Fig. 1. Growth assay of wild-type and mutant strains. (A) Wild-type and wal1 mutant were grown on YPD plates at the indicated temperatures for 5 days before photography. Optimal growth conditions are at 30°C. Loss of WAL1 results in slow growth and temperature sensitivity (no growth) at elevated temperatures. (B) This temperature-sensitive phenotype can be complemented by introduction of a plasmid bearing the complete WAL1 gene (pWAL1cc) at 37°C. Complementation with plasmid-borne WAL1 at lower temperatures (30°C) results in increased growth of the mutant. However, owing to lack of selective pressure to maintain the plasmid growth rate is slower than in the wild type.