Loci affecting flagellar assembly and function map to an unusual linkage group in Chlamydomonas reinhardtii

The uni1 mutant of Chlamydomonas reinhardtii lacks one of the paired flagella seen in wild-type cells. The missing flagellum is cis to the eye spot and at this site the basal body is incomplete, lacking a transition zone. Together with nine other loci affecting flagellar assembly and two loci affecting flagellar function uni1 defines an approximately equal to 100-centimorgan linkage group with a circular map. Measurements of gene-centromere distances on the uni linkage group are consistent with the ordering of loci determined by recombination analysis and place the centromere near pf29, a motility-defective mutant. In well-synchronized meiotic cycles, recombination frequencies between loci on the uni linkage group but not loci on other linkage groups show striking temperature sensitivity during a 1- to 2-hr period 5 days before meiosis.