Indexed on: 27 Jun '20Published on: 28 Jul '19Published in: The Plant Journal
Leaves are derived from shoot apical meristem with three distinct dorsoventral, proximodistal and mediolateral axes. Different regulators are involved in the establishment of leaf polarity. Members of the class III homeodomain-leucine zipper (HD-ZIPIII) gene family are critical players in the determination of leaf adaxial identity mediated by microRNA165/166. However, their roles in compound leaf development are still unclear. By screening of a retrotransposon-tagged mutant population of the model legume plant Medicago truncatula, a mutant line with altered leaflet numbers was isolated and characterized. Mutant leaves partially lost their adaxial identity. Leaflet numbers in the mutant were increased along the proximodistal axis, showing pinnate pentafoliata leaves in most cases, in contrast to the trifoliate leaves of wild type. Detailed characterization revealed that a lesion in a HD-ZIPIII gene, REVOLUTA (MtREV1), resulted in the defects of the mutant. Overexpression of MtMIR166-insensitive MtREV1 led to adaxialized leaves and ectopic leaflets along the dorsoventral axis. Accompanying the abnormal leaf patterning, the content of free auxin was affected. Our results demonstrated that MtREV1 plays a key role in determination of leaf adaxial-abaxial polarity and compound leaf patterning, which is associated with proper auxin homeostasis. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.