Physiological Effects of Colchicine on Growth and Metabolism of Mungbean (Phaseolus aureus L.) Seedlings and α-Amylase Production in Rice (Oryza sativa L.) Endosperm

The Biochemistry of Alkaloids

“…The advantages of ricinine as an object of study are that the plant is easily grown and that it contains high concentrations of only one alkaloid. Derivation of the pyridine ring of ricinine from nicotinic acid or nicotinamide was first shown by Leete and Leitz [99] and has since been amply demonstrated by others [195]. In young seedlings, the quantity per plant may increase up to 50-fold within a week after planting [197].…”

“…It is clear that pyridine nucleotide metabolism is closely related to ricinine biosynthesis because inhibitors of the pyridine nucleotide cycle cause parallel inhibition of ricinine biosynthesis [72]. Arguing against the essentiality for nucleotides in the ricinine pathway is the observation that when nicotinamide labeled with P'N] in the amide group and [3H] at positions 2, 4, 5, and 6 of the ring was fed to castor bean plants, the amide nitrogen and the ring were incorporated as an intact unit [195]. It thus seems likely that the pathway to ricinine branches off from the pyridine nucleotide cycle; but these branches may occur at more than one point, giving a metabolic grid [72,198].…”

“…The two methyl groups of ricinine are, expectedly, derived from methionine [25] or formate [195]; but the point in the sequence when they are added is unknown, as is the point at which the pyridine ring becomes oxygenated, and the point at which the amide group is dehydrated to a cyano group. Castor bean seedlings (as well as other plants of the Euphorbiacae) contain an enzyme that oxidizes 1-alkylnicotinonitriles to the corresponding 4and 6-pyridones [34][35][36].…”

“…Intracellular transport of proteins is a process dependent on micro tubules and inhibited by colchicine [40,170]. The inhibition of normal or gibberellin-induced elongation might be a result of colchicine's effect on cortical microtubules that control orientation of cellulose microfibrils [107,195,224]. Related effects may be the inhibition by colchicine of cholesterol synthesis [187], or ornithine decarboxylation [42], of the release of norepinephrine from hypogastric nerve [26]; and its stimulation of triglyceride synthesis [187], and of histamine sensitivity [219].…”

Effects of colchicine on carrot callus — growth and energy status

“…Plant cells require high concentrations of colchicine (1.25 x 10 -s to 7.2 x 10 -3 M) to depolymerize microtubules, and these concentrations may also affect metabolic processes unrelated to microtubules [6]. The biochemical action of colchicine is practically unknown compared to its cytological action [18].…”