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UBC Theses and Dissertations

Investigation of the genomics of gender regulation in Populus trichocarpa Temmel, Nyssa A.


This thesis reports the findings of four projects conducted to study the genomics of gender regulation in Populus trichocarpa. Sex-linked markers previously discovered in Salix vimilanis were tested to determine if they were also sex-linked in other Salix species and P. trichocarpa. It was found that the DNA sequence of the SCAR 354 marker, and its position at the 5’ end of a gene encoding an Ssu72-like protein, was conserved with some SFP variability in species of Salix and P. trichocarpa. While this marker may be useful for phylogenetic or population studies in Salix, this marker was not sex-linked in the species investigated in this study. An investigation of genes located on the telomeric end of chromosome 19, the putative sex chromosome in P. trichocarpa, was conducted to look for gender-biased SNPs that would indicate recombination suppression in the region on a sex locus. A large variability in the number of SNPs was observed in the gene sequences studied, but no SNPs that segregated with gender were discovered so a genetic marker that could be used to sex P. trichocarpa individuals of unknown gender could not be developed. Using a microarray approach, gender-biased gene-expression was studied in leaf tissue of P. trichocarpa. While some gender-biased gene-expression was observed in vegetative tissues the differences observed were statistically insignificant due to biological variation in the samples tested, the small sample size used in this study, and changes in the genome annotation between version 1.1 and 2.0 of the poplar genome. This study could not verify the microarray results using rtPCR in a larger sample of male and female leaf tissue. MADS-box genes involved in floral development were identified as having gender-biased gene-expression using a microarray approach. Thirteen putative MADS-box genes that showed gender-biased expression in male and female inflorescences were discovered. Novel expression patterns for nine floral MADS-box genes were identified with this microarray data, and the expression patterns of three of these genes were investigated in further detail using reverse-transcription PCR.

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