<i>AGLF</i> provides C-function in floral organ identity through transcriptional regulation of <i>AGAMOUS</i> in <i>Medicago truncatula</i>.

Abstract

Floral development is one of the model systems for investigating the mechanisms underlying organogenesis in plants. Floral organ identity is controlled by the well-known ABC model, which has been generalized to many flowering plants. Here, we report a previously uncharacterized MYB-like gene, <i>AGAMOUS-LIKE FLOWER</i> (<i>AGLF</i>), involved in flower development in the model legume <i>Medicago truncatula</i> Loss-of-function of <i>AGLF</i> results in flowers with stamens and carpel transformed into extra whorls of petals and sepals. Compared with the loss-of-function mutant of the class C gene <i>AGAMOUS</i> (<i>MtAG</i>) in <i>M. truncatula</i>, the defects in floral organ identity are similar between <i>aglf</i> and <i>mtag</i>, but the floral indeterminacy is enhanced in the <i>aglf</i> mutant. Knockout of <i>AGLF</i> in the mutants of the class A gene <i>MtAP1</i> or the class B gene <i>MtPI</i> leads to an addition of a loss-of-C-function phenotype, reflecting a conventional relationship of <i>AGLF</i> with the canonical A and B genes. Furthermore, we demonstrate that <i>AGLF</i> activates <i>MtAG</i> in transcriptional levels in control of floral organ identity. These data shed light on the conserved and diverged molecular mechanisms that control flower development and morphology among plant species.