Genome‐wide association mapping for wood characteristics in <i><scp>P</scp>opulus</i> identifies an array of candidate single nucleotide polymorphisms

Abstract

Summary Establishing links between phenotypes and molecular variants is of central importance to accelerate genetic improvement of economically important plant species. Our work represents the first genome‐wide association study to the inherently complex and currently poorly understood genetic architecture of industrially relevant wood traits. Here, we employed an Illumina Infinium 34 K single nucleotide polymorphism ( SNP ) genotyping array that generated 29 233 high‐quality SNP s in c . 3500 broad‐based candidate genes within a population of 334 unrelated P opulus trichocarpa individuals to establish genome‐wide associations. The analysis revealed 141 significant SNP s ( α ≤ 0.05) associated with 16 wood chemistry/ultrastructure traits, individually explaining 3–7% of the phenotypic variance. A large set of associations (41% of all hits) occurred in candidate genes preselected for their suggested a priori involvement with secondary growth. For example, an allelic variant in the FRA 8 ortholog explained 21% of the total genetic variance in fiber length, when the trait's heritability estimate was considered. The remaining associations identified SNP s in genes not previously implicated in wood or secondary wall formation. Our findings provide unique insights into wood trait architecture and support efforts for population improvement based on desirable allelic variants.