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Genome mapping of Eucalyptus globulus


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Bundock, Peter C.(Peter Christian) 2002 , 'Genome mapping of Eucalyptus globulus', PhD thesis, University of Tasmania.

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This thesis covers the construction of genetic linkage maps of two Eucalyptus
globulus parental trees (chapter 2), the detection of quantitative trait loci (QTL)
carried out using these linkage maps (chapter 3) and a genetic analysis of rooting
ability of micropropagated cuttings from two E. globulus families (chapter 4).
Genetic linkage maps of two parent trees were constructed using 326 RAPD and
21 microsatellite markers. At a LOD score threshold of 4.9 for grouping and 3.0
for marker ordering, the male parent had 13 linkage groups consisting of 101
framework markers and the female parent had 11 linkage groups with 97
framework markers. Even though both parents originated from the same
provenance it was found that polymorphic RAPD markers were readily
detectable. Linkages between microsatellites previously reported for E. grandis/E.
urophylla were conserved in the E. globulus cross. Segregation distortion of
markers was found to be more prevalent than expected by chance.
The linkage maps were used to detect QTLs based on 155 progeny grown in field
trials. Twelve traits were included in the QTL analysis. These included: wood
density (Pilodyn penetration), extent of early flowering (bud abundance), and
growth (height at years one and two, stem diameter at years two, three, four and
six, and relative incremental growth between years one and two, two and four, and
four and six). Using interval mapping a total of eight QTL with LOD score peaks
over 2.0 were detected, corresponding to seven map intervals. QTL detected
included: two for cumulative growth; two for wood density; one for early
flowering and three for relative incremental growth. Since the 155 progeny trees
were grown at seven trial sites, an analysis of marker by site interaction was
carried out with more marker by site interactions being found than expected by
chance. Markers with significant QTL effects were examined for interaction with
site with both of the cumulative growth QTL found to have significant site
interaction. QTL stability with age was also analysed for these QTL, and both
growth QTL were found to have a detectable association with the first
measurements of height and diameter.
A study of the rooting ability of cuttings grown in tissue culture from two families
of E. globulus was undertaken with the aim of detecting QTLs for this trait. The
two families were found to have significantly different rooting abilities indicating
that genetic variation for the trait was present. Estimates of variance components
relating to genetic and environmental effects indicated that within both families
the variance due to genetic effects was small compared to the environmental
variance with clonal repeatabilities of 0.17 and 0.14 for the two families. These
estimates were used in power calculations based on t-tests of single markers under
some simple assumptions. However even under optimistic circumstances the
power for QTL detection was found to be too low to warrant the time and expense
of genotyping required for QTL analysis.

Item Type: Thesis - PhD
Authors/Creators:Bundock, Peter C.(Peter Christian)
Keywords: Eucalyptus, Eucalyptus
Copyright Holders: The Author
Copyright Information:

Copyright 2002 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2003. Includes bibliographical references

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