Analysis of secreted protease inhibitors after water stress in potato tubers.

Potato tubers (Solanum tuberosum) secrete two kinds of proteinase inhibitors after a water stress. The polypeptides have differing inhibitory activities but are Kunitz-type inhibitors based on amino-terminal sequences homologies. A proteolysis maturation type of a cell protease inhibitor was observed. They can constitute high MW complex, sometimes with another type of protein. The function of these protease inhibitors is discussed in relation to plant defence.