Promoter activity of MIR319a from Arabidopsis thaliana. Top, diagram of GUS reporter constructs. Bottom, GUS activity in transgenic A. thaliana plants. Staining of the root tip is found in both NW8 and NW9 transgenic plants, but activity in the hypocotyl and the inflorescence is only detectable in NW8 plants. Left, in NW8 plants, GUS activity is prominent in the hypocotyl of a seedling, briefly after emergence from the seed; GUS activity disappears shortly thereafter (data not shown). Right, in NW8 plants, activity in flowers is detected particularly in developing stamens and later in pollen.