Soybean promoter activity is measured in stably-transformed hairy roots of soybean. Promoter:GFP fusions are subcloned from pFLEV into pCAMBIA1300, which is introduced into Agrobacterium rhizogenes K599. K599 is inoculated on soybean cotyledons and hairy roots are recovered after 3 weeks. Hairy roots are subcultured on a medium containing hygromycin for an additional 1-2 weeks and GFP images are collected for image analysis.