Structural genomic variations and their effects on phenotypes in Populus

DNA copy numbers have recently emerged as an important new marker system. In the absence of a contiguous reference genome, alternative detection systems such as the comparative hybridization method have been used to detect copy number variations (CNVs). With the advent of chromosome-level resolved reference genomes based on the incorporation of long-read sequencing and powerful bioinformatics pipelines, comprehensive detection of all structural variations (SVs) in the poplar genome is now within reach. Gene CNVs and their inheritance are important because they can cause dosage effects in phenotypic variations. These are potent genetic markers that should be considered in complex trait variation such as growth and adaptation in poplar. SVs such as CNVs could be used in future genomic selection studies for poplar, especially in cases when heterosis increases hybrid performance (hybrid vigor). This Chapter reports recent findings on SVs in natural populations of Populus spp. as well as on artificially induced SVs in poplar to understand their potential importance in generating a considerable amount of phenotypic improvement. The Chapter concludes with an outlook on the future implementation of knowledge on SVs in poplar crop breeding. ### Competing Interest Statement The authors have declared no competing interest.