Molecular mechanisms underlying the high oleic acid phenotype in sunflower Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/w9505385t

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Wildtype sunflower typically produces 12-24% oleic acid (18:1) and 70-82% linoleic acid (18:2). High-oleic sunflower, by contrast, produces up to 80-94% oleic acid. The monounsaturated oleic acid has a greater oxidative stability than the polyunsaturated linoleic acid, predominant in wildtype sunflower, and has greater nutritional benefits than polyunsaturated and saturated fatty acids. High oleic sunflower lines are based on high-oleic acid germplasm, which originated from an induced mutation (Oh). Oi is necessary but often not sufficient for producing the high oleic phenotype, presumably because additional quantitative trait loci (QTL) segregate in some genetic backgrounds. The seed specific oleate desaturase (FAD2-1), which displays greatly reduced transcript levels in high oleic lines, has been established as the principal candidate gene affecting oleic acid content in sunflower kernels and cosegregates with Ol. In this research, we demonstrated that the FAD2-1 gene is tandemly duplicated in mutant high oleic sunflower lines, with the two copies being separated by 3.1 kb. We showed that reduced transcript levels of FAD2-1 in developing kernels of high oleic lines were caused by the RNA interference (RNAi) pathway. Further evidence was obtained when sense and antisense transcripts of FAD2-1 were detected in mutant lines; wildtype lines only produced transcripts in the sense direction. Bi-directional transcripts formed double-stranded RNA, which serve as a trigger for RNAi machinery. In addition, we compared the transcript levels of 48 glycerolipid biosynthetic genes in the developing kernels of four low and four high oleic sunflower lines using microarrays. The analyses revealed that the lipid transfer protein was the only additional gene besides FAD2-] with differing transcript levels in each of the four low versus high oleic comparisons. The microarray experiments also revealed no significant differences in transcript levels for genes directly involved in oleic acid synthesis for three of the four comparisons. Only one comparison showed differing transcript levels for about a quarter of the genes in the glycerolipid biosynthesis. Sequence-based molecular markers were developed for eleven candidate genes involved in the oleic acid biosynthesis and used to identify candidate genes for the QTL underlying oleic acid content in sunflower seeds. A population of 262 recombinant inbred lines segregating for oleic acid content was analyzed and revealed that the oleic acid phenotype is caused by the intralocus and interlocus effects of several genes. These findings emphasize the complexity of the phenotype and indicate a limitation in the applicability of marker-assisted selection for high oleic acid content. Overall, our understanding of the molecular mechanisms underlying the high oleic acid phenotype in sunflower increased.
License
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome, 8-bit Grayscale) using ScandAll PRO 1.8.1 on a Fi-6770A in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2012-05-01T16:42:19Z (GMT). No. of bitstreams: 1SchuppertGunnarFelix2005.pdf: 39007160 bytes, checksum: 6acdca564d9b53a32e5d35fbb5e9fc9b (MD5) Previous issue date: 2004-10-21
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-04-27T17:48:59Z (GMT) No. of bitstreams: 1SchuppertGunnarFelix2005.pdf: 39007160 bytes, checksum: 6acdca564d9b53a32e5d35fbb5e9fc9b (MD5)
  • description.provenance : Submitted by Tamera Ontko (toscannerosu@gmail.com) on 2012-04-23T21:05:19ZNo. of bitstreams: 1SchuppertGunnarFelix2005.pdf: 39007160 bytes, checksum: 6acdca564d9b53a32e5d35fbb5e9fc9b (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-05-01T16:42:19Z (GMT) No. of bitstreams: 1SchuppertGunnarFelix2005.pdf: 39007160 bytes, checksum: 6acdca564d9b53a32e5d35fbb5e9fc9b (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items