Ultracytochemical localization of Ca2+ during the phloem ganglion development in Phyllostachys edulis

Abstract

Ultracytochemical localization of Ca²⁺ was investigated using the potassium pyroantimonate precipitation method during the development of phloem ganglion. The result showed that Ca²⁺ was mainly localized in the cell wall and intercellular spaces in the initiating phase. With the development of the phloem ganglion, the distribution of Ca²⁺ transferred to the vacuole, and the Ca²⁺ deposits in the cell wall and intercellular space decreased. At the later stage of the developmental phase, Ca²⁺ was distributed in the tonoplast and vacuole phagocytosis, and the vacuole became the main calcium storage in this phase. At the early stage of maturation of the phloem ganglion, most of the phloem ganglion cells  vacuoles cracked, and the cytoplastic Ca²⁺ content increased in large number. In the mature phloem ganglion, not only were there a few Ca²⁺ localized in the cytoplast of mature cells, but also in the differentiating cells in the vacuoles. Ca²⁺ was distributed in the tonoplast and vacuole contents; initiating cells almost had no Ca²⁺. In general, Ca²⁺ concentration in mature phloem ganglion cells was at a low level. The results indicated that the changes in Ca²⁺ distribution evoked the phloem ganglion generation, and Ca²⁺ regulated the physiological function of the phloem ganglion.