PHYSICOCHEMICAL PROPERTIES AND MODE OF ACTION OF INHIBITORS OF PLANT-VIRUS REPLICATION PRESENT IN OPERCULINA-TURPETHUM L AND SCILLA-INDICA BAKER

Extracts from leaves of Operculina turpethum and bulbs of Scilla indic a plants showed broad spectrum virus inhibitory property. Treatment wi th these extracts induced systemic resistance against sunnhemp rosette virus, tobacco mosaic virus, datura shoestring virus and tomato spott ed wilt virus infections in their susceptible plants. The induction of systemic resistance presumably involved the production of some active virus-neutralizing agent (s) (VNA) in treated plants. The VNA was abs ent in nontreated plants. The degree of resistance varied in different host-virus combinations and persisted for more than 12 days in case o f susceptible plants treated with O. turpethum inhibitor, however, it had collapsed after 3 days in plants treated with S. indica inhibitor. Resistance induced in host plants whose lower leaves had been treated with inhibitors was significantly reversed on simultaneous applicatio n of actinomycin-D (20-mu-g/ml). The physicochemical properties reveal ed that inhibitors from O. turpethum and S. indica were active up to a dilution of 1 x 10(-3) and 2 x 10(-2) g/ml, adsorbed on activated cha rcoal and celite, had high thermalstability up to 90-degrees-C and 80- degrees-C prolonged storage in vitro at room temperature (26 +/- 5-deg rees-C), respectively. The inhibitor present in O. turpethum was non-d ialyzable, activately precipitated with ammonium sulphate and ethanol. However, inhibitor from S. indica was dialyzable, inactivated when pr ecipitated with ammonium sulphate and ethanol.On incubation with prote olytic enzymes, the O. turpethum inhibitor lost the activity, S. indic a inhibitor, however, was uneffected.