Dissection of a Molecular Genetic Pathway that Specifies Abaxial Leaf Identity

Rutgers University New Brunswick, New Brunswick NJ

Investigators

Abstract

Normal morphogenesis requires the proper specification of dorsal-ventral (or adaxial-abaxial) polarity during leaf development. The KANADI1 (KAN1) gene is one of the key determinants of abaxial identity in leaf development and may play a critical role in patterning the Arabidopsis embryo. KAN1 encodes a putative transcription factor of the GARP domain family (a recently identified class of DNA binding proteins in the helix-turn-helix superfamily). Little is currently known about how KAN1 specifies abaxial identity at the molecular level. In order to begin to clarify the molecular mechanisms that regulate adaxial-abaxial polarity in plants, we propose to identify downstream target genes of KAN1 and upstream regulators of KAN1. Identifying genes that regulate and are regulated by KAN1 will provide an entry point into the genetic pathways that contribute to the specification of polarity in plants. In addition, upstream regulators and downstream targets of KAN1 will provide a focus for reverse genetic approaches aimed at elucidating the functions of the many Arabidopsis genes for which no known function has yet been determined. These genomic and biochemical studies will provide a framework for understanding the regulatory network that controls leaf development and will complement ongoing genetic approaches aimed at characterizing mutants with polarity defects. Asymmetry and polarity establishment are fundamental processes in all multi-cellular organisms. Identifying the molecules and mechanisms employed by plants will enrich our knowledge of cell fate specification and provide a meaningful comparison for developmental processes that are increasingly well understood in animal systems. In addition, since the bulk of photosynthesis that contributes to plant-derived commodities, such as food, fiber, wood, and fuel, depends on leaves, understanding leaf morphogenesis has the potential to provide powerful tools for modifying agricultural products.