The AGAMOUS-LIKE 20 MADS domain protein integrates floral inductive pathways in Arabidopsis

Abstract

The very late-flowering behavior of Arabidopsiswinter-annual ecotypes is conferred mainly by two genes,FRIGIDA (FRI) and FLOWERING LOCUS C(FLC). A MADS-domain gene, AGAMOUS-LIKE 20(AGL20), was identified as a dominant FRI suppressor in activation tagging mutagenesis. Overexpression of AGL20suppresses not only the late flowering of plants that have functionalFRI and FLC alleles but also the delayed phase transitions during the vegetative stages of plant development. Interestingly, AGL20 expression is positively regulated not only by the redundant vernalization and autonomous pathways of flowering but also by the photoperiod pathway. Our results indicate that AGL20 is an important integrator of three pathways controlling flowering in Arabidopsis.