Regulation of callose synthase activity in situ in alamethicin-permeabilized Arabidopsis and tobacco suspension cells.

Background: The cell wall component callose is mainly synthesized at certain developmental stages and after wounding or pathogen attack. Callose synthases are membrane-bound enzymes that have been relatively well characterized in vitro using isolated membrane fractions or purified enzyme. However, little is known about their functional properties in situ, under conditions when the cell wall is intact.