Creation and Genomic Analysis of Irradiation Hybrids in Populus

Establishing efficient functional genomic systems for creating and characterizing genetic variation in forest trees is challenging. Here we describe protocols for creating novel gene-dosage variation in Populus through gamma-irradiation of pollen, followed by genomic analysis to identify chromosomal regions that have been deleted or inserted in each F1 individual. Irradiated pollen is used in a controlled, interspecific cross to create F1 progeny that carry deletions and insertions of chromosomal regions. These insertions and deletions result in novel changes in gene dosage that in turn affect both qualitative and quantitative phenotypic traits. The protocols described here outline the processes involved in optimizing irradiation levels and performing controlled crosses, sowing seed and propagating seedlings, and genome-wide sequence-based analysis of deletions and insertions in the F1 progeny. The same approach could be applied to other vegetatively propagated species. © 2016 by John Wiley & Sons, Inc.