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Gene Expression Analyses and Association Studies of Wood Development Genes in Loblolly Pine (Pinus taeda L.)Palle, Sreenath Reddy 2010 August 1900 (has links)
Gene expression analyses using native populations can provide information on the genetic and molecular mechanisms that determine intraspecific variation and contribute to the understanding of plant development and adaptation in multiple ways. Using quantitative real time – polymerase chain reaction (qRT-PCR), we analyzed the expression of 111 genes with probable roles in wood development in 400 loblolly pine individuals belonging to a population covering much of the natural range. Association mapping techniques are increasingly being used in plants to dissect complex genetic traits and identify genes responsible for the quantitative variation of these traits. We used candidate-gene based association studies to associate single nucleotide polymorphisms (SNPs) in candidate genes with the variation in gene expression. The specific objectives established for this study were to study natural variation in expression of xylem development genes in loblolly pine (Pinus taeda L.) using qRT-PCR, to associate SNPs in candidate genes with the variation in gene expression using candidate-gene based association analyses and to detect loblolly pine promoter polymorphisms and study their effect on gene expression.
Out of the 111 genes analyzed using qRT-PCR, there were significant differences in expression among clones for 106 genes. Candidate-gene based association studies were performed between 3937 single nucleotide polymorphisms (SNPs) and gene expression to associate SNPs in candidate genes with the variation in gene expression. To the best of our knowledge, this is the first association genetic study where expression of a large number of genes, analyzed in a natural population, has been the phenotypic trait of interest. We cloned and sequenced promoters of 19 genes, 16 of which are transcription factors involved in wood development and drought response. SNP discovery was done in 13 of these promoters using a panel of 24 loblolly pine clones (unique genotypes). SNP genotyping is underway in the entire association population and association analyses will be done to study the effects of promoter SNPs on gene expression. The results from this project are promising and once these associations have been tested and proved, we believe that they will help in our understanding of the genetics of complex traits.
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Novel resources enabling comparative regulomics in forest tree species / Nya verktyg för komparativ regulomik i skogsträdSundell, David January 2017 (has links)
Lignocellulosic plants are the most abundant source of terrestrial biomass and are one of the potential sources of renewable energy that can replace the use of fossil fuels. For a country such as Sweden, where the forest industry accounts for 10% of the total export, there would be large economical benefits associated with increased biomass yield. The availability of research on wood development conducted in conifer tree species, which represent the majority of the forestry in Sweden, is limited and the majority of research has been conducted in model angiosperm species such as Arabidopsis thaliana. However, the large evolutionary distance between angiosperms and gymnosperms limits the possibility to identify orthologous genes and regulatory pathways by comparing sequence similarity alone. At such large evolutionary distances, the identification of gene similarity is, in most cases, not sufficient and additional information is required for functional annotation. In this thesis, two high-spatial resolution datasets profiling wood development were processed; one from the angiosperm tree Populus tremula and the other from the conifer species Picea abies. These datasets were each published together with a web resource including tools for the exploration of gene expression, co-expression and functional enrichment of gene sets. One developed resource allows interactive, comparative co-expression analysis between species to identify conserved and diverged co-expression modules. These tools make it possible to identifying conserved regulatory modules that can focus downstream research and provide biologists with a resource to identify regulatory genes for targeted trait improvement. / Lignocellulosa är den vanligast förekommande källan till markburen biomassa och är en av de förnybara energikällor som potentiellt kan ersätta användningen av fossila bränslen. För ett land som Sverige, där skogsindustrin som står för 10 \% av den totala exporten, skulle därför en ökad produktion av biomassa kunna ge stora ekonomiska fördelar. Forskningen på barrträd, som utgör majoriteten av svensk skog är begränsad och den huvudsakliga forskningen som har bedrivits på växter, har skett i modell organismer tillhörande gruppen gömfröiga växter som till exempel i Arabidopsis thaliana. Det evolutionära avståndet mellan gömfröiga (blommor och träd) och nakenfröiga (gran och tall) begränsar dock möjligheten att identifiera regulatoriska system mellan dessa grupper. Vid sådana stora evolutionära avstånd krävs det mer än att bara identifiera en gen i en modellorganism utan ytterligare information krävs som till exempel genuttrycksdata. I denna avhandling har två högupplösta experiment som profilerar vedens utveckling undersökts; ett från gömfröiga träd Populus tremula och det andra från nakenföriga träd (barrträd) Picea abies. Datat som behandlats har publicerats tillsammans med webbsidor med flera olika verktyg för att bland annat visa genuttryck, se korrelationer av genuttryck och test för anrikning av funktionella gener i en grupp. En resurs som utvecklats tillåter interaktiva jämförelser av korrelationer mellan arter för att kunna identifiera moduler (grupper av gener) som bevaras eller skilts åt mellan arter över tid. Identifieringen av sådana bevarade moduler kan hjälpa att fokusera framtida forskning samt ge biologer en möjlighet att identifiera regulatoriska gener för en riktad förbättring av egenskaper hos träd.
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