Association Analysis of Growth, Disease and Developmental Properties, and Microbiome Communities, in Populus deltoides

Populus deltoidesis a potential bioenergy crop because of its fast growth and wide adaptation to the Midwest and Southern US. In order to uncover genes that regulate traits that are critical for development of a commercial crop we have been characterizing a population of 500 Populus deltoidesindividuals. This genetically unstructured population has been clonally propagated and established in field and greenhouse trials, and all individuals were genotyped by sequence capture of all genes expressed in vegetative tissues. To widen the scope of the genotyping effort, we have now expanded the genotyping to the entire genome by applying novel methods of imputation. Phenotype measurements were collected from the population under field and greenhouse conditions over multiple years and is ongoing. An initial genome-wide association study (GWAS) for wood quality traits uncovered a suite of associated polymorphisms, including a major locus that significantly impact the ration of syringyl to guaiacyl lignin monomers. The phenotypic and GWAS analysis has now expanded to growth properties measured in the field, as well as several developmental properties that are critical for development of elite poplar cultivars (number of branches and the rooting ability). In addition, disease resistance to pathogens including Sphaerulina leaf spot and Melampsora rust have been quantified and analyzed, showing moderate to high heritability levels. Finally, we have also measured the diversity of the leaf microbiome in the poplar population, for future analysis of its contribution to plant phenotypes. The outcome from these association analyses will be presented.