Plasticity and evolution in drought avoidance and escape in the annual plant Brassica rapa
Article first published online: 6 JAN 2011
© 2011 The Author. New Phytologist © 2011 New Phytologist Trust
Volume 190, Issue 1, pages 249–257, April 2011
How to Cite
Franks, S. J. (2011), Plasticity and evolution in drought avoidance and escape in the annual plant Brassica rapa. New Phytologist, 190: 249–257. doi: 10.1111/j.1469-8137.2010.03603.x
- Issue published online: 25 FEB 2011
- Article first published online: 6 JAN 2011
- Received: 12 August 2010, Accepted: 22 November 2010
- Brassica rapa;
- contemporary evolution;
- global climate change;
- natural selection;
- phenotypic plasticity;
- plant phenology;
- water use efficiency
- •A key question in ecological genetics is to what extent do plants adapt to changes in climatic conditions, such as drought, through plasticity or evolution.
- •To address this question, seeds of 140 maternal families of Brassica rapa were generated from collections made before (1997) and after (2004) a natural drought. These seeds were planted in the glasshouse and grown under low-water and high-water conditions.
- •Post-drought lines flowered earlier than pre-drought lines, showing an evolutionary shift to earlier flowering. There was significant genetic variation and genotype by environment (G × E) interactions in flowering time, indicating genetic variation in plasticity in this trait. Plants that flowered earlier had fewer leaf nodes and lower instantaneous (A/g) and integrated (δ13C) water use efficiency than late-flowering plants.
- •These results suggest that B. rapa plants escape drought through early flowering rather than avoid drought through increased water use efficiency. The mechanism of this response appears to be high transpiration and inefficient water use, leading to rapid development. These findings demonstrate a trade-off between drought avoidance and escape, and indicate that, in this system, where drought acts to shorten the growing season, selection for drought escape through earlier flowering is more important than phenotypic plasticity.