Elizabeth Dun

Plants, unlike animals, are amazingly plastic, having the ability to drastically change their above and below ground architecture in response to changing conditions. These changes in conditions, which may only be local to a specific plant part, can be communicated throughout the plant via long distance signals, including plant hormones, to elicit a plant-wide coordinated response. My research is concerned with the regulation of the above ground shoot architecture, or branching, and how different signals interact to control when, where and how a tiny bud will grow into a branch. This is an important plant trait, being a major determinant of yield in field, horticulture and forestry crops.

The interplay of multiple factors (including hormonal, developmental and environmental) coordinately act to regulate bud outgrowth. The plant hormones strigolactone and auxin inhibit bud outgrowth, while cytokinin promotes outgrowth. Environmental and developmental factors (i.e. photoperiod/daylength, position of axillary bud along stem) and many flowering genes also influence bud outgrowth, particularly the patterns of outgrowth. For example, photoperiod substantially affects the position of branches along the stem, even in decapitated and strigolactone-deficient plants, and therefore does not require the branching hormone strigolactone. Photoperiod regulation of branching patterns is not solely attributable to the process of flowering, as some mutants that do not flower under any photoperiod still display photoperiod-responsive vegetative traits.

My research, using the model plant garden pea (Pisum sativum), seeks to discover how strigolactones and other known hormones/signals regulate shoot architecture in response to environmental factors (photoperiod) and in coordination with developmental processes (flowering). I am studying the interactions between pathways controlling photoperiod, light response, flowering and branching which will help me to identify factors that determine position of branches along the stem. Understanding such crosstalk is important and will be an important step towards targeted modification of plant architecture, enabling bud outgrowth to be directed to desired regions or stages of plant growth.