Differentiation of Photorespiratory Activity between Mesophyll and Bundle Sheath Cells of C_4 Plants II. Peroxisomes of Panicum miliaceum L.

概要

論文の詳細を見る
Peroxisomes were isolated by sucrose density gradient centrifugation from mesophyll and bundle sheath protoplasts of a C_4 plant, Panicum miliaceum L. The equilibrium density in the gradient was 1.25 for bundle sheath peroxisomes and 1.23 for mesophyll peroxisomes, the former density being similar to that of peroxisomes of wheat mesophyll protoplasts. Photorespiratory and other microbody enzymes were assayed for the peroxisomes of P. miliaceum to detect possible differentiation at an enzyme level. The specific activities of photorespiratory enzymes, except for hydroxypyruvate reductase, in bundle sheath peroxisomes were 40-60% of those in wheat peroxisomes, when compared on a protein basis, and only 20-30% in mesophyll peroxisomes. However, peroxisomes from both cell types contained significant levels of all the enzymes involved in the photorespiratory glycolate pathway, when compared with castor bean glyoxysomes. The activity of hydroxypyruvate reductase in the peroxisomes of P. miliaceum was comparable to or higher than that in wheat peroxisomes. Two p-oxidation enzymes and urate oxidase were detected in the peroxisomes in a similar level to that in wheat peroxisomes. These results suggest that the peroxisomes of mesophyll and bundle sheath cells of P. miliaceum are essentially similar to those of C_3 plants, and that they cannot be differentiated except for a difference in equilibrium density in a sucrose gradient.
日本植物生理学会の論文