Characterization of Sitka × interior spruce hybrids: A biotechnological approach to seedlot determination

The Nass Skeena Transition is an area located in British Columbia (BC), Canada, where a large introgression zone occurs between Sitka spruce (Picea sitchensis (Bong.) Carr.) and interior spruce (white spruce, Picea glauca (Moench) Voss × Engelmann spruce, Picea engelmannii Parry ex. Engelm.). When these species hybridize in this transition area, forestry programs face special problems in identifying seedlots that have the desired genetic makeup of source material collected from traditional seed zones. This paper presents an overview of a program that combined the disciplines of molecular genetics and ecophysiology to assist in defining the genetic makeup of seedlots based on DNA analysis results. Research first identified chloroplast, mitochondrial and nuclear DNA probes that were used to estimate species components for Sitka × interior spruce hybrid seedlots. Seedlings produced from Sitka × interior spruce hybrid seedlots were then characterized for ecophysiological parameters of drought tolerance, freezing tolerance and gas exchange patterns. DNA analysis results were then compared to ecophysiological parameters and findings indicated that seed source DNA profiles were related to drought tolerance throughout the year, freezing tolerance during fall acclimation and gas exchange patterns during the summer season. Using standard seed zone deployment practices in conjunction with these scientific findings provided a more comprehensive approach for defining seed transfer guidelines of Sitka and interior spruce populations. This program provided an example of how the field of biotechnology was used to assist in defining a seed deployment strategy for a region where introgression is a common occurrence between Sitka and interior spruce populations. Key words: biotechnology, molecular genetics, ecophysiology, Sitka spruce, interior spruce, introgression zone, seedlot deployment.