9722191 Williams Breeding programs have typically neglected, due to its inaccessibility, modification of the root system. No direct selection is possible for the improvement of, e.g., root structure or architecture. Selection schemes are indirect. Arabidopsis is an ideal model in which to identify the genes controlling root architecture. To identify roots with abnormal rates of lateral root formation, M2 mutagenized seeds will be screened. Only those plants in which the growth rate and morphology of the primary root is not altered will be pursued. An extensive genetic analysis of the remaining mutants will be carried out, including backcrosses into the wild type, and construction of double mutant combinations. Selected loci will be cloned. In addition, conserved regions of select genes will be used for the amplification of a lateral root cDNA library. The expression pattern of the root-specific genes and the function of the encoded gene products will be ascertained. The proposed work will be conducted primarily by undergraduate students, in summer programs and in required senior research projects. A better understanding of the plasticity of lateral root formation and of genes involved in lateral root formation will result from this project.
