Cell Biology international Reports, Vol. 11, No. 3, March 1987 157 TCCALIZATION OF Ca++ t , IONS AND PERCXIDASE ACTIVITY IN TKE ZONE OF C.AT,T,OSE WALL SYNTHESIS IN DYADS AND TETRPDS OF TJARIX DECTDUA MILL. A. Tretyn, E. Bednarska and A. Gorska-Brylass Department of Plant Cytology and Genetics, Institute of Biology, Copernicus University, 8'7-TOO Torufi, Poland AB3TJRRCT The localization of Ca++ ions and peroxidase activity were studied cytochemically during succesive phases of callose synthesis in the cells of dyads and tetrads of Larix decidua. It has been found that at the time prece-, ding the formation of callose wall separating the dyad and tetrad cells there occurs an ipgrease in peroxidase activity and an accumulation of Ca ions in zone of ca'.- lose wall formation. These results suggest a physiolo- gical part of these factors in callose synthesis. Key words: Ca++, callose synthesis, T,arix decidua Mill.., microsporogenesis, peroxi.dase activity. TNTRCDUCTI0N Studies carried out in our laboratory on peroxidase activity in microsporogenesis of larch have that the highest activity level of this enzyme occurs in stages immeditely preceding callose synthesis, i.e, in the young dyads and tetrads (Gorska-Bcylass et al 1981). Cytochemical studies on intracellular localization of peroxidase have confirmed the relationship of this enzy- me with callose synthesis, since it has been found that in the dyads and tetrads of larch and other coniferes the product of enzymatic reaction selectivel:y accumula- ted in the callose synthesis zone (%5bel. and Gorska- Brylass in preparation). Further studies on different types of cells synthesizing callose have demonstrated 0309-1651/871030157-081$03.00/0 @ 1987 Academic Press inc. (London) Ltd.