Propagation of Ornamental Plants
21(1): 27-40, 2021
SOMATIC EMBRYOGENESIS OF WEEVIL RESISTANT PHENOTYPES OF SITKA SPRUCE, PICEA SITCHENSIS (BONG.) CARR.
Patrick von Aderkas1,4*, Natalie Prior1, Stefan A. Little1, Taylor Holt1, Emma Creasy1, Justin Whitehill2, John King3, and Lisheng Kong1
1 Centre for Forest Biology, University of Victoria, 1700 Finnerty Road, Victoria BC V8W 3N5, Canada, Fax: + 250 721 7120, *E-mail: pvonader@uvic.ca 2 Christmas Tree Genetics Program, Department of Forestry and Environmental Resources, North Carolina State University, Raleigh NC 27607, USA 3 British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development, Victoria, BC V8W 9C2, Canada 4 Centre for Forest Biology, University of Victoria, 1700 Finnerty Road, Victoria, BC V8W 3N5, Canada
A somatic embryogenic system was created using material from the British Columbia Ministry of Forests and Range’s Sitka Spruce (Picea sitchensis (Bong.) Carr) breeding program for resistance to the white pine weevil (Pissodes strobi Peck). The goal was to provide a system that could aid in understanding the phenotypic and genotypic variation among these traits. Embryogenic lines were derived from controlled crosses of parental genotypes previously ranked for the abundance of three anatomical traits: sclereid cells, constitutive resin canals, and traumatic resin canals. The number of filled seeds per cone from controlled pollinations was low compared to open-pollinated material. The mean induction rate (to embryogenic cultures) was 8%, ranging from 0% to 51% by cross. Of 135 genotypes, 88% produced mature embryos. Nearly all (44 of 45) genotypes germinated, with a mean germination rate of 80%. The overall conversion rate of somatic embryos to plants was 5.5%. A novel method of cryopreservation involving a temperature pretreatment while not requiring dimethyl sulfoxide was used successfully to recover somatic embryos. High sclereid abundance in leader shoots, typical of resistant phenotypes, was observed in ten-year-old trees derived from somatic embryos multiplied from seed of resistant breeding stock.
Key words: constitutive weevil resistance, cryopreservation, in vitro multiplication, Pissodes strobi, sclereids, Sitka spruce breeding
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