Tetrad Analysis in Yeast
Tetrad analysis is one genetic crossing technique that was first developed for single-celled organisms, such as yeast, in which the four haploid meiotic products, or spores, are dissected.
Modifications of the technique
Manual dissection of tetrads is time-consuming, and researchers have devised high-throughput alternatives, such as barcode-enabled sequencing of tetrads. In this method, the diploid progeny of a yeast cross are transformed with a library of plasmids, each of which contains a short, unique sequence known as a “barcode” that acts as an identifier for each progeny. The plasmids also express GFP, allowing yeast asci to be selected via flow cytometry and sorted onto agar plates. The asci are lysed en masse on the plates, and the spores are allowed to grow into small colonies. The colonies can then be randomly distributed to 96-well plates for genotyping. The unique sequence barcode allows researchers to group the four colonies that arose from spores from each tetrad.