Improved vectors for retron-mediated CRISPR-Cas9 genome editing in .

site-directed mutagenesis is a powerful genetic tool for testing the effects of specific alleles in their normal genomic context. While the budding yeast possesses classical tools for site-directed mutagenesis, more efficient recent CRISPR-based approaches use Cas 'cutting' combined with homologous recombination of a 'repair' template that introduces the desired edit. However, current approaches are limited for fully prototrophic yeast strains, and rely on relatively low efficiency cloning of short gRNAs.