Purified chestnut cystatin inhibited the growth of the phytopathogenic fung
i Botrytis cinerea, Colletotrichum graminicola, and Septoria nodorum, but n
ot that of the saprophyte Trichoderma viride. Furthermore, the cystatin str
ongly affected the protease activity of B. cinerea but had no effect on the
protease activity of T. viride. These results suggest that chestnut cystat
in contributes to plant defense against phytopathogenic fungi.