Confocal projection showing polar localisation of the auxin efflux carrier PIN1 fused to GFP. At organ inception PIN1 polarities are directed away from adjacent organ sites and towards the new site.
Using A. thaliana as a model, the Heisler group seeks to understand patterning in plant development and how it is established and regulated.
Previous and current research
In addition to providing us with the air we breathe, the food we eat and much of the energy and materials we use, plants exhibit a unique beauty associated with their strikingly symmetrical patterns of development. Multicellularity also evolved independently in plants giving us an opportunity to compare and contrast the developmental strategies used in different kingdoms.
Lateral organ formation in the model plant species Arabidopsis thaliana provides an ideal system for investigating plant development since it involves the coordination of several fundamental processes, including cell polarity, gene expression and morphogenesis. Our previous work reveals that patterns of cell polarity control both morphogenesis at the cellular level as well as at the tissue level. This integration occurs through the co-alignment of microtubule arrays with the polar localisation patterns of the auxin efflux carrier PIN1. The microtubule cytoskeleton regulates growth direction at the cellular level, while PIN1 works to concentrate the hormone auxin at the tissue level to localise growth. Our data so far suggests a role for mechanical stresses in orienting these factors and we are further investigating this possibility.
More recently we have found that organogenesis correlates spatially with a boundary between the expression domains of genes normally associated with the top (dorsal) and bottom (ventral) tissues of leaves. In fact, we have found that juxtaposition of dorsal and ventral gene expression domains is necessary for leaves to initiate properly and the creation of new dorsoventral gene expression boundaries provokes the formation of new leaf tissues along the boundary. Similar juxtaposition dependent development occurs in response to the formation of dorsoventral boundaries during insect wing and vertebrate limb development suggesting a similar logic operates in these otherwise very different contexts.
Future projects and goals
Our current and future research focuses on the establishment and function of dorsoventral boundaries in plants. Our main questions include: How do dorsoventral gene expression boundaries regulate organ morphogenesis and positioning, for example cell polarity patterns? And how are dorsoventral gene expression boundaries established and regulated?