GERMINATION SELF-INHIBITORS FROM COLLETOTRICHUM-GLOEOSPORIOIDES F SP JUSSIAEA

Three self-inhibitors of conidial germination were isolated from Colletotrichum gloeosporioides f. sp. jussiaea and identified as (E)- and (Z)-3-ethylidene-1,3-dihydroindol-2-one and (2R)-(3-indolyl) propionic acid. These compounds were named CG-SI (C. gloeosporioides-self-inhibitor) 1, 2 and 3, respectively, The inhibitors reduced the germination of conidia with ED(50) values of 3 mu g/ml for CG-SI 1, 5 mu g/ml for CG-SI 2, and 100 to 150 mu g/ml for CG-SI 3. Among 16 tested species of anthracnose fungi, CG-SI 1, 2, and 3 were only detected from C. gloeosporioides f. sp. jussiaea and C. fragariae. Activity of the self-inhibitors was greater for germination than for germ tube growth and the effects were greatest against the fungal species that produced them. The evidence indicates that CG-SI 1, 2, and 3 are physiologically important as germination self-inhibitors in these fungi.