To construct the double d system containing the GAM1 and AMY genes, a 2.9 kb fragment harboring the GAM1 gene was excised from YIpdAURSGd and inserted into the SmaI-XbaI sites downstream of the ADC1 promoter (ADC1p) in YIpdAGSAd lacking the GA1 gene, thereby generating YIpdSGSAd (Fig. 1).