Open Collections

Gozdzik, Jedrzej

University of British Columbia

The cuticles covering aerial organs of most plants contain a complex mixture of fatty acid-derived waxes, with various chain lengths and diverse functional groups. These waxes can form crystals which then dictate the physical properties of the surface, by accumulating either ubiquitous compounds or specialty components that are restricted to certain taxa. Relatively little is known about the biosynthesis of the specialty compounds, and whether unrelated species utilize the same mechanisms to form them. However, specialty wax biosynthesis must be elucidated to understand the formation of wax crystals and, therefore, the mechanisms underlying plant protection against drought and other stresses. The goal of my thesis is to further our understanding of the biosynthesis of specialty compounds ketones and β-diketones. Specifically, I aimed to: (i) carry out in-depth wax analyses of co-occurring compound classes, homologs and isomers with implications for possible biosynthetic mechanisms; (ii) identify and characterize enzymes involved in β-diketone formation based on comparative analysis of β-diketones and related compounds in closely and remotely related plant species. This work was done on species that were confirmed or suspected to comprise ketones and β-diketones. Furthermore, the species were chosen for their importance as food crops (Allium fistulosum, Triticum aestivum), ornamental plants (Dianthus species) or biofuels (Panicum virgatum). To achieve the first goal, I analyzed and compared the wax compositions of Allium fistulosum wild type and a wax-deficient mutant, which allowed for elucidation of the mechanism for ketone and ketol formation by carbon chain elongation, in contrast to the previously described hydroxylation mechanism. For the waxes of Dianthus species, I found characteristic chain length profiles that had implications for the mechanisms underlying β-diketone production. To achieve the second goal, I carried out wax analyses of several species across Poaceae subfamilies to investigate the ubiquity of their biosynthetic mechanisms. This was followed by characterization and functionalization of the main enzymes involved in β-diketone production. Overall, this work highlights the importance of understating the underlying mechanisms behind mid-chain functional compound production and the effects those mechanisms have on chain-length, deposition and therefore crystal formation.

Text

2023-12-06

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/86773

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/