9317755 Green In the normal development of flowers and vegetative shoots of plants, there is a highly coordinated pattern of gene expression and morphological change. Dr. Green will study both processes and their mode of interaction. Expression gradients are postulated to set up physical expansion gradients which lead to the spontaneous complex folding of tissue. This is a new proposal for the origin of periodicity and pattern. The morphological change is postulated to act back on expression via stretch receptors or cytoskeletal responses. This completes a generative cycle for morphogenesis. Organ pattern on the sunflower head emerges in strict developmental sequence behind a circular generative zone which moves from the rim into a central field of undifferentiated cells. The major aim is to determine the relative sequence of expression events and of folding events in this meristem. Pattern and tissue folding are to be followed in detail by a non-destructive SEM replica method. Expression is to be studied by in situ hybridization. Similar analysis is proposed for other systems, including morphological mutants. Dr. Green will study changes brought on by non-invasive physical perturbation. The nature of the cyclic interaction of expression and morphological response should become clear. ***
