Storage lipid dynamics in somatic embryos of Norway spruce (Picea abies): histochemical and quantitative analyses

Abstract

Adequate storage compounds are a prerequisite for successful development during the later stages of somatic embryogenesis; however, the critical amount of reserves below which somatic embryos fail to mature and germinate has not been determined. We analyzed storage lipids during Norway spruce (Picea abies (L.) Karst.) somatic embryogenesis. As maturation progressed, lipids, which were stored as lipid bodies in the cytoplasm, were localized first in suspensor cells of the early embryos, and later in the embryonic root pole, superficial layers of the hypocotyl and in cotyledons. The concentration of total lipids exhibited marked variation, with values peaking during cotyledon development and then decreasing during maturation. Linoleic (18:2), oleic (18:1), palmitic (16:0) and 5,9-octadecenic (5,9-18:2) acids were the most abundant fatty acids in embryos. As embryos developed, linoleic acid concentration increased slightly, whereas oleic acid concentration decreased. Oleic acid was the most prominent component of the fatty acid spectrum in isolated dormant zygotic embryos and megagametophytes. Addition of 5% polyethylene glycol to the medium during somatic embryo maturation caused a shift in the fatty acid spectrum toward that of zygotic embryos. During maturation, changes in the exogenous carbohydrate supply had no significant effect on total lipid concentration in mature embryos. A marked decrease in lipid concentration was detected during desiccation, indicating the importance of adequate lipid reserves during this developmental stage. The lipid content of zygotic embryos differed considerably with harvest year and location, suggesting that zygotic embryo data cannot be an indicator of somatic embryo quality.

Conifer somatic embryogenesis – an efficient plant regeneration system for theoretical studies and mass propagation

“…The structural and morphological changes during maturation are accompained by biochemical changes as accumulation of storage reserves (Brownfield et al 2007;Grigova et al 2007;Kubes et al 2014) in the form of protein and lipid bodies and the transport of protein bodies is mediated by Golgi apparatus (Hakman 1993). The storage proteins can also be markers of somatic embryo development (Teyssier et al 2014).…”

Study of Abies somatic embryogenesis and its application

“…The decrease in total carbohydrate as well as the accumulation of sucrose in later developing stages was a common features in both systems (Konrádová et al 2002). The concentrations of total lipids exhibited marked variation during maturation of Picea abies somatic embryos, indicating the importance of lipid reserves during embryo development (Svobodová et al 1999, Grigová et al 2007). The accumulation of high levels of polyamines in Picea abies somatic embryos may be causally linked to their lower germinability than in zygotic embryos (Gemperlová et al 2009).…”

Testing of Algerian fir zygotic and somatic embryos on defence reactions in vitro

“…The decrease in total carbohydrate as well as the accumulation of sucrose in later developing stages was a common features in both systems (Konrádová et al 2002). The concentrations of total lipids exhibited marked variation during maturation of P. abies somatic embryos, indicating the importance of lipid reserves during embryo development (Svobodová et al 1999, Grigová et al 2007.…”