An association genetics approach was used to examine individual genes and alleles at several loci responsible for complex traits controlling wood traits (cellulose, lignin, and 6C sugar) in European black poplar (Populus nigra). Due to fast growth, clonal propagation and availability of genomic resources have allowed us to investigate further genetic control of wood traits in the species. From thirty-nine candidate genes, 384 SNPs were successfully genotyped in a clonally replicated 288 P. nigra clone population. Only 50.5

Within the genus Salix, there are approximately 350 species native primarily to the northern hemisphere and adapted to a wide range of habitats. This diversity can be exploited to mine novel alleles conferring variation important for production as a bioenergy crop, but also to identify evolutionarily important genes, such as those involved in sex determination. To leverage this diversity, we created a mapping population by crossing six Salix species (S. viminalis, S. suchowensis, S. integra, S. koriyanagi, S. udensis, and S. alberti) to common male and female S. purpurea parents. Each family was genotyped via genotyping-by-sequencing and assessed for kinship and population structure as well as the construction of 16 backcross linkage maps to be used as a genetic resource for breeding and selection. Analyses of population structure resolved both the parents and F1 progeny to their respective phylogenetic section and indicated that the S. alberti parent was misidentified and was most likely S. suchowensis. Sex determining regions were identified on Salix chromosome 15 in the female-informative maps for seven of the eight families indicating that these species share a common female heterogametic ZW sex system. The eighth family, S. integra × S. purpurea, was entirely female and had a truncated chromosome 15. Beyond sex determination, the Salix F1 hybrid common parent population (Salix F1 HCP) introduced here will be useful in characterizing genetic factors underlying complex traits, aid in marker-assisted selection, and support genome assemblies for this promising bioenergy crop.

The breeding of hybrid cultivars of hemp (Cannabis sativa L.) is not well described, especially the segregation and inheritance of traits that are important for yield. A total of 23 families were produced from genetically diverse parents to investigate the inheritance of morphological traits and their association with biomass accumulation and cannabinoid yield. In addition, a novel classification method for canopy architecture was developed. The strong linear relationship between wet and dry biomass provided an accurate estimate of final dry stripped floral biomass. Of all field and aerial measurements, basal stem diameter was determined to be the single best selection criterion for final dry stripped floral biomass yield. Along with stem diameter, canopy architecture and stem growth predictors described the majority of the explainable variation of biomass yield. Within-family variance for morphological and cannabinoid measurements reflected the heterozygosity of the parents. While selfed populations suffered from inbreeding depression, hybrid development in hemp will require at least one inbred parent to achieve uniform growth and biomass yield. Nevertheless, floral phenology remains a confounding factor in selection because of its underlying influence on biomass production, highlighting the need to understand the genetic basis for flowering time in the breeding of uniform cultivars.

This study provides a new insight into Turkish Solix L. systematics, using a molecular phylogeny and numerical morphotnetric analysis approach. Despite its economic importance for bioenergy, there is to date no record of any extensive study on this Turkish willow species. twenty-four Solix species and one hybrid were subjected to molecular and morphometric evaluation, in which one gene region of the external transcribed spacer (ETS) of the 18S-26S nuclear ribosomal DNA and 11 morphologic-al characters were analyzed using a Bayesian Analysis of Beast program and Multiple Correspondence Analysis (MCA) in R. The results indicate that Salix species in -Turkey could be accurately classified at the subgenera level, considering the selected gene region and morphological traits (subgenus Sex and Vetrix). Life form, leaf shape (Dim 1) and bud scale (Dim 3) were highly discriminative at the subgenera level. The molecular and morphological data confirmed that the taxonomic position of Sailx ornplexica Os needs to be changed as subgenus Sallx. Additionally, the members of subgenus Softy, S. acmophylia and S. pentandroides were all clustered distantly from other species of the subgenus.