Root or Shoot (image) Salk Institute Share Print E-Mail Caption During plant embryogenesis microRNAs, labeled green, play an important part in the tightly orchestrated choreography that determines what goes up and what goes down. They ensure that HD-ZIP III genes are only expressed in the shoot meristem, which gives rise to all the above-ground portions of a plant. Credit Image: Courtesy of Zachary R. Smith, Salk Institute for Biological Studies Usage Restrictions News media reproduction to illustrate this story permitted with proper attribution as provided above. For one time use only. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.