The research of my group focuses on traits with economic value (e.g. growth, wood formation, wood calorimetric content, frost hardiness and pest resistance) and also on traits with clear adaptive value (e. g. shade avoidance, timing of budset). These traits are complex, so called quantitative traits, this means that they are controlled by a large number of genes and gene interactions.
(1) Association Mapping: Wood properties and phenology
The main contribution of single nucleotide polymorphisms (SNPs) to conventional tree breeding is the possibility of early selection to shorten the breeding cycle.
Quantitative Trait Loci (QTL) analyses in conifers are typically based on association between quantitative traits and SNPs variation in single full-sib families.Presently we are performing QTL analysis for wood properties (micro fibril angle - MFA -, density, modulus of elasticity - MOE -, ring width...), growth and timing of budset in Scots pine. In Norway spruce, we are currently developing SNP data to identify a major QTL for the pendula phenotype in three full sib crosses between wild and pendula phenotypes.
Association Mapping (AM) is another genetic strategy to unravel the genetics behind complex traits. Typically, this is a gene space based method, which tests for association between candidate genes and phenotypic variation at a population level. We are currently analyzing data for wood formation, growth and phenology based on 500 half-sib families in Norway spruce as part of the spruce genome sequencing project (Wallenberg spruce project), Umeå plant science center, UPSC, SLU-UMU. Genome Wide Selection (GWS) to detect genomic regions harboring sequence variants that affect complex traits requires the development SNP data across the entire genome. Currently, we are developing a dense SNP array in Scots pine for its application in an advance Scots pine breeding pedigree as part of a PhD work, second research school in tree breeding, SLU.
(2) Physiology of light response in gymnosperms
Scots pine southwards transfers lead to increased growth, but not sufficiently to overcome the competitive advantage of the local southern trees. In other words, increased temperature is not to be the only factor promoting growth potential of the northern populations.There are many evidences supporting day length as another major environmental cue shaping the strong adaptive cline in Scots pine. Less attention has been devoted to the study of light composition (wavelength).We are studyingthe effect of light quality on three-month old Scots pine and Norway spruce seedlings. We are currently analyzing the data on hypocotyl morphology, chlorophyll and anthocyanin content, chloroplast development and qPCR on Scots pine as part of a Master thesis work.
|Bud formation in one-year-old Scots pine seedlings under greenhouse conditions.||Scots pine trees|
(3) Fine and Large genetic structure in Scots pine
Differences in genetic structure between tree species are due mainly to population history, life form and breeding system. The availability of highly variable molecular markers has facil- itated large- and fine-scale genetic structure analysis. Study of large-scale structure is relevant to correct for spatial structure in association studies and to identify new cultivars with desir- able traits (e.g., growth, flowering time...), while fine-scale is related to inbreeding and the consequent inbreeding depression. Currently, we are writing two manuscripts on the large-scale structure that resulted after post-glacial expansion in Scots pine and on the effect of forest management on the fine-scale structure in Scots pine.
4) Comparative evolutionary analysis in Gymnosperm
The majority of gymnosperms posses a large genome size com- pared to other plant groups. In order to understand genome size evolution we are performing in situ fluorescence hybridization (FISH) to investigate genome size evolution comparing Norway spruce and Gnetum (Gnetum, Welwitschia and Ephedra) genomes. In conifers, gene family evolution is also poorly understood. Based on our work on phytochrome gene family found that conifer gene families can be very complex and contribute to the enormous size of the conifer genome. In the light of our recent finding, we are investigating the composition and function of another important gene family (LP3) involved in water deficit stress. In addition, we are currently writing a manuscript on the comparative composition of EST-SSR and UTRs across multiple forestry tree species.
- Ranade SS & García-Gil MR (2013). Adaptive cline to light spectra in Scots pine (Pinus sylvestris L). Tree physiology. 4: 479-493
- Ranade SS, Abrahamsson S, Niemi J, and García-Gil MR (2013). Comparison of global expression profile under red light and far- red light in a conifer species. American Journal of Plant Science 4:479-493
- Abrahamsson S, Hallander J, Waldmann P and García-Gil MR (2013). Heterozygosity-fitness correlation (HFC) in an inbreed Scots pine population. Genetica, DOI10.1007/s10709-013-9704-y
- Nystedt B et al (2013). The draft sequence of the 20 GBp Norway spruce (Picea abies) genome (shed light on conifer genome evolution). Nature doi:10.1038/nature12211
- Sillanpää MJ, Pikkuhookana P, Abrahamsson S, Fries A and García-Gil MR (2012). Simultaneous estimation of multiple quantitative trait loci and growth curve parameters through hierarchical Bayesian modeling. Heredity 108(2): 134-146
- Abrahamsson S, Nilsson JE, Wu H, García-Gil MR, Andersson B (2012). Inheritance of height growth and autumn cold hardiness based on two generations of full-sib and half-sib families of Pinus sylvestris. Scandinavian Journal of Forest Research. 27:415-413