Sequential release of both basic and acidic isoperoxidases to the media of suspension cultured cells of Capsicum annuum.

The establishment of suspension cell cultures from trimmed cotyledons of pepper (Capsicum annuum L.) provides a new experimental system for studying the relationship between release of peroxidase (EC 1.11.1.7) into the free intercellular spaces and plant cell growth. In contrast with several other species, the total peroxidase activity in the medium increased continuously during the post-exponential growth phase of the pepper cell culture, and this was correlated with the growth inhibition of pepper cells cultivated in suspension. The increase in the peroxidase activity in the culture medium was the consequence of a differential release of isoperoxidases, prominently marked by a primary release of basic isoperoxidases, followed by a strong increase in the level of acidic isoperoxidases. Thus, pepper cells cultures constitute a new experimental system for studying the regulation of the sequential release of basic and acidic isoperoxidases, which occurs during the growth cessation of plant cells.