Treatment Of Suspension Cultures Research Articles

Induction of triterpene biosynthesis by elicitors in suspension cultures of Tabernaemontana species

Treatment of suspension cultures of some Tabernaemontana species (Apocynaceae) with elicitors (e.g. cellulase, Candida albicans) result in a rapid de novo production of antimicrobial active triterpenes. The triterpenes are identified as ursene carboxylic acid derivatives. These triterpenes are not produced by an elicited cell suspension culture of Catharanthus roseus, another Apocynaceae.

Growth retarding effects of the herbicide difenzoquat

The growth-regulating properties of the herbicide Difenzoquat (1,2-dimethyl-3,5-diphenyl-1-H-pyrazolium methyl sulfate) were investigated in seedlings and cell suspension cultures of sunflower (Helianthus annuus L.). Application of 10 μg or more Difenzoquat to the apex of seedlings resulted in a transient inhibition of internode elongation. Application of GA3 to treated seedlings resulted in enhanced internode elongation but did not reverse the degree of growth inhibition elicited by Difenzoquat. Endogenous gibberellin levels were estimated by bioassay and were qualitatively and quantitatively similar in extracts from control and treated seedlings. Treatment of suspension cultures of sunflower cells with 1 μM or more Difenzoquat resulted in an inhibition of cell division (dry-matter accumulation). Neither GA3 nor a mixture of sterols (cholesterol, β-sitosterol, and stigmasterol) alone or in combination was able to overcome this inhibition of cell division. It was concluded that the growth-retarding activity of Difenzoquat was the result of its action at the cellular level and was not mediated by inhibition of gibberellin biosynthesis.

Oxidative degradation of chlortoluron, propiconazole, and metalaxyl in suspension cultures of various crop plants

The metabolism of chlortoluron, ( N′-(3-chloro-4-methylphenyl)- N,N-dimethylurea), propiconazole (1-[2-(2′,4′-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl-methyl]- 1H-1,2,4-triazole), and metalaxyl ( dl- N-(2,6-dimethylphenyl)- N-(2′-methoxyacetyl) alanine methyl ester) was investigated in suspension cultures of crop species for which differences in metabolism had been demonstrated at the intact plant level. Uptake and metabolism of chlortoluron by cultures of Italian rye-grass ( Lolium multiflorum) was slow, the metabolites detected (42% of applied radioactivity after 13 days) being products of ring methyl oxidation and N-monodealkylation reactions. In sharp contrast, metabolism in a cotton ( Gossypium hirsutum) suspension culture was extremely fast (72% after 4 hr) and was attributed to extensive N-didealkylation in addition to rapid ring methyl oxidation. This rate of metabolism also implied a very rapid uptake of chlortoluron by the cotton culture. 14C-labelled propiconazole became rapidly associated with cells of wheat ( Triticum aestivum) and rice ( Oryza sativa) following treatment of suspension cultures. Uptake was initially more rapid in the rice culture (36% of applied radioactivity after 8 h compared to 19% for wheat) which, together with a slower rate of metabolism, resulted in more unchanged propiconazole being associated with rice cells. On a parts-per-million basis these results indicated an apparent 10-fold accumulation of propiconazole in rice cells compared to 5-fold in the wheat culture. Propiconazole metabolite patterns were similar in cultures of both species and indicated side-chain hydroxylation as the principal pathway. Uptake of metalaxyl was slow in suspension cultures of both lettuce and potato (≅ 20% after 17 days). Subsequent metabolism was also slow but appeared to be limited by the poor rate of uptake. Both cultures were found to be similarly versatile with respect to metabolic attack on metalaxyl, which included ring methyl hydroxylation, aryl hydroxylation, ester cleavage, ether cleavage ( O-dealkylation), and N-dealkylation (side-chain cleavage), the hydroxylation reactions being quatitatively the more important. The results for all three pesticides are compared to those obtained previously from studies with intact plants of the same species.

Ultrastructure of acridone alkaloid idioblasts in roots and cell cultures of Ruta graveolens

Histological analysis of Ruta graveolens L. roots and in vitro grown cell suspensions revealed idioblasts with vacuoles containing clusters of droplets thought to be the storage compartment of acridone alkaloids. These idioblasts contained numerous vacuoles of varying sizes rather than the large, single, central vacuole characteristic of most adjacent parenchyma cells. The structure of idioblasts in roots and suspension cultures was identical. Treatment of suspension cultures with fungal elicitors known to increase alkaloid accumulation greatly did not affect the structure of idioblasts.

Significance of a common epitope of plant and animal endomembranes

A rat monoclonal antibody that was raised against a common epitope on bean (Phaseolus vulgaris) endomembranes has been shown to cross-react with microsomal polypeptides from a number of plant and animal species. Immunoblotting has shown that the epitope is present on a large subset of polypeptides on microsomes of five animal species. The antigenic site appears to be accessible on intact bean membranes since it is readily digested by trypsin. The epitope is probably not derived post-translationally since the same Mr range is immunoprecipitated from polypeptides newly synthesized in vivo and in vitro. The polypeptides in bean appear to be regulated independently, one of Mr 58,000, in particular, was highly induced by treatment of suspension cultures with fungal elicitor. Preincubation of membranes enriched with endoplasmic reticulum and Golgi apparatus with the antibody blocks transfer of radioactivity from one compartment to the other in vitro. The common antigenic site could possibly be concerned in recognition or some fusion event during membrane trafficking within the cell.