VARIABLE (CA GT)(N) SIMPLE SEQUENCE REPEAT DNA IN THE ALGA CHLAMYDOMONAS/

A partial genomic DNA library of Chlamydomonas reinhardtii was screene d with an (AC)(11) probe for the presence of (CA/GT)(n) simple sequenc e repeats (SSRs). Based on the frequency of these repeats in the parti al genomic library, we estimate that (CA/GT)(n) repeats occur at a rat e of about one every 17.7 kb in the C. reinhardtii genome. Ten positiv e clones were sequenced and four polymerase chain reaction (PCR) prime r sets flanking (CA/GT)(n) sequences were constructed for four loci. T he PCR was used to specifically amplify these regions from multiple is olates of C. reinhardtii. All four loci were highly polymorphic in the C. reinhardtii isolates. A simple Mendelian inheritance pattern was f ound for all four loci, which showed 2:2 segregation in the tetrads re sulting from a cross between C. reinhardtii and C. smithii. Our result s suggest that these simple sequence repeat DNA loci will be useful fo r identity testing, population studies, linkage analysis, and genome m apping in Chlamydomonas.