The role of Class II KNOX family in controlling compound leaf patterning in Medicago truncatula.

Compound leaf development requires the coordination of genetic factors, hormones, and other signals. In this study, we explored the functions of Class Ⅱ KNOTTED-like homeobox (KNOXⅡ) genes in the model leguminous plant Medicago truncatula. Phenotypic and genetic analyses suggest that MtKNOX4, 5 are able to repress the leaflet formation, while MtKNOX3, 9, 10 are not involved in this developmental process. Further investigations show that MtKNOX4 represses the CK signal transduction, which is downstream of MtKNOXI-mediated CK biosynthesis. Additionally, two boundary genes, FUSED COMPOUND LEAF1 (ortholog of Arabidopsis class M KNOX) and NO APICAL MERISTEM (ortholog of Arabidopsis CUP-SHAPED COTYLEDON), are necessary for the MtKNOX4-mediated compound leaf formation. These findings suggest that among the members of MtKNOXII, MtKNOX4 plays a crucial role in integrating the CK pathway and boundary regulators, providing new insights into the roles of MtKNOXⅡ in regulating the elaboration of compound leaves in M. truncatula. This article is protected by copyright. All rights reserved.