX related genes.