Genetic mosaics and the analysis of leaf development

Genetic mosaics with phenotypic markers can be used to study the development of normal leaves. Mosaics synthesized between normal cells and cells possessing developmental mutations can be used to determine whether or not a mutation acts cell autonomously or if cell-to-cell interactions occur. This article reviews the use of cytochimeras, plastid chimeras, radiation-induced chimeras, and graft chimeras to analyze leaf development in angiosperms and to gain insight into the cell lineage, cell-to-cell communication, and the control of morphology. New data are also presented. Leaves of plastid chimeras and graft chimeras were analyzed to determine the level of cell autonomy in different regions of the leaf blade. Evidence that small populations of leaf cells can act out developmental programs is presented. The relationship of these leaves to concepts such as developmental compartments, organismal theory, and pattern formation is discussed.