ORIGIN AND DEVELOPMENT OF SHOOT ORGANS IN THE ARABIDOPSIS ROOT

Abstract

HOW ARE NEW ORGANS WITH DIFFERENT CELL LINEAGE AND TISSUE ORGANIZATION GENERATED WITHIN AND FUNCTIONALLY INTEGRATED WITH EXISTING ORGANS IN PLANTS? ALTHOUGH CLASSICAL TISSUE CULTURE STUDIES HAVE REVEALED THAT THE RATIO BETWEEN PHYTOHORMONES AUXIN AND CYTOKININ IN CULTURE MEDIA IS DECISIVE TO SPECIFY SHOOT OR ROOT REGENERATION, IT REMAINS UNCLEAR HOW CELLS IN AN EXISTING ORGAN GAIN COMPETENCE/STEMNESS AND SUBSEQUENTLY BECOME COMMITTED TO FOLLOW A DIFFERENT DEVELOPMENTAL PATHWAY. TO DECIPHER THE UNDERLYING MOLECULAR AND CELLULAR MECHANISMS, WE HAVE DEVELOPED A DEXAMETHASONE-INDUCIBLE REGENERATION SYSTEM IN THE ARABIDOPSIS ROOTS, WHICH DOES NOT REQUIRE THE USE OF TISSUE CULTURE FOR CONVERSION OF LATERAL ROOT PRIMORDIA INTO SHOOT MERISTEMS. THIS SYSTEM ALLOWS US TO DISSECT IN SPATIAL AND TEMPORAL RESOLUTION THE PROGRESSIVE STEPS NEEDED FOR THE SPECIFIC DEVELOPMENTAL PATHWAY.