Analysis of carbohydrate metabolism enzymes and cellular contents of sugars and proteins during spruce somatic embryogenesis suggests a regulatory role of exogenous sucrose in embryo development

Abstract

Carbohydrate metabolism was investigated during spruce somatic embryogenesis. During the period of maintenance corresponding to the active phase of embryogenic tissue growth, activities of soluble acid invertase and alkaline invertase increased together with cellular glucose and fructose levels. During the same time, sucrose phosphate synthase (SPS) activity increased while sucrose synthase (SuSy) activity stayed constant together with the cellular sucrose level. Therefore, during maintenance, invertases were thought to generate the hexoses necessary for embryogenic tissue growth while SuSy and SPS would allow cellular sucrose to be kept at a constant level. During maturation on sucrose-containing medium, SuSy and SPS activities stayed constant whereas invertase activities were high during the early stage of maturation before declining markedly from the second to the fifth week. This decrease of invertase activities resulted in a decreased hexose:sucrose ratio accompanied by starch and protein deposition. Additionally, carbohydrate metabolism was strongly modified when sucrose in the maturation medium was replaced by equimolar concentrations of glucose and fructose. Essentially, during the first 2 weeks, invertase activities were low in tissues growing on hexose-containing medium while cellular glucose and fructose levels increased. During the same period, SuSy activity increased while the SPS activity stayed constant together with the cellular sucrose level. This metabolism reorganization on hexose-containing medium affected cellular protein and starch levels resulting in a decrease of embryo number and quality. These results provide new knowledge on carbohydrate metabolism during spruce somatic embryogenesis and suggest a regulatory role of exogenous sucrose in embryo development.

Polyphenols Distribution and Reserve Substances Analysis in Cocoa Somatic Embryogenesis

“…They highlighted seven categories: (1) carbohydrate metabolism; (2) energy metabolism; (3) amino acid metabolism; (4) genetic information processing; (5) cellular processes; (6) stress response; and (7) defense. As described above, embryogenesis is a complex developmental process which is extensively based on carbohydrate metabolism (including sugar conversion), as previously reported in Picea glauca (Iraqi and Tremblay, 2001), Cyclamen persicum (Rode et al, 2012) and in Phoenix dactylifera (Sghaier-Hammami et al, 2009). The explanation for extensive carbohydrate metabolism is the heavy energy demand required for metabolic processes that occur during cell division and elongation (Kroon and Williams, 1999).…”

Storage protein dynamics in zygotic and somatic embryos of white fir

“…Enzyme activity rather than protein profiles seems to be a suitable tool in monitoring the individual stages of zygotic or somatic embryo development. An increase in invertase activity during maturation stage of Picea mariana has for example been observed by Iraqi & Tremblay (2001). In Picea glauca, an increased activity of adenine and uridine salvage enzymes was reported during conversion of somatic embryos into plantlets as well as an increase of dehydroascorbate activity during maturation and germination of somatic embryos of the species .…”

Effect of Culture Medium in Callogenesis from Adult Walnut Leaves (Juglans regia L.)

“…Although these results establish that the calli with better morphogenic characteristics in terms of tissue organization originate from the BTM culture media, it is still necessary to obtain a manifestation of these structures in formation at the surface level, which is associated with, among other factors, the induction time, the type and concentration of growth regulators, genotype and the type and source of carbohydrates (Scaltsoyiannes, 1997;Fernández et al, 2000;Iraqi and Tremblay, 2001). In other species, such as Olea europaea L. and Decalepis hamiltonii Wight & Arn, it has been established that a manifestation stage is necessary posterior to the callogenic induction stage, in which one or more components of the media are modified, and it is in this stage that it is possible to differentiate the calli that is obtained in induction (Shibli et al, 2001;Giridhar et al, 2004;Bunn et al, 2005).…”