ISOLATION OF TEMPERATURE-SENSITIVE MUTANTS OF ARABIDOPSIS-THALIANA THAT ARE DEFECTIVE IN THE REDIFFERENTIATION OF SHOOTS

Three temperature-sensitive mutants of Arabidopsis thaliana that were defective in the redifferentiation of shoots were isolated as tools for the study of organogenesis. M(3) lines were constructed by harvesting M(3) seeds separately from each M(2) plant Comparative examination of shoot redifferentiation in root explants of 2700 M, lines at 22 degrees C (permissive temperature) and at 27 degrees C (restrictive temperature) led to the identification of seven temperature-sensitive mutant lines. Genetic tests of three of the seven mutant lines indicated that temperature-sensitive redifferentiation of shoots in these three lines resulted from single, nuclear, recessive mutations in three different genes, designated SRD1, SRD2, and SRD3. The morphology of root explants of srd mutants cultured at the restrictive temperature suggests that the products of these SRD genes function at different stages of the redifferentiation of shoots.