Transformation of Chlamydomonas reinhardtii with silicon carbide whiskers

Nuclear transformation of intact (walled) cells of the green alga Chlamydomonas reinhardtii was achieved by agitating the cells in the presence of plasmid DNA and silicon carbide (SiC) whiskers. The protocol was used to introduce the wild-type nitrate reductase structural gene into the nitrate reductase-deficient mutant strain nit1-305. Using SiC whiskers, 10-100 transformants per 10(7) cells were routinely produced, which is comparable to transformation rates achieved by agitating the cells with glass beads. In contrast to the glass bead protocol, cell viability was very high following treatment with SiC, with greater than 80% cell survival after agitation for 10 min. Agitation with SiC whiskers appears to be an efficient method for introducing DNA into intact C. reinhardtii cells and may prove to be applicable to other algal species for which cell wall mutants or protoplasting procedures are unavailable.