Arabidopsis thaliana (image) Salk Institute Caption Upon sensing the threat of shade from a neighboring plant, Arabidopsis thaliana plants rapidly elongate different tissues by increasing the levels of growth-promoting hormones. This growth is regulated by the VAS1 enzyme. As seen in the photo on the right, plants lacking VAS1 have an exaggerated response to shade. Credit Courtesy of the 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. 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.