Volatile apocarotenoid biosynthesis and carotenoid catabolism in Arabidopsis thaliana
| dc.contributor.author | Rivers, John Yates | |
| dc.date.accessioned | 2018-05-29T01:45:27Z | |
| dc.date.available | 2018-05-29T01:45:27Z | |
| dc.date.issued | 2017 | |
| dc.description.abstract | Carotenoids are essential for plant photosynthesis. But, the story doesn’t end there: volatile apocarotenoids, carotenoid oxidative cleavage products, are important plant fragrances and semiochemicals, and some are believed to be so-called ‘apocarotenoid signals’ (ACS), regulating plant processes. From in vitro experiments, apocarotenoids are known to be formed either by carotenoid cleavage dioxygenases (CCDs) or non-enzymatic oxidation. But, in planta mechanisms are in many cases unclear. Are there volatile apocarotenoids yet to be discovered? Are volatile apocarotenoids formed via CCD or non-enzymatic processes in planta? And are some volatile apocarotenoids ACSs? To study volatile apocarotenoid metabolism in planta, a solid phase microextraction (SPME) gas chromatography mass spectrometry (GC/MS) protocol for analysing volatile apocarotenoids was developed. I also detoured to examine a new MS ionisation technology, cold electron ionisation (cold-EI). This technology improves molecular mass determination via GC/MS. The ability of cold-EI to enhance GC/MS plant volatile identification (via provision of molecular mass data) was evaluated. SPME-GC/MS was then applied to analyse volatile apocarotenoid profiles from the model plant Arabidopsis thaliana. Col-0 (wild-type) and ccd-loss-of-function single and double mutants were analysed, as were the Arabidopsis ccr2 mutant and corresponding ccr2-background ccd mutants. ccr2 accumulates linear carotenoids not typically observed in Arabidopsis, and I’ve found it also emits exotic volatile apocarotenoids. A more-targeted study of volatile apocarotenoids and CCD1 and CCD4 activity during senescence was also performed. This thesis discusses aspects of analytical method development, specifically optimisation and applications of SPME sampling and cold-EI technology. Using untargeted SPME-GC/MS volatile metabolomics, a remarkable breadth of known and putative volatile apocarotenoids was uncovered in Arabidopsis. Evidence suggests CCDs barely contribute to volatile apocarotenoid production, most likely producing non-volatile apocarotenoids instead. Volatile apocarotenoids seem to be formed mainly via carotenoid non-enzymatic oxidation. My results suggest carotenoid turnover in photosynthetic tissues is important: volatile apocarotenoid production often increases markedly when CCD function is lost. Despite previous studies’ results, no new evidences were found for CCD-derived ACS contributing to either the ccr2 phenotype or senescence retardation. | en_AU |
| dc.identifier.other | b4966203x | |
| dc.identifier.uri | http://hdl.handle.net/1885/143632 | |
| dc.language.iso | en | en_AU |
| dc.subject | Arabidopsis thaliana | en_AU |
| dc.subject | apocarotenoids | en_AU |
| dc.subject | carotenoids | en_AU |
| dc.subject | apocarotenoid signals | en_AU |
| dc.subject | ACS | en_AU |
| dc.subject | volatiles | en_AU |
| dc.subject | carotenoid cleavage dioxygenase | en_AU |
| dc.subject | CCD | en_AU |
| dc.subject | plant metabolism | en_AU |
| dc.subject | solid-phase microextraction | en_AU |
| dc.subject | SPME | en_AU |
| dc.subject | gas-chromatography mass spectrometry | en_AU |
| dc.subject | GC/MS | en_AU |
| dc.subject | electron ionisation | en_AU |
| dc.subject | EI | en_AU |
| dc.title | Volatile apocarotenoid biosynthesis and carotenoid catabolism in Arabidopsis thaliana | en_AU |
| dc.type | Thesis (PhD) | en_AU |
| dcterms.valid | 2018 | en_AU |
| local.contributor.affiliation | Research School of Biology, The Australian National University | en_AU |
| local.contributor.authoremail | u4541684@anu.edu.au | en_AU |
| local.contributor.supervisor | Pogson, Barry | |
| local.description.notes | the author deposited 29/05/2018 | en_AU |
| local.identifier.doi | 10.25911/5d65145a6ca5b | |
| local.identifier.proquest | Yes | |
| local.mintdoi | mint | |
| local.type.degree | Doctor of Philosophy (PhD) | en_AU |