In flowering plants, the opening of the anther to release pollen is carefully timed to maximise reproductive potential. Manipulation of this process is an important tool for plant breeding and the production of hybrid crops. Dehydration of the anther epidermis, combined with the presence of secondary thickening within the endothecium layer, is required to create biomechanical changes that enable anther dehiscence. Both passive and active processes contribute to the targeted removal of water from the anther walls, however the genetic factors controlling water movement are not known. Furthermore, the presence of stomata on anthers may enhance water loss via evaporation. In plants, active movement of water can be achieved by regulation of water channels and by changes to the osmotic potential of organs; this was explored in the context of changes in the anther driving anther dehiscence and pollen release. qRT-PCR analysis was used to identify aquaporin and sucrose transporter genes that are upregulated during anther dehiscence in Arabidopsis thaliana. For genes of interest, the phenotypes of available mutants were characterised. Combinations of single, double and triple mutants showed changes in fertility and variations in floral organ lengths. Analysis of GUS reporter lines showed that the promoter activity of different aquaporins is confined to specific parts of the flower. The results suggest that certain aquaporins isoforms enhance hydraulic conductivity in different parts of the flower, which could contribute to water transport required for petal and filament extension. The importance of evaporation during anther dehydration was also investigated. The phenotypes of Arabidopsis mutant lines with varying stomatal densities were characterised, and changes in fertility were investigated under different environmental conditions. High relative humidity delayed anther dehiscence and affected pollen viability, resulting in reduced fertility. Plants that have no anther stomata were most severely affected. These results suggest that water loss via evaporation is important for anther opening in Arabidopsis, and that the presence of stomata on anthers facilitates this process.

The roots of a plant play a vital role in its growth and development, but due to practical difficulties of observing underground roots, the study of their shape has long been neglected. Recent advances in CT imaging technology have allowed for accurate non-destructive imaging of root systems in soil. This technique has formed the basis of the FutureRoots project. The main challenge with analysing the shape of a plant root system is that they have varying topological structure, so traditional shape analysis methods cannot be applied. In this thesis, we develop three approaches for analysing wheat root systems. The first approach involves measuring a set of pre-chosen root traits, and analysing this set using conventional statistical methods. This approach is effective but may miss potentially important shape information and the large number of measurable traits reduces the potential power of statistical tests. The second approach is to perform pairwise comparisons based on the Hausdorff Metric and use Multidimensional scaling to reduce a large set of pairwise comparisons to a dataset which can be analysed with conventional statistical methods. This approach can detect and test for overall shape differences but can fail to detect subtle differences. The third approach is to apply the Persistent Homology technique from Topological Data Analysis, which is designed to find underlying topological differences between two shapes. This method successfully finds differences but it is difficult to interpret the results. We will apply these three techniques to simulated data and a real life dataset. In addition, because of experimental considerations, the wheat roots had to be unnaturally constrained to a small area so we have developed a method to estimate how they would have grown unconstrained.

X-ray micro computed tomography (µCT) is increasingly applied in plant biology as an imaging system that is valuable for the study of root development in soil, since it allows the three-dimensional and non-destructive visualisation of plant root systems. Variations in the X-ray attenuation values of root material and the overlap in measured intensity values between roots and soil caused by water and organic matter represent major challenges to the extraction of root system architecture. We propose a novel technique to recover root system information from X-ray CT data, using a strategy based on a visual tracking framework embedding a modiffed level set method that is evolved using the Jensen-Shannon divergence. The model-guided search arising from the visual tracking approach makes the method less sensitive to the natural ambiguity of X-ray attenuation values in the image data and thus allows a better extraction of the root system. The method is extended by mechanisms that account for plagiatropic response in roots as well as collision between root objects originating from different plants that are grown and interact within the same soil environment. Experimental results on monocot and dicot plants, grown in different soil textural types, show the ability of successfully extracting root system information. Various global root system traits are measured from the extracted data and compared to results obtained with alternative methods.