| 1. |
- Berlin Kolm, Sofia, et al.
(författare)
-
Genetic diversity, population structure and phenotypic variation in European Salix viminalis L. (Salicaceae)
- 2014
-
Ingår i: Tree Genetics & Genomes. - : Springer Science and Business Media LLC. - 1614-2942 .- 1614-2950. ; 10:6, s. 1595-1610
-
Tidskriftsartikel (refereegranskat)abstract
- To investigate the potential of association genetics for willow breeding, Salix viminalis germplasm was assembled from UK and Swedish collections (comprising accessions from several European countries) and new samples collected from nature. A subset of the germplasm was planted at two sites (UK and Sweden), genotyped using 38 SSR markers and assessed for phenological and biomass traits. Population structure, genetic differentiation (F-ST) and quantitative trait differentiation (Q(ST)) were investigated. The extent and patterns of trait adaptation were assessed by comparing F-ST and Q(ST) parameters. Of the 505 genotyped diploid accessions, 27 % were not unique. Genetic diversity was high: 471 alleles was amplified; the mean number of alleles per locus was 13.46, mean observed heterozygosity was 0.55 and mean expected heterozygosity was 0.62. Bayesian clustering identified four subpopulations which generally corresponded to Western Russia, Western Europe, Eastern Europe and Sweden. All pairwise F-ST values were highly significant (p<0.001) with the greatest genetic differentiation detected between the Western Russian and the Western European subpopulations (F-ST = 0.12), and the smallest between the Swedish and Eastern European populations (F-ST = 0.04). The Swedish population also had the highest number of identical accessions, supporting the view that S. viminalis was introduced into this country and has been heavily influenced by humans. Q(ST) values were high for growth cessation and leaf senescence, and to some extent stem diameter, but low for bud burst time and shoot number. Overall negative clines between longitudinal coordinates and leaf senescence, bud burst and stem diameter were also found.
|
|
| 2. |
|
|
| 3. |
- Ghelardini, Luisa, et al.
(författare)
-
Genetic architecture of spring and autumn phenology in Salix
- 2014
-
Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 14, s. 31-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: In woody plants from temperate regions, adaptation to the local climate results in annual cycles of growth and dormancy, and optimal regulation of these cycles are critical for growth, long-term survival, and competitive success. In this study we have investigated the genetic background to growth phenology in a Salix pedigree by assessing genetic and phenotypic variation in growth cessation, leaf senescence and bud burst in different years and environments. A previously constructed linkage map using the same pedigree and anchored to the annotated genome of P. trichocarpa was improved in target regions and used for QTL analysis of the traits. The major aims in this study were to map QTLs for phenology traits in Salix, and to identify candidate genes in QTL hot spots through comparative mapping with the closely related Populus trichocarpa. Results: All traits varied significantly among genotypes and the broad-sense heritabilities ranged between 0.5 and 0.9, with the highest for leaf senescence. In total across experiment and years, 80 QTLs were detected. For individual traits, the QTLs explained together from 21.5 to 56.5% of the variation. Generally each individual QTL explained a low amount of the variation but three QTLs explained above 15% of the variation with one QTL for leaf senescence explaining 34% of the variation. The majority of the QTLs were recurrently identified across traits, years and environments. Two hotspots were identified on linkage group (LG) II and X where narrow QTLs for all traits co-localized. Conclusions: This study provides the most detailed analysis of QTL detection for phenology in Salix conducted so far. Several hotspot regions were found where QTLs for different traits and QTLs for the same trait but identified during different years co-localised. Many QTLs co-localised with QTLs found in poplar for similar traits that could indicate common pathways for these traits in Salicaceae. This study is an important first step in identifying QTLs and candidate genes for phenology traits in Salix.
|
|
| 4. |
|
|
| 5. |
- Hallingbäck, Henrik, et al.
(författare)
-
Association mapping in Salix viminalis L. (Salicaceae) - identification of candidate genes associated with growth and phenology
- 2016
-
Ingår i: Global Change Biology Bioenergy. - : Wiley. - 1757-1693 .- 1757-1707. ; 8:3, s. 670-685
-
Tidskriftsartikel (refereegranskat)abstract
- Willow species (Salix) are important as short-rotation biomass crops for bioenergy, which creates a demand for faster genetic improvement and breeding through deployment of molecular marker-assisted selection (MAS). To find markers associated with important adaptive traits, such as growth and phenology, for use in MAS, we genetically dissected the trait variation of a Salix viminalis (L.) population of 323 accessions. The accessions were sampled throughout northern Europe and were established at two field sites in Pustnas, Sweden, and at Woburn, UK, offering the opportunity to assess the impact of genotype-by-environment interactions (GxE) on trait-marker associations. Field measurements were recorded for growth and phenology traits. The accessions were genotyped using 1536 SNP markers developed from phenology candidate genes and from genes previously observed to be differentially expressed in contrasting environments. Association mapping between 1233 of these SNPs and the measured traits was performed taking into account population structure and threshold selection bias. At a false discovery rate (FDR) of 0.2, 29 SNPs were associated with bud burst, leaf senescence, number of shoots or shoot diameter. The percentage of accession variation explained by these associations ranged from 0.3% to 4.4%, suggesting that the studied traits are controlled by many loci of limited individual impact. Despite this, a SNP in the EARLY FLOWERING 3 gene was repeatedly associated (FDR<0.2) with bud burst. The rare homozygous genotype exhibited 0.4-1.0 lower bud burst scores than the other genotype classes on a five-grade scale. Consequently, this marker could be promising for use in MAS and the gene deserves further study. Otherwise, associations were less consistent across sites, likely due to their small estimates and to considerable GxE interactions indicated by multivariate association analyses and modest trait accession correlations across sites (0.32-0.61).
|
|
