Artemisinin is a plant natural product produced by Artemisia annua and the active ingredient in the most effective treatment for malaria. Efforts to eradicate malaria are increasing demand for an affordable, high-quality, robust supply of artemisinin. We performed deep sequencing on the transcriptome of A. annua to identify genes and markers for fast-track breeding. Extensive genetic variation enabled us to build a detailed genetic map with nine linkage groups. Replicated field trials resulted in a quantitative trait loci (QTL) map that accounts for a significant amount of the variation in key traits controlling artemisinin yield. Enrichment for positive QTLs in parents of new high-yielding hybrids confirms that the knowledge and tools to convert A. annua into a robust crop are now available.

Background: An increased understanding of leaf area development is important in a number of fields: in food and non-food crops, for example short rotation forestry as a biofuels feedstock, leaf area is intricately linked to biomass productivity; in paleontology leaf shape characteristics are used to reconstruct paleoclimate history. Such fields require measurement of large collections of leaves, with resulting conclusions being highly influenced by the accuracy of the phenotypic measurement process.

Fast-growing hybrid poplar (Populus spp.) have potential as a short-rotation coppice crop grown for biomass energy. This work identifies traits for fast growth studied in an American interspecific pedigree derived from Populus trichocarpa Torr. & A. Gray × Populus deltoides Marsh. grown in the United Kingdom for the first time. The biomass yield after the first coppice rotation was estimated to range from 0.04 to 23.68 oven-dried t·ha–1·year–1. This great range suggests that genotypes from this pedigree may be used to understand the genetic basis of high yield in short-rotation coppice, which would be advantageous for informing breeding programs for biomass crops. Relationships between stem, leaf, cell traits, and biomass yield were investigated. Partial least-squares analysis was used to order the traits by importance. The traits most influential on biomass were maximum stem height throughout the growing season, basal diameter, number of stems, and number of sylleptic branches, which showed high heritability, indicating excellent potential for breeding programs. The leaf traits, leaf area, number of leaves on the leading stem, and plastochron index were also associated with an increase in biomass, leading to a better understanding of this trait.

Populus is a genus of fast growing trees that may be suitable as a bioenergy crop grown in short rotation, but understanding the genetic nature of yield and genotype interactions with the environment is critical in developing new high-yield genotypes for wide-scale planting. In the present study, 210 genotypes from an F 2 population (Family 331; POP1) derived from a cross between Populus trichocarpa 93-968 and P. deltoides ILL-129 were grown in southern UK, central France and northern Italy. The performance of POP1, based upon first-and second-year main stem traits and biomass production, improved from northern to southern Europe. Trees at the Italian site produced the highest mean biomass ranging from 0.77 to 18.06 oven-dried tonnes (ODT) ha −1 year −1 , and the UK site produced the lowest mean biomass ranging from 0.18 to 10.31 ODT ha −1 year −1 . Significant genotype×environ-ment interactions were seen despite heritability values across sites being moderate to high. Using a pseudotestcross analysis, 37 quantitative trait loci (QTL) were identified for the maternal parent and 45 for the paternal parent for eight stem and biomass traits across the three sites. High genetic correlations between traits suggested that collocating QTL could be inferred as a single pleiotropic QTL, reducing the number of unique QTL to 23 and 24 for the maternal and paternal parent, respectively. Additive genetic effects were seen to differ significantly for eight QTL on the maternal map and 20 on the paternal map across sites. An additive main effects and multiplicative interaction analysis was carried out to obtain stability parameters for each trait. These parameters were mapped as QTL, and collocation to trait QTL was accessed. Two of the eight stability QTL collocate to trait QTL on the maternal map, and 8 of the 20 stability QTL collocate to trait QTL on the paternal map, suggesting that a regulatory gene model is prevalent over an allele sensitivity model for stem trait stability across these environments.

Background: Concern over land use for non-food bioenergy crops requires breeding programmes that focus on producing biomass on the minimum amount of land that is economicallyviable. To achieve this, the maximum potential yield per hectare is a key target for improvement. For long lived tree species, such as poplar, this requires an understanding of the traits that contribute to biomass production and their genetic control. An important aspect of this for long lived plants is an understanding of genetic interactions at different developmental stages, i.e. how genes or genetic regions impact on yield over time.