Isoflavone synthase (IFS) tissue-specific expression in Glycine max , cultivar Williams. (A) IFS transcripts (1.7 kb) detected in a RNA blot containing 10 μg of total RNA samples purified from roots, stems, shoot tips, mature leaves, flower buds, seed coats and cotyledons of soybean plants, cv. Williams 82. Seed coats and cotyledons from three different stages of seed development were used. Seed fresh weight in milligrams is shown at bottom. (B) Expression of IFS in the cotyledon of Glycine max, cv. Williams through seed development. The 25 S ribosomal RNAs from the ethidium bromide-stained gel prior to membrane transfer are shown in the dark background sub-panels to compare RNA sample loading. The Gm-c1059-264 soybean cDNA clone was used as probe.