Identification of CYP79B2 and CYP79B3. (A) Yeast expressing CYP79B2 are resistant to 5FI. A saturated culture (0.1 ml) of diploid strain L5140 × L5141 carrying either CYP79B2 or the library vector was mixed with 3.7 ml of molten 0.7% agar and plated onto complete minimal medium lacking uracil and containing 2% galactose and 2 mg/liter Trp. After the top agar had solidified, sterile filter disks were placed onto the surface and 10 μl of the indicated concentration of 5FI was pipetted onto the filter. Yeast plates were incubated for 48 h and photographed. (B) Alignments of deduced amino acid sequences of the CYP79B2 and CYP79B3 proteins and the Sorghum CYP79A1 protein. Sequences were aligned with the program megalign (DNAstar, Madison, WI) by using the Clustal method (24). Amino acid residues identical in at least two of three sequences are boxed, and hyphens indicate gaps introduced to maximize alignment. GenBank accession numbers for the previously identified sequences are: CYP79B2, ATT5J17.120; CYP79B3, AC006592.4; and CYP79A1, U32624. Sequences for the newly isolated cDNAs of CYP79B2 and CYP79B3 are identical to the previously identified sequences.