Ryan Kaye

The Mechanisms of Gravity-Dependent Non-Vertical Growth in Higher Plants

The shape of a plant and the area it occupies both above and below ground have a major impact on its ability to gather the resources it needs for growth, and, in the case of crops, to produce a high yield. Plants are sessile organisms and in order to respond to a stimulus must modify their growth, gravity is the only stimulus constantly acting upon the plant and therefore how the plant responds to gravity is a major determinant on it’s eventual shape.

Non-vertical, lateral growth is an important adaptation that allows the plant to maximise the area it can use for resource capture. How the plant’s response to gravity impacts the control of this non-vertical growth is only beginning to be understood. Many of the non-vertical growth angles within plants are maintained at angles with respect to the direction of the gravity vector, these angles are known as gravitropic setpoint angles (GSAs) and they make up a large part of the plants final shape.

The focus of this project has been to investigate the existence and maintenance of these GSAs in crop plants and further current knowledge of GSAs in the model plant Arabidopsis thaliana. This has involved screening populations produced using chemical mutagenesis and investigating the properties of mutants found through these screens. It has also involved a number of physical (e.g. clinorotation) and chemical (e.g. treatment with plant hormones such as auxin) treatments to explore GSA maintenance in a number of different species and mutants.