Ultrastructural Studies on the Ca2+ Localization in the Dividing Cells of the Maize Root Tip.

Abstract

ABSTRACT. The distribution of Ca2+ in dividing cells of the maize root tip was examined by potassium pyroantimonate precipitation and EGTA treatment methods. Ca2+ was found in most of the cell organelles, such as the matrix of the mitochondria, the thylakoid membrane of the proplastid and the Golgi vesicles, and on the plasma membrane. Ca2+ was also distributed throughout the cytoplasmic ground matrix and attractoplasm, inside the vacuoles, in the granular zone of the nucleolus in the interphasic nucleus and in the regenerated nucleolus in the telophasic nucleus. The amounts of Ca2+ distributed in the cytoplasmic ground matrix, the vacuole and the nucleolus varied during nuclear division. From the results of the present experiment, the following considerations on the role of Ca2+ and the regulation site of Ca2+ in dividing plant cells were drawn: 1) Ca2+ may play a role in the construction of the granular form of the ribosome. 2) Ca2+ may be an essential ion in the regeneration of nucleolus. 3) Vacuoles may act as the regulatory site of the Ca2+ concentration in the cytoplasm and attractoplasm in plant cells. Spindle microtubules and phragmo-microtubules are probably surrounded by other ions, such as Mg2+.

Calcium distribution and function in the glandular trichomes of Lavandula pinnata L

“…In its ionic form (Ca 2+ ) it has been shown to be crucial in the control of numerous physiological and developmental processes in plants (Bush 1995, Zhang and Cass 1997, Trewavas and Malhó 1998, Sanders et al 1999, Scrase-Field and Knight 2003, Medvedev 2005, Wheeler and Brownlee 2008. For instance, the Ca 2+ ion is involved in intracellular events such as protoplasmic streaming, nuclear division, cell division, cell plate formation, and polarized growth in rhizoids and pollen tubes (Takagi and Nagai 1983, Sakai-Wada and Yagi 1993, Malhó and Trewavas 1996, Taylor and Hepler 1997, Franklin-Tong 1999, Eckardt 2001, Plieth 2001, Campanoni and Blatt 2007. Removal of calcium from the nutrient supply results in rapid death of cells in the apical meristem, and a cessation of growth (Epstein 1972, Gilroy et al 1993.…”

“…Calcium has also been implicated in the function of the stylar transmitting tract (Zhao et al 2004), dividing root cells (Vaughan et al 1987, Sakai-Wada andYagi 1993) and potentially as a causative factor in Blossom-end rot of tomato (Suzuki et al 2003). Despite what is known from these studies, a role for calcium in the secretion of essential oils has not been established.…”