GENETIC AND MOLECULAR CHARACTERIZATION OF EMBRYONIC MUTANTS IDENTIFIED FOLLOWING SEED TRANSFORMATION IN ARABIDOPSIS

Over 5000 trans,oenic families of Al Arabidopsis thaliana produced fol lowing seed transformation with Agrobacterium tumefaciens were screene d for embryonic lethals, defectives, and pattern mutants. One hundred and seventy-eight mutants with a wide range of developmental abnormali ties were identified. Forty-one mutants appear from genetic studies to be tagged (36% of the 115 mutants examined in detail). Mapping with v isible markers demonstrated that mutant genes were randomly distribute d throughout the genome. Seven mutant families appeared to contain chr omosomal translocations because the mutant genes exhibited linkage to visible markers on two different chromosomes. Chromosomal rearrangemen ts may therefore be widespread following seed transformation. DNA, gel blot hybridizations with 34 tagged mutants and three T-DNA probes rev ealed a wide range of insertion patterns. Models of T-DNA structure at each mutant locus were constructed to facilitate gene isolation. The value of such models was demonstrated by using plasmid rescue to clone flanking plant DNA from four tagged mutants. Further analysis of gene s isolated from these insertional mutants should help to elucidate the relationship between gene function and plant embryogenesis.