RADIATION-SENSITIVE MUTANTS OF ARABIDOPSIS-THALIANA

Five Arabidopsis mutants have been isolated on the basis of hypersensi tivity of leaf tissue to UV light. For each mutant, the UV-hypersensit ive phenotype (uvh) was inherited as a single recessive Mendelian trai t. In addition, each uvh mutant represented a separate complementation group. Three of the mutations producing the UV hypersensitive phenoty pe have been mapped relative to either genetic markers or physical mic rosatellite polymorphisms. Locus UVH1 is linked to nga76 on chromosome 5, UVH3 to GL1 on chromosome three, and UVH6 to nga59 on chromosome 1 . Each uvh mutant has a characteristic pattern of sensitivity based on UV sensitivity of leaf tissue, UV sensitivity of root tissue, and ion izing radiation sensitivity of seeds. On the basis of these patterns, possible molecular defects in these mutants are discussed.