Histochemical and Quantitative Observations on the Distribution of Galiosinase in the Shoots of Stellateae

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Abstract
A histochemical method for the detection of the specific glycosidase galiosinase in plant tissues is described. A colorimetric method for the estimation of the enzyme is described. The distribution of the enzyme in the shoots of 14 species of Stellateae, representing genera, has been investigated. In the leaves and stem galiosinase occurs in high concentrations in the cambium and in lower concentrations in the developing phloem and xylem. In some parts of the stem near the base of the shoot and at the nodes the enzyme may also occur in the medulla and cortex. When galiosinase occurs outside the cambium it may be accompanied by its specific substrates, the glucoside and primveroside of purpurin-3-carboxylic acid. In the parts which accumulate the purpurin-3-carboxylic acid glycosides there is an approximately direct proportionality between the concentrations of enzyme and glycoside. When kept in water for a few days the excised leaves and stems of some species produce large amounts of galiosinase. The formation of enzyme in excised parts is closely followed by the accumulation of purpunn-3-carboxylic acid glycosides. The bearing of these observations on the problem of the physiological role of glycosidases (glycoside synthesis, lignification, &c.) is discussed.

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