Purification and properties of growth stage-dependent antiviral proteins from the leaves of Celosia cristata

Two antiviral glycoproteins, active against mechanical transmission of two tobamoviruses, tobacco mosaic virus and sunnhemp rosette virus, and citrus ring spot virus (ungrouped), were purified from the dried leaves of Celosia cristata. These proteins, called CCP-25 and CCP-27, have M(r)25 and 27 kDa , respectively. Their concentration was found to vary between the pre-flowe ring and post-flowering stages of C. cristata. Either of these proteins, ob tained at different growth stages, inhibited by > 90% lesion formation at a concentration of 20-30 mu g ml(-1). They were resistant to proteases in th e native state, but were readily digested when denatured. Both of them impa rted actinomycin D sensitive resistance by inhibiting local lesions on Nico tiana tabacum cv. Samsun NN by tobacco mosaic virus. Their application, ind ividually, also resulted in high resistance in systemic hosts to sunnhemp r osette virus, and citrus ring spot virus, respectively. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.