Avoidance of precipitation and carbohydrate breakdown in autoclaved plant tissue culture media

Abstract

The extent of breakdown of fructose and glucose derived from sucrose in the medium of Murashige and Skoog (1962) during autoclaving was investigated by polarographic measurement. Although not present in the original MS medium but often used in place of FeSO4 + Na2-EDTA, FeNa-EDTA was found to be primarily responsible for catalyzing the breakdown of these monosaccharides. It would therefore be good practice to autoclave FeNa-EDTA separate from the carbohydrate constituents of the medium in order to reduce the formation of toxic substances derived from the latter's breakdown. Autoclaving FeNa-EDTA separately has the additional advantage of preventing precipitation of certain micronutrient elements. Further precipitation can be avoided by autoclaving FeNa-EDTA and KH2PO4 together, but separately, from other components of the medium. By eliminating precipitation and minimizing the breakdown of monosaccharides during autoclaving, it is possible to improve the quality of the medium without resorting to sterilization by filtering.

Mineral uptake in tobacco leaf discs during different developmental stages of shoot organogenesis

“…For example, an excess of manganese can cause a deficiency in iron while excess iron or EDTA can reduce the uptake of zinc (Williams 1995). Furthermore, Schenk et al (1991) reported that during autoclaving, Fe-EDTA reacted with micronutrients and KH 2 PO 4 reacted Table 2 Pearson correlation coefficients (r) of dry weight and mineral depletion from SF culture media. Explant growth was based on dry weight data from Fig with calcium to form insoluble mineral complexes that were no longer available to the plant for growth and development.…”

Culture medium pH is influenced by basal medium, carbohydrate source, gelling agent, activated charcoal, and medium storage method

“…Heat sterilization can significantly alter medium pH by denaturation of proteins, hydrolysis of carbohydrates (Schenk et al 1991), and dissolution of salts (Behagel 1971).…”

Effects of autoclave-induced carbohydrate hydrolysis on the growth ofBeta vulgaris cells in suspension

“…Besides reducing the extent of sugar hydrolysis, autoclaving FeNa-EDTA separately also prevent the precipitation of certain micronutrient elements (Schenk et al 1991). The reason for autoclaving FeNa-EDTA together with NaH2PO 4 or CaCI 2 is to prevent the formation of precipitate between phosphate and calcium.…”

“…The changes in sucrose concentration due to volume changes does not affect appreciably the extent of its hydrolysis (Schenk et al 1991). Assuming, in addition, that precipitation is not a factor to be considered due to the brief duration of the trials, the variables in Table 1 can then be plotted to reveal their relation.…”

“…In our previous investigation (Hsiao & Bornman 1991b;Schenk et al 1991), it was demonstrated that FeNa-EDTA, besides forming precipitates with certain micronutrients in MS medium (Murashige & Skoog 1962), catalyses the breakdown of sugars. It was therefore suggested that the medium should be autoclaved in two parts: FeNa-EDTA plus KH2PO 4 and the remaining macro-and micronutrient elements together with sugars.…”