ABSTRACT
This chapter presents a personal account of how hypotheses regarding the role of hydroxyproline (Hyp)/Hyp-proteins in leafy liverwort morphogenesis. The evidence that first prompted an investigation of a morphoregulatory role for Hyp in leafy liverworts actually came from a study on moss nutrition. F. C. Steward and collaborators already had done much to bring attention first to the existence of Pro-Hyp-containing proteins in plants and then to their possible role in growth and morphogenesis. The results of the physiological experiments and chemical analyses were interpreted to indicate that Hyp-protein is important in regulating leaf and branch development in at least five families of leafy liverworts and probably all leafy liverworts. In the absence of any reason to reject this interpretation, it served as the basis of our revised working hypothesis: certain Hyp-proteins play a pivotal role in leafy liverwort morphogenesis.
