Propagation of interior spruce by somatic embryogenesis

Abstract

To apply somatic embryogenesis to clonal propagation of forest species, the technique must be applicable to a broad range of genotypes and allow efficient regeneration of phenotypically normal plants. Seventy-one lines (genotypes) of embryogenic cultures from six open-pollinated families were obtained by culturing immature embryos of interior spruce. Interior spruce represents a mixture of two closely related species, Piceaglauca (Moench) Voss and Piceaengelmannii Parry, from the interior of British Columbia where they hydridize with one another. The abscisic acid dependent developmental profile (the proportion of rooty embryos, shooty embryos, precociously germinating embryos, and mature embryos over a range of abscisic acid concentrations) differed among genotypes, but in general, production of mature somatic embryos was highest at 40 and 60 μM abscisic acid. Treatment of mature embryos with a high relative humidity treatment resulted in partial drying of the embryos and upon rehydration, markedly enhanced germination of the eight genotypes tested. Within 1 week of being placed under germination conditions, somatic embryos treated with the high relative humidity treatment showed 80–100% germination for 12 of the genotypes, and most genotypes had germination rates of greater than 40%. Survival of "emblings" (germinants from somatic embryos) following transfer to soil, acclimatization, and first season's growth in the nursery was 80% or greater for most genotypes. Over 1200 emblings were tested for nursery performance, representing the first large-scale evaluation of conifer somatic embryos under exvitro conditions. Growth rates, final height, shoot and root morphology, and frost hardiness were similar for emblings and seedlings following the first growing season. These results indicate that somatic embryogenesis can be used for the production of planting stock for a range of interior spruce genotypes.

Morphogenic Aspects of Somatic Embryogenesis

“…Similarly, a high sucrose concentration (9%) during the first half of maturation, followed by a lower sucrose concentration (6%) during the second half increased dry weight accumulation and conversion frequency [241]. In support of this, spruce somatic embryos matured under conditions that promote abundant reserve accumulations [223,244] exhibit good conversion rates and vigor.…”

Effect of partial drying and desiccation on somatic seedling quality in Norway and Serbian spruce

“…To date, for some conifer species, the effect of various environmental factors on the germination of somatic embryos has been studied (Uddin et al 1989;Webster et al 1990;Hay and Charest 1999;Hogberg et al 2001). Some of the first factors studied were: medium composition, light versus dark culture, and position of embryos on the media (Uddin et al 1989).…”

Somatic embryogenesis as a main tool in forest biotechnology

“…Los ensayos en campo para evaluar el comportamiento de las plantas micropropagadas más extendidos son los realizados en especies de mayor valor comercial, pudiendo destacarse los estudios realizados en Picea glauca (Webster et al, 1990;Grossnickle et al, 1992), en Picea abies (Ruaud y Pâques, 1995) y en Pseudotsuga menziesii (Benowicz et al, 2002). En angiospermas, la aplicación comercial más extendida se encuentra en la palma de aceite, Elaeis guineensis (Khaw et al, 1998).…”