Carbohydrate status during somatic embryo maturation in Norway spruce

Abstract

The development of Norway spruce (Picea abies (L.) Karst.) somatic embryos on a maturation medium was accompanied by changes in nonstructural carbohydrate status. During embryo maturation, the content of total soluble sugars in the embryonal suspensor mass decreased and the partitioning between sucrose and hexoses changed considerably in favor of sucrose. Developing somatic embryos were mainly responsible for these changes. Osmotic stress caused by the presence of 3.75% polyethylene glycol (PEG) in the maturation medium (decrease in osmotic potential by 52.5 kPa) resulted in dramatic changes in the content of endogenous saccharides. There was a lower total carbohydrate content in the embryonal suspensor mass grown on the medium containing PEG in comparison with the untreated control. Isolated embryos from later stages of embryo development contained mainly sucrose with a small amount (20%) of fructose and nearly no glucose. A further increase in PEG concentration in the medium (7.5%; decrease in osmotic potential by 112.5 kPa compared to the maturation medium) led to a large increase in the total endogenous sugar content. This increase in sugars was a result of the enhanced content of sucrose, fructose, and glucose. The increased glucose content was in contrast to embryos grown on the medium with lower or no PEG content.

Effects of abscisic acid and an osmoticum on the maturation, starch accumulation and germination of Picea spp. somatic embryos

“…For example, Picea abies somatic embryos maturing on medium supplemented with sucrose at 17 or 34 g/L accumulated starch continuously from 3 to 7 weeks of culture, whereas embryos maturing on medium supplemented with 68 g/L of sucrose began to hydrolyse starch after 5 weeks of culture. These results are in perfect agreement with the findings of Lipavská et al (2000) that in P. abies somatic embryos, the starch content increased during approximately 5-6 weeks of cultivation on maturation medium and then, the starch content clearly decreased during weeks 7-8 of cultivation. Compared with this pattern, the pattern of accumulation and mobilisation of starch in P. abies somatic embryos that matured in the presence of 68 g/L of sucrose appeared to be more appropriate for embryonic development.…”

“…Sucrose is a source of carbon and energy and may participate in regulating the expression of genes that affect the embryonic maturation process (Lipavská et al 2000;Iraqi and Tremblay 2001;Iraqi et al 2005). This compound is often added to the culture medium to improve the maturation rate of somatic embryos (Lema-Rucińska et al 2013) and to increase the content of storage materials, such as starch and oligosaccharides, in the embryos (Kępczyńska 2006).…”

“…Between the mid-1980s and the early 1990s, the successful application of the somatic embryogenesis method for the micropropagation of both spruce species was achieved (Hakman et al 1985;Chalupa 1985;Budimir and Vujičić 1992). Thereafter, P. abies became the model species for the study of various aspects of conifer somatic embryogenesis Lipavská et al 2000;Malá et al 2009;Sun et al 2011;Bříza et al 2013;Hazubska-Przybył et al 2013). Few studies have investigated the somatic embryogenesis of P. omorika (Tramisak-Milaković et al 1999;Leljak-Levanić et al 2009;Hazubska-Przybył et al 2010), a more unique spruce species because of its endemic and relict character (Vujičić and Budimir 1995;Ballian et al 2006).…”

Induction, development and maturation of somatic embryos in Bunge’s pine (Pinus bungeana Zucc. ex Endl.)

“…PEG, as a non-permeating osmoticum, is able to create a culture environment similar to desiccation or partial desiccation, which favors embryo maturation. PEG increased endogenous ABA concentrations during somatic embryo maturation in white spruce (Kong and Yeung 1995) and raised total content of sugars in Norway spruce (Lipavská et al 2000). Supplementation of both ABA and PEG in media increased mature embryos significantly in coniferous species (Attree et al 1995;Li et al 1997;Kong and Yeung 1995;Klimaszewska et al 1997;Kong et al 1998;Pullman et al 2003).…”

Effects of Sugar Type and Concentration on Batu 55 Mandarin (Citrus reticulata Blanco.) Somatic Embryo Maturation

“…During maturation, carbohydrate supply was an important factor which influenced the quality and number of the embryo. Carbohydrate added into culture medium are used as carbon source, osmotic and also contribute in histodifferentiation of the somatic embryo by means of directing gene expression regulation (Lipavska et al 2000). Carbon source and concentration had a significant effect on the growth and development of the somatic embryo.…”