Dr Angharad Jones
Cell Growth and Division in the Shoot Apical Meristem
The shoot apical mersitem produces all of the above-ground organs of the plant. At the centre of the structure is a group of cells, the stem cells, that remain undifferentiated and grow and divide slowly. In the region surrounding stem cells, growth and division are more rapid and cells begin to receive signals to differentiate. In contrast to the uniform growth that is seen in the central zone, which maintains an evenly domed structure, the tissue of the peripheral zone grows heterogeneously and bumps that are the beginnings of new organs are formed. I am interested in whether the changes in shape we see in the tissue of the peripheral zone as organs start to develop can be explained by the decisions that individual cells make between growth and division.
An image of the shoot apical meristem of Arabidopsis produced using a confocal microscope
Using confocal microscopy to make time-lapse movies, I am studying cell growth and division during the formation of floral organs in detail. I am developing a system based on the combination of different fluorescent reporter proteins that allows the progression of the cell cycle to be monitored in living cells. Using these reporters the lengths of the different phases of the cell cycle can be measured and correlated with other behaviour such as growth.
An example of a time-course experiment showing the appearance and disappearance of a cell-cycle reporter
Regulation of Root-hair Length by Auxin Transport
Root-hair cells are a specialised cell type found in the root epidermis. They develop alongside non-hair cells, which are specialised for different functions. While working at the University of Bristol with Prof. Claire Grierson and Dr. Colin Lazarus, I mapped the location of auxin transporters in the developing root epidermis using fluorescent protein reporters and identified that hair and non-hair cells have different auxin-transport capacities. This data was used to produce a computational model of auxin flow, which we then used to predict how changes to the pattern of epidermal cell types would affect the length of root hairs produced. This work showed that in Arabidopsis thaliana, non-hair cells are required to channel auxin to developing hair cells and sustain their growth. This work was carried out in collaboration with Dr. Eric Kramer (Bard College, Simon’s Rock), Prof. Malcolm Bennett (University of Nottingham) and Prof. Ottoline Leyser (University of York).
Root-hairs are specialised structures that grow out from epidermal cells by polar growth and are important for water and nutrient uptake