Scheme: Wolfson Research Merit Awards
Organisation: University of York
Dates: Apr 2009-Dec 2010
Summary: Plants have an amazing ability to adjust their development according to the environment in which they are growing. A good example is the number of shoot branches, which can vary depending on nutrient availability, light quality and the health of existing shoots All gardeners know this, because it is the basis for pruning- removing the leading shoot promotes outgrowth of the side shoots below. It is easy to imagine that all these effects are simply caused by limited resource availability- new branches can’t grow because they don’t have enough nutrients or light. However, this is not the case, because different varieties of the same plant can grow with either a single unbranched shoot, or as a highly ramified bush despite being supplied with exactly the same nutrients, suggesting genetic regulation.
My research aims to elucidate how plants decide how many branches to make, and how they factor environmental information into the decision making process. The answer lies in a network of hormonal signals that move throughout the plant. These include at least one hormone moving from growing shoot tips downward to the root, and at least two moving in the opposite direction. The downward moving hormone can carry information about the activity of growing shoot tips and their nutrient status down the plant, while the upwardly moving hormones can carry information about the health of the roots and soil nutrient availability up the plant to the shoot. We aim to understand how these hormones work together modulate shoot branching depending on the environment. This is important because we have found that plants are quite conservative in their decision making, producing fewer branches, flowers and seeds than is possible with the nutrients available to them, and some varieties over-react to nutrient limitation, whereas others are less affected. Understanding these traits will help to inform crop breeding programmes, where yield stability with low fertilizer input is now a priority.