Automated analysis of hypocotyl growth dynamics during shade avoidance in Arabidopsis
Article first published online: 2 FEB 2011
© 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd
The Plant Journal
Volume 65, Issue 6, pages 991–1000, March 2011
How to Cite
Cole, B., Kay, S. A. and Chory, J. (2011), Automated analysis of hypocotyl growth dynamics during shade avoidance in Arabidopsis. The Plant Journal, 65: 991–1000. doi: 10.1111/j.1365-313X.2010.04476.x
- Issue published online: 21 MAR 2011
- Article first published online: 2 FEB 2011
- Accepted manuscript online: 28 DEC 2010 01:23AM EST
- Received 30 September 2010; revised 14 December 2010; accepted 21 December 2010; published online 2 February 2011.
- shade avoidance;
Plants that are adapted to environments where light is abundant are especially sensitive to competition for light from neighboring vegetation. As a result, these plants initiate a series of changes known as the shade avoidance syndrome, during which plants elongate their stems and petioles at the expense of leaf development. Although the developmental outcomes of exposure to prolonged shade are known, the signaling dynamics during the initial exposure of seedlings to shade is less well studied. Here, we report the development of a new software-based tool, called HyDE (Hypocotyl Determining Engine) to measure hypocotyl lengths of time-resolved image stacks of Arabidopsis wild-type and mutant seedlings. We show that Arabidopsis grows rapidly in response to the shade stimulus, with measurable growth after just 45 min shade exposure. Similar to other mustard species, this growth response occurs in multiple distinct phases, including two phases of rapid growth and one phase of slower growth. Using mutants affected in shade avoidance phenotypes, we demonstrate that most of this early growth requires new auxin biosynthesis via the indole-3-pyruvate pathway. When activity of this pathway is reduced, the first phase of elongation growth is absent, and this is correlated with reduced activity of auxin-regulated genes. Finally, we show that varying shade intensity and duration can affect the shape and magnitude of the growth response, indicating a broad range of the elongation response to shade.