ABSTRACT
Auxin structure-activity relationships are significantly different in Physcomitrella paten from those which characterize higher plants. This chapter describes the relative effectiveness of some auxins and structurally related substances in promoting particular developmental changes, believed to be induced normally, i.e. in the absence of exogenous auxin, in wild type P. patens gametophytes by endogenous auxin(s). Developmentally normal strains and developmentally abnormal mutants, which are partially repairable with exogenous auxins, were used in the tests. Despite the far-reaching significance of auxin activity studies and in contrast to the numerous and extensive investigations with higher plant material, there are few reports of similar studies using eukaryotic chlorophyllous cryptogams, and then only a very small number of compounds has been tested. The chapter suggests that data are presented which demonstrate that mutants which are repairable by, or resistant to, naphth-1-ylacetic acid are also repairable by, or resistant to, indol-3-ylacetic acid.
