Sugar beet cell walls in relation to crop improvement

Sugar beet (Beta vulgaris L. subsp. vulgaris) is an economically important crop for the production of dietary sucrose. Breeding efforts towards crop improvement traditionally aim to increase sugar yield as well as in field performance. However, more recently the sugar beet pulp, a by-product of sucrose extraction, has been identified as a potential resource for additional industrial applications. Therefore breeding efforts could be directed towards the improved composition of sugar beet pulp for efficient use in these industries. Plant cell wall composition is integral to both crop performance as cell walls play a role in root growth, development and sucrose accumulation. In addition, plant cell walls make up the majority of sugar beet pulp and therefore cell wall composition influences post extraction applications. A developmental study of three Beta vulgaris varieties, utilising a monoclonal antibody directed to xylan, has allowed the visualisation of the xylem vessels within the successive cambial arrangement seen in beet roots. Importantly, a novel monoclonal antibody (LM26) directed towards phloem sieve elements has been characterised as part of this project (Torode et al., 2018). This mAb has allowed the visualisation of the relative location and abundance of phloem sieve elements in situ and how this could translate to sucrose accumulation. Monoclonal antibodies directed to several different cell wall polysaccharides were used to screen field grown commercial sugar beet (Sophia) using immunoassay techniques (Enzyme-linked immunosorbent assay (ELISA) and for the first time compared against the cell wall polysaccharide screening technique Comprehensive microarray polymer profiling (CoMPP)) on the same samples to compare the best use of these techniques. These screens indicated that sugar beet cell wall composition is modified throughout development and is influenced by environmental factors. The CoMPP technique was manipulated as a high throughput method to compare the cell wall composition of a unique population of recombinant inbred lines (RILs). Cell wall characteristics were identified which can influence the physiological properties such as sugar yield to aid the phenotyping of the varied population. From this analysis candidate lines have been selected from the RILs that have the potential to be used to direct breeding efforts towards crop improvement.