A mutational analysis of leaf morphogenesis in Arabidopsis thaliana

As a contribution to a better understanding of the developmental processes that are specific to plants, we have begun a genetic analysis of leaf ontog eny in the model system Arabidopsis thaliana by performing a large-scale sc reening for mutants with abnormal leaves. After screening 46,159 M-2 indivi duals, arising from 5770 M-1 parental seeds exposed to EMS, we isolated 192 6 M-2 putative leaf mutants, 853 of which yielded Viable M-3 inbred progeny . Mutant phenotypes were transmitted with complete penetrance and small var iations in expressivity in 255 lines. Most of them were inherited as recess ive monogenic traits, belonging to 94 complementation groups, which suggest s that we did not reach saturation of the genome. We discuss the nature of the processes presumably perturbed in the phenotypic classes defined among our mutants.