The red/white colony color assay in the yeast Saccharomyces cerevisiae: epistatic growth advantage of white ade8-18, ade2 cells over red ade2 cells

Abstract

In the yeast Saccharomyces cerevisiae the ade2, and/or the ade1, mutation in the adenine biosynthetic pathway leads to the accumulation of a cell-limited red pigment, while epistatic mutations in the same pathway, i.e. ade8, preclude this phenomenon, resulting in normal white colonies. The shift in color from red to white (or vice versa) with a combination of appropriate wild-type and mutant alleles of the adenine-pathway genes has been widely utilized as a non-selective phenotype to visualise and quantify the occurrence of various genetic events such as recombination, conversion and aneuploidy. It has provided an invaluable tool for the study of gene dosage and plasmid stability. In competition experiments between disrupted ade2, ade8-18 transformants carrying either a functional or non-functional episomal ADE8 gene, we verified that white ade8 ade2 cells show a remarkable selective advantage over red ade2 cells, with important implications on the use of this assay for the monitoring of genetic events. The accumulation of the red pigment in ade2 cells is likely to be the cause for impaired growth in these cells.

RAM: A Conserved Signaling Network That Regulates Ace2p Transcriptional Activity and Polarized Morphogenesis

“…Mutant ade2⌬ cells grown in medium containing low levels of adenine are red, due to the accumulation of a red biosynthetic precursor of adenine (Ugolini and Bruschi, 1996). ade2⌬ ade8⌬ double mutants fail to accumulate the red pigment due to a blockage at an earlier step in biosynthesis and therefore grow as white colonies.…”

Evaluation of the lower protein limit in the budding yeast Saccharomyces cerevisiae using TIPI-gTOW

“…ADE2 encode phosphoribosylaminoimidazole carboxylase, an enzyme involved in the adenine synthesis. Reduction of Ade2 protein can be indirectly monitored by assessing cellular growth defect and by accumulation of red pigment in the absence of adenine [25]. We integrated ADE2 with the TEV-induced degron expressed from the CDC19 promoter into the chromosomal ADE2 locus (Figure 1).…”

Generation of a Ustilago maydis ade2 Mutant

“…The remaining 143 colonies (68%) were repeatedly replica-plated and subjected to eight to ten rounds of selection on minimal media with and without adenine to select for homogeneous homokaryon auxotrophic ade2 knockout mutants (Figure 2). Initially these colonies were pale pink, as seen in ade2 mutants in yeast and Candida albicans [14,17], but this accumulation of pink colour was lost during the repeated rounds of selection. This experimental result demonstrates a simple method to produce adenine-dependent auxotrophic mutants of Ustilago using plasmid pKO_Ade2_Phleo.…”

“…Yeast ADE2 is the required purine biosynthetic gene for phosphoribosylaminoimidazole carboxylase (AIR carboxylase). Knockout ade2 strains produce pink colonies on non-selective media [14]. Ustilago ade2 knockout strains, dependent on adenine supplementation of minimal media, were created using a single plasmid, pKO_Ade2_Phleo, available upon request.…”