Investigating the genetic control of boron concentrations in Brassica napus

The global population is projected to increase dramatically in the coming decades. This, in conjunction with climate change and arable land degradation, means that food production needs to be increased significantly. One potential method to meet this demand is to augment our understanding in (and ultimately optimise) plant nutrition, with an aim to improve crop yields. This research has focused on investigating the control of boron (B) concentrations in Brassica napus. Although B is an essential plant micronutrient, it is often deficient within the soil. Consequently, significant fertiliser inputs are required to maintain yields, which can have both negative economical and agronomical implications. One particularly pertinent example of this is the disorder ‘Brown Heart’, which affects Brassica napus var. napobrassica (the root vegetable swede). Brown Heart is specifically attributed to B-deficiency, however there is a lack of clear understanding around the basis of this disorder. This research designed a trial to explore if supplementing plants with B would reduce BH incidents. No significant reductions were observed, nor did B concentrations differ significantly between BH affected and clean roots; demonstrating that additional factors may be underlying this disorder. To further understand specific genetic factors controlling B concentrations within B. napus leaves and seeds, an Associative Transcriptomics (AT) approach was adopted. AT looked to assess how natural variation in both gene sequence and expression affected these two traits. Ten leaf and six seed AT candidates were further analysed using Arabidopsis thaliana T-DNA insertions lines, with disruption in B concentrations relative to wild type controls identified in seven T-DNA lines. Notably decreased seed B concentrations in Atnip2;1 (a member of a gene family which includes known B transporters) was identified. Markers identified from AT could be useful for marker-assisted selection strategies to improve fertiliser or B-use efficiency and ultimately positively impact crop yields.