Mapping of the css (chloroplast splicing suppressor) gene(s) to a recombinationally suppressed region of chromosome III in Chlamydomonas reinhardtii.
In previous work, three suppressors of defective group I introns (7151, 71N1, 7120) were isolated from a mutant of Chlamydomonas reinhardtii that had a splicing-deficient chloroplast large subunit (LSU) rRNA intron. Genetic analysis indicated that the 7151 and 71N1 suppressor mutations each involved single nuclear loci, and that the 7151 mutation was dominant. Here we present genetic evidence that the 7120 suppressor also involves a single nuclear locus and that the mutation is dominant in vegetative diploids. Moreover, we have employed crosses with the S1D2 strain and molecular markers to map the 7120 and 71N1 suppressors. Based on an analysis of 800 progeny from 7120 × S1D2, the 7120 suppressor is located in a region of ~400 kb on chromosome III that is devoid of recombination. The ~400-kb region contains at least 72 genes, about one-third of which (i.e., 22) are predicted to be organelle targeted. Similar analysis of 71N1 × S1D2 using 400 progeny also pointed to the recombination-deficient region of chromosome III, raising the possibility that these mutations could affect the same gene. These efforts lay the foundation for identifying the css (chloroplast splicing suppressor) gene(s), which promotes splicing of multiple chloroplast group I introns.
Section of Molecular Cell and Developmental Biology, and the Institute for Cellular and Molecular Biology, 1 University Station A6700, University of Texas at Austin, Austin, TX 78712, USA.
Liming
L
Luo
Jaesung
J
Lee
David L
DL
Herrin
D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics*; D032461:Chromosomes, Plant / Q000235:genetics*; D061125:Genes, Chloroplast; D016153:Genes, Suppressor; D007438:Introns; D008540:Meiosis; D012326:RNA Splicing; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D013489:Suppression, Genetic
D012335:RNA, Ribosomal