A gene conferring actidione resistance and abnormal morphology onPhysarum polycephalumplasmodia

Abstract

SUMMARYPlasmodia ofP. polycephalumhomozygous and heterozygous for a mutation (act) which confers resistance to actidione on the haploid amoebal stage have been tested for resistance to actidione in liquid semidefined medium. Growth of homozygous resistant (act/act) plasmodia determined by protein or pigment assay was inhibited less by actidione than growth of homozygous-sensitive or heterozygous plasmodia. The mutant (act) is therefore recessive but, contrary to a previous report, confers resistance on homozygous plasmodia. The same mutation affects the morphology of homozygous (act/act) plasmodia on agar medium, causing slow growth, fragmentation and excessive sliminess.