<p>MYBURG, ALEXANDER ANDREW. Genetic Architecture of Hybrid Fitness andWood Quality Traits in a Wide Interspecific Cross of Tree Species. (Under thesupervision of Ross W. Whetten and Ronald R. Sederoff.)The genetic architecture of interspecific differentiation plays a key role in the evolution ofreproductive isolating barriers in plants, and has important implications for hybrid breedingprograms. Interspecific hybridization is an important approach towards the genetic improvementof tree plantations. However, incompatibilities between diverged eucalypt genomesoften lead to reduced fitness of interspecific hybrids and decrease the efficiency of hybridbreeding programs. Furthermore, very little information is available on the genetic control ofquantitative traits in interspecific hybrids of tree species.The aim of this project was to obtain a detailed description of the genetic architecture ofhybrid fitness and wood property traits in an interspecific cross between two commerciallyimportant hardwood tree species, . This cross combinesthe superior growth and adaptability of E.globulus</I>. The two species are members of different sections of the subgenus Symphyomyrtus andhybrid generations of this wide cross are characterized by large amounts of F hybrid inviabilityand F hybrid breakdown.Two interspecific backcross families of were each genotyped withmore than 800 amplified fragment length polymorphism (AFLP) markers using a new high-throughputprotocol for AFLP analysis on automated DNA sequencers. A pseudo-backcrossmapping approach was used to generate detailed comparative genetic maps of a single superior Fhybrid tree and of two backcross parents. The genetic maps of the two pure species parents andthe F hybrid were colinear and 11 comparative synteny groups were characterized. Overallrecombination rates did not differ significantly, although heterogeneity in recombination rateswas observed in several map regions.Approximately 30% of the AFLP markers were significantly distorted from expectedsegregation ratios. The distorted markers were located in specific map regions and distortion washighly directional in these regions. A Bayesian Markov chain Monte Carlo approach was used toestimate the position and effect of genetic factors that cause segregation distortion. At least sixsegregation distorting loci (SDL) were located in the genetic maps of the F hybrid. Two SDLwere detected in the genome of the E.globulus</I> backcross parent. Donor alleles were found to be favored in the recurrent geneticbackground at several SDL in the maps of the F hybrid. Marker-assisted breeding based ondetailed, whole-genome genotypes of hybrids may be useful to minimize the effect of hybridbreakdown factors in further generations of this cross.Near-infrared (NIR) analysis was used to predict wood property trait values for approximately270 individuals of each backcross family after two years of growth in a field site. The trait dataand AFLP genotypes were used for QTL detection and analysis in the parental genetic maps. Inaddition, a principal component analysis was performed on the NIR spectral data of eachbackcross family and the data used to map QTLs for NIR spectral variation. A total of 18 QTLsfor NIR predicted wood properties and NIR spectral variation were characterized in the parentalmaps of the BC family.Many of the QTLs had effects on multiple, correlated wood property traits and on raw NIRspectral variation. Individual principal components of NIR spectral variation were correlated withgroups of chemical and physical wood properties, and shared several large-effect QTLs with theindividual wood properties. These QTL may represent key genetic loci that are involved in thegenetic differentiation of wood properties between these two species.<P>
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-20010723-175234 |
| Date | 24 July 2001 |
| Creators | Myburg, Alexander Andrew |
| Contributors | Ronald R. Sederoff, Ross W. Whetten, Trudy F.C. Mackay, Michael D. Purugganan |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-20010723-175234 |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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