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Cambridge CB2 1LR
The outgrowth of buds involves complex regulation of both genes and plant hormones. One of these hormones is auxin, which plays key roles in many plant developmental processes. Growing buds export auxin, feeding into the stem vasculature of the plant, which connects to every other part of the plant. In this way, auxin is able to regulate developmental processes elsewhere. One of the ways in which it does so, is by affecting the ability of other buds to activate. With more auxin being fed into the stem vasculature, it becomes increasingly more difficult for other buds to activate. This feedback mechanism ensures that the plant is able to regulate how many buds are simultaneously active, an important aspect of the plant's ability to optimise growth under different environmental conditions. My research project focuses on how local auxin levels are able to regulate distant buds. Buds have been shown to compete in their outgrowth, where sometimes the most apical bud starts to grow and in other cases the more basal one. By measuring auxin levels in different parts of stem segments bearing dormant and/or active buds, we hope to gain more insight in how auxin levels manage to regulate this competition between buds.
The export of auxin from the bud is mediated through the activity of specialised export carriers, called PIN-proteins. The abundance and localisation of one of these proteins, PIN1, plays a key role in how much auxin is transported from the bud, and in which direction. There are some data on the dynamics of PIN1 polarisation in the stems of buds as they activate. However, less is known about PINs in the bud apex, how their repositioning might contribute to the establishment of the initial stream of auxin out of the bud, and this affects bud activation. Using confocal microscopy, I aim to visualise the dynamics of the PIN1 protein during this early event to gain a better understanding of the biological process underlying it.
The ability of auxin to regulate many fundamental developmental processes is remarkable, and despite tremendous advances in the past few decades, many questions on how it manages to do so are still unanswered. My previous research at Leiden University in The Netherlands focused on two very different plant developmental processes: the regulation of vascular cambium formation (a pre-requisite for the formation of wood) and the mechanism of fruit opening in Arabidopsis. Auxin levels play an important role in both processes, which are in turn regulated through auxin's highly specialised transport mechanism. My current research at the Leyser lab thus provides a third example of auxin-mediated plant development, and fits in perfectly with my interest in the fundamental regulation of plant development.