GENETIC AND MOLECULAR ANALYSIS OF LEAF DEVELOPMENT

This chapter discusses the genetic and the molecular analysis of leaf development. The pattern of successive leaves on a meristem, called phyllotaxis, has provided experimental systems for the studies of whole-plant pattern formation. Within the leaf itself, bilateral symmetry, precise and orderly vascular differentiation, and stomata1 patterns within the leaf epidermis all exemplify patterned differentiation. Various hypotheses have been put forward to explain the complex process of pattern generation in plants. The two most prominent hypotheses state: that the genetic mechanisms operate at supracellular levels to generate form and that the patterns are progressively determined in a “differentiation-dependent” manner. Plants often express a heteroblastic variation in leaf shape and size on the axis. It is, therefore, important in developmental studies to have designations for specific leaves. Leaf shape can be studied, by combining the morphological analysis with genetic clonal analysis, utilizing the somatically marked cells and the cellular site of gene action can be elucidated, by combining the clonal analysis with mutational analysis in studies of interactions between mutant and wild-type cells. © 1993, Academic Press Inc.