VACUOLE PROTEINS IN PARENCHYMA CELLS OF SECONDARY PHLOEM AND XYLEM OFDALBERGIA-ODORIFERA

Light- and electron-microscopic observations were made on the stem par enchyma cells of Dalbergia odorifera T. Chen (Papilionaceae), a tropic al deciduous tree. In the secondary phloem of branchlet and trunk, all of the parenchyma cells except companion cells contain vacuole protei ns. Only the outer secondary xylem of branchlets, but not trunk second ary xylem, has proteins in the ray parenchyma and the vasicentric pare nchyma. The xylem vacuole proteins begin to accumulate at the end of t he growing period and they disappear after the first flush of growth i n spring. The vacuole proteins in phloem cells, particularly in the ce lls near the cambium. also show seasonal fluctuations. Under the elect ron microscope, the vacuole proteins appear as fibrous materials in ag gregation or in more or less even dispersion, and they occur in the la rge central vacuoles during both the growth and dormant periods. Accor ding to the published studies, the stem storage proteins in the temper ate trees appear as small protein-storage vacuoles or protein bodies, and the proteins in the tropical trees occur in large central vacuoles . This distinction is assumed to be related to the differences in the nature of dormancy between temperate and tropical trees.