THE RESISTANCE OF COWPEA SEEDS TO BRUCHID BEETLES IS NOT RELATED TO LEVELS OF CYSTEINE PROTEINASE-INHIBITORS

A cDNA encoding a cysteine proteinase inhibitor was isolated from a cD NA library prepared from developing seeds of an insect-resistant line of cowpea. The sequence of the encoded protein was homologous with tho se of other plant cysteine endoproteinase inhibitors, and with Type 2 cystatins from animals. Southern blot analyses indicated that small ge ne families were present in both resistant and susceptible lines of co wpea, while northern blot analyses showed similar levels of expression . It is concluded that the levels of expression of the inhibitor do no t account for the differences in insect resistance of the two lines.