Issa, Reem Adnan (2010) Identification of glucosinolate profile in Brassica oleracea for quantitative trait locus mapping. PhD thesis, University of Warwick.

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Abstract

Glucosinolates are a group of secondary plant metabolites, which have been shown
to play important roles in human health and nutrition. Identification of novel genes or
regulators of expression are important for optimising the glucosinolate composition
of Brassica crops. This project aimed to develop a HPLC based methodology for
quantifying these compounds within Brassica leaf material and to use this to map
Quantitative Trait Loci for individual glucosinolates within Brassica oleracea
mapping populations. Glucosinolates were analysed using an optimized HPLC-UV
method developed in this study for complete separation of desulfated glucosinolates
with high resolution for quantification measurements. The reproducibility of the
desulfation reaction was improved for robust enzymatic reaction of sulfatase. A data
dependent MS and MS/MS methodology was developed to confidently identify seven
glucosinolates in the 89 AGDH plant lines distributed between aliphatic and indolic
glucosinolate, with different combinations from the parental plants A12DHd and
GDDH33. For the quantitative measurements of glucosinolates, an optimized level of
glucotropaeolin was used as an internal standard (IS1). In addition, we have
demonstrated the first use of a second internal standard (IS2) to significantly
improve the reproducibility of the quantitative measurements. Aliphatic
glucosinolates were predominant over indolic glucosinolates, where progoitrin has
the highest abundance.
This methodology was then used to identify Quantitative Trait Loci for individual
glucosinolates and for key points in their biosynthesis. A major gene effect was
found near the top of B. oleracea LG9 associated with aliphatic glucosinolate
synthesis. In addition other Quantitative Trait Loci were identified which
corresponded with previous work by other groups and to which individual gene
function could be attributed. A number of novel Quantitative Trait Loci were also
found which control the synthesis of glucosinolates distributed on the nine
chromosomes of C genome. A combination of the quantitative data and genetic
analysis of glucosinolate profiles was used to infer the existence of factors at distinct
loci and associated these with specific steps in the biosynthesis pathway of
glucosinolates in B. oleracea. The assignment of genes or gene regulator functions to
Quantitative Trait Loci identified in this study was consistent with known positions
of Brassica candidate genes and collinear regions of the Arabidopsis genome.
Consequently, this information can be applied to other Brassica species for breeding
vegetable crops with modified glucosinolate profiles.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QK Botany
Library of Congress Subject Headings (LCSH):	Glucosinolates, Cole crops, High performance liquid chromatography
Official Date:	April 2010
Dates:	Date Event April 2010 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Taylor, Paul C. ; Marsh, Andrew ; Barker, Guy C.
Sponsors:	Jāmiʻat al-ʻUlūm al-Taṭbīqīyah al-Ahlīyah [Applied Sciences University, Private (Amman, Jordan)]
Extent:	xx, 227 leaves : ill., charts
Language:	eng
URI:	http://wrap.warwick.ac.uk/id/eprint/3913

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