Induction of somatic embryos of celery by control of gaseous compositions and other physical conditions

Abstract

The celery (Tall Utah, Apium graveolens var. dulce) was adopted as a model system to investigate effective methods for enhancing embryogenesis. The focus was placed on attaining the optimum gaseous composition and the mixing intensity and viscosity of culture systems. The mixing intensity was investigated by using creased flasks and evaluated by shear force index (SFI). By using different closures with different ventilation coefficients, Kw, to adjust the gaseous composition in the flasks, it was found that embryo frequency (EF) increased with high P O 2 or low ethylene concentration in the headspace of the culture flasks. Cultivating the embryogenic cells under controlled ethylene concentrations depressed EF at ethylene concentrations higher than 0.08 ppm. Moreover, 0.1 lM of CoCl 2 remarkably repressed the ethylene formation in the culture medium and enhanced EF. P CO 2 and P O 2 around 3% and 30%, respectively, favored EF. For non-creased flasks, addition of CMC (carboxymethyl cellulose) decreased the EF and DO level of the medium, due to lowered mass transfer rate attributed to high viscosity. For creased flasks, supplementation of 0.4 g/ 100 ml CMC reduced the ill-effects of high shear stress and maximized EF (7.22%). Our results are potentially applicable to other species and largescale embryo production systems.

Influence of culture vessel characteristics and agitation rate on gaseous exchange, hydrodynamic stress, and growth of embryogenic cork oak (Quercus suber L.) cultures

“…It is known that increased mixing favours mass transfer and gaseous exchange (Sajc et al 2000;Shimazu and Kurata 2003;Huang et al 2006), factors that explain the above relationship between high biomass production and proliferation, and the high K L a and SFI values.…”

“…From the second week, the DO in the sealed flasks was close to the critical level for plant cell cultures (Dubuis et al 1995) and certainly limited growth. However, other effects related to the suppression of gaseous exchange may also have been in operation, such as the accumulation of ethylene (Huang et al 2006).…”

“…The SFI was determined using the method of Tanaka (1981), with the modifications proposed by Huang et al (2006). This index relies on the fact that β-naphthol has a density similar to that of plant cells.…”

“…The design of the flask, its closing system, and the degree of agitation determine the amount of gaseous exchange that can take place, the degree of mixing that can be achieved, and the level of hydrodynamic stress suffered. All these factors can, therefore, affect the growth and development of embryogenic cultures and the frequency with which somatic embryos can differentiate (Huang et al 2001(Huang et al , 2006Shimazu and Kurata 2003). For the production of embryogenic suspensions, Finer (1994) recommended the use of baffled Erlenmeyer flasks; these facilitate agitation and therefore promote the dissociation of tissues and gaseous exchange.…”

Effects from shear stress on morphology and growth of early stages of Norway spruce somatic embryos

“…The gas balance inside the bioreactor poses a challenge both in terms of obtaining a gas-balance permissible to somatic embryo development (Huang et al, 2006), as does managing the inhibitory shear stress from gas purging of the bioreactor (Bieniek et al, 1995). In our study, we have not studied the effect of the gas balance inside the flow cell.…”