Thesis
Does it Cut the Mustard? Dissecting the Genetic Basis of Seed Glucosinolate (GSL) Accumulation in Indian Mustard (Brassica Juncea L.)
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2022
DOI:
https://doi.org/10.25918/thesis.271
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Abstract
The mustard family, Brassicaceae, consists of economically important species cultivated as oilseeds, vegetables, and condiment crops. Brassicaceae produce glucosinolates (GSLs), a large class of well-studied sulphur- and nitrogen-containing secondary metabolites. GSLs and their breakdown products have been implicated in plant defence and fitness. They serve as flavour in food and some are associated with specific human health benefits. The economic value of Indian mustard (Brassica juncea L.) as an oilseed, vegetable, livestock feed, or condiment largely depends on its GSL levels. Thus, depending on end-use, either GSL reduction – for oil and feedstock industries or GSL enrichment – for vegetable, condiment and nutraceutical industries, are important breeding targets.
Despite foundational knowledge derived from Arabidopsis and other Brassica crops, GSL modulation in B. juncea has been hampered by the innate intricacy of GSL metabolism, which is further compounded by its complex amphidiploid genome. The primary aim of this thesis was to expand the knowledge of GSL metabolism in B. juncea through quantitative genetic and functional genomic approaches.
First, a set of 158 diverse accessions from 28 countries was characterised for variation of GSL content, with a focus on the dominant GSL sinigrin and gluconapin. Two major divergent genepools, reflecting different geographical origin – South Asia and outside of South Asia, displayed divergence in GSL content and composition. South Asian accessions accumulated gluconapin, while the rest of the accessions predominantly accumulated sinigrin.
Second, trait architecture of GSL was dissected through a genome-wide association study (GWAS), which discovered several significant quantitative trait loci (QTL), containing high confidence homologues of known and potential GSL metabolic network genes. The divergence of genepools in respect to GSL metabolism was reflected in the distinct and non-overlapping QTLs for sinigrin and gluconapin.
Third, a set of three contrasting lines for total GSL content and profile were used for transcriptomic analysis of developing siliques. Comparative analysis of the respective GSL metabolic networks identified strong regulatory and structural determinants for the low GSL trait, as well as for the accumulation of the health beneficial sinigrin.
Collectively genomic and transcriptomic data revealed the extent of complexity of GSL metabolic network in B. juncea and identified a set of QTL and candidate genes valuable for further functional characterisation and deployment in variety improvement targeting manipulation of GSL content.
Details
- Title
- Does it Cut the Mustard? Dissecting the Genetic Basis of Seed Glucosinolate (GSL) Accumulation in Indian Mustard (Brassica Juncea L.)
- Creators
- Erwin Tandayu
- Contributors
- Tobias Kretzschmar (Supervisor) - Southern Cross UniversityPriyakshee Borpatragohain (Supervisor) - Southern Cross University
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xvi, 179
- Identifiers
- 991013122513802368
- Copyright
- © E Tandayu 2022
- Academic Unit
- Faculty of Science and Engineering
- Resource Type
- Thesis