New Mutations Affecting Meristem Growth and Potential in Petunia hybridaVilm

Abstract

Genetic diversity has been induced in Petunia hybrida using the chemical mutagen ethane methyl sulphonate with the intent to investigate the genetic control of lateral branching, an important developmental process responsible for establishing plant architecture. Three genetic loci have been identified in petunia that are required for the expression of apical dominance during the vegetative phase of growth. Recessive mutations at these loci produce a highly branched growth habit, but have minimal pleiotropic effects. Two mutants have been identified that are useful for studying sympodial branching during growth of the reproductive shoot axis. The sympodial (sym) mutant dramatically alters reproductive shoot architecture by modifying the timing of sympodial meristem initiation and meristem potential. The arborescent (arb) mutant retains normal timing of sympodial branching, but the mutation prevents floral identification, showing that sympodial branching can be uncoupled from floral determination. Each mutant class provides insight into the role of meristem growth and potential in establishing plant architecture through lateral branching.