Frequency of somaclonal variation in plants of black spruce (Picea mariana, Pinaceae) and white spruce (P. glauca, Pinaceae) derived from somatic embryogenesis and identification of some factors involved in genetic instability

Abstract

Plants of black spruce (Picea mariana, N = 7047 individuals) and white spruce (P. glauca, N = 3995 individuals) were regenerated from a total of 87 clones over a 5-yr period by somatic embryogenesis to study factors that might be associated with the appearance of variant phenotypes. Morphological evaluation of the plants showed several types of variation. These variations were grouped into nine types: dwarfism (type A), reduced height with various form anomalies (types B, C, and D), needle fasciation (type E), abnormality in tree architecture (type F), variegata phenotype (type G), and plants with an overall regular morphology but smaller than normal plants (type H). Plagiotropic plants were also observed (type I). Each plant from types A to H (except type C where no plants survived more than 6 mo) had retained its phenotype over 4-5 yr of growth. Some of the variant types could be related to chromosomic instability: chromosome counts showed aneuploid cells for type-A and type-D plants. The type I (plagiotropism) was not related to genetic instability but rather to physiological disorders. In total, spruce variants of types A-H were obtained at relatively low frequencies, i.e., 1.0% (39/3995) for white spruce and 1.6% (110/7047) for black spruce. Statistical analyses, conducted with family, clone, and time in maintenance as variables, showed that clone was the most important source of genetic instability followed by time in maintenance.

High embryogenic ability and regeneration from floral axis of Amorphophallus konjac (Araceae)

“…The stability reported here is not described in other species, in which polyploidisation was found during somatic embryogenesis (23)(24)(25)(26)(27). Endemann [27] found that tetraploidy occurs 8% of the clones tested over a culture period of 7 years in Quercusrobur.…”

“…The samples were fixed in FAA (formaldehyde/acetic acid/ ethanol=10:5:85 v/v/v) for 48 h, followed by 30 min of dehydration at increasing ethanol gradations [25,50,75,95, 100% (v/v)]; dehydration was performed twice for each step. Ethanol was replaced by gradual dilution with trichloroethane solution.…”

Analysis of genetic stability at SSR loci during somatic embryogenesis in maritime pine (Pinus pinaster)

“…In our study with P. pinaster, after 12 months of ex vitro conditions, 50% of the plants in which plagiotropism was initially detected and started to revert to orthotropism. Similarly, plagiotropic growth was also initially detected in plants of Larix (Ewald 1999) and in Picea (Tremblay et al 1999) propagated by SE, but after approximately 5 years a normal orthotropic growth was completely restored in these plants.…”

Técnicas moleculares para la detección de variantes somaclonales

“…(ahloowalia y sherington , osuji et al 1997, Tremblay et al 1999, mehta y angra 2000); (b) patrones isoenzimáticos, que se basan en la presencia de isoformas de enzimas específicas, que tienen la misma actividad, pero con diferente estructura molecular (Jarret y Litz 1986, chen et al 1998, müller-starck 1998, seo et al 2004; (c) los basados en proteínas de reserva de las semillas (maddock et al 1985, campa et al 2004, martín-cuevas et al 2004); y (d) aquellos basados en el ADN, los cuales constituyen el tema específico de esta revisión (Picca et al 2004).…”

“…Varios autores recomiendan que, al usar marcadores moleculares, deben combinarse al menos dos metodologías para una corroboración exacta y así evitar falsos positivos (ooms et al 1987, speeckaert y Jacobs 1988, Jiménez 1996, osuji et al 1997, chen et al 1998, Tremblay et al 1999, Feuser et al 2003, Kubis et al 2003.…”