Further characterization of celery latent virus

Abstract

Celery latent virus has been isolated from plants of celeriac (Apium graveolens var.rapaceum).Chenopodium amaranticolor andC. quinoa are good assay plants. Celery (A. graveolens var.dulce) and celeriac (13 cultivars tested) did not react with visible symptoms. Fourteen new artificial hosts were found. New systemic symptomless hosts areAnthriscus cerefolium, Nicotiana megalosiphon, Pisum sativum, Spinacia oleracea andTrifolium incarnatum. Systemic symptoms were caused in the pea cultivars Cicero and Dark Skin Perfection. Five aphid species, includingCavariella aegopodii, four of which not tested with the virus before, were unable to transmit the virus. Seed transmission was confirmed in celeriac (up to 34%) and inC. quinoa (up to 67%) and detected for the first time inAmaranthus caudatus. Detection is easier in seedlings and germinated seeds than in dry seeds. Results of purification were erratic but best at high pH (8 or 9). Sedimentation coefficient was 161 S. An antiserum reacted with purified virus in micro-precipitin tests (titer 256) but, especially at high salt concentrations also in agar gel (titer 64), presumably because of easy degradation of virus protein. Reactions in agar gel also occurred with crude extracts from virus-infectedC. quinoa and celeriac. With the electron microscope flexuous virus particles were found in low concentration in crude sap and in high concentration in purified preparations. Particle measurements revealed an average length of 885 nm (in one preparation 940 nm). Light microscopy did not show inclusion bodies in epidermal strips nor did electron microscopy of ultrathin sections reveal pinwheels and other structures typical of the potyvirus group. The virus evidently belongs to a new morphological group, possibly together with some other viruses hitherto insufficiently studied. The virus seems of potential economic importance only, but it is advised to use virus-free mother plants of celery for seed production.