Lettuce big‐vein virus: mechanical transmission and relationships to tobacco stunt virus

Abstract

Big-vein diseased lettuce plants contained an agent that could consistently be transmitted mechanically to Chenopodium quinoa, in which it caused characteristic local lesions. Mechanical transmission was also possible to five other plant species including Nicotiana benthamiana, N. clevelandii and N. occidentalis, but not to lettuce. Symptoms in N. occidentalis were reminiscent of those of tobacco stunt disease. With zoospores of originally virus-free Olpidium brassicae, subcultured on the roots of N. occidentalis-P1, sap-inoculated either from lettuce or via C. quinoa, the agent could be transferred back to lettuce .in which characteristic symptoms of big-vein were reproduced.Infectivity in sap at room temperature was reduced by half after 2 h, and was practically lost after one day. Thermal inactivation was considerable at 45°C and complete at 50°C. Most infectivity was lost at dilution 1:5, and the dilution endpoint was 1:lO. The agent survived well in leaf material stored at -8O"C, or in sap from leaves ground in buffer with DIECA and activated charcoal and freezedried. Mechanical transmission required low dilution (1:2) in the buffer with charcoal, and chilling of materials and utensils.In lettuce, N. occidentalis-Pl and C. quinoa, with all isolates tested but one, infection was always associated with the presence of rod-shaped particles which in the literature have been associated with lettuce big-vein, and are similar to those described for tobacco stunt. Results obtained corroborate the assumption that these particles are the virions of lettuce big-vein virus. The virus also resembles tobacco stunt virus in mechanical transmissibility, instability in sap and symptoms on N. occidentalis.

Lettuce ring necrosis, caused by a chytrid-borne agent distinct from lettuce big-vein ‘virus’

“…The latter most likely is a virus closely related to, but different from , the, as yet taxonomically ungrouped, tobacco stunt virus (TStV; Kuwata and Kubo, 1986) which has rod-shaped particles (Kuwata and Kubo, 1981). Such particles were also frequently but inconsistently found in plants with LBV (Kuwata et al, 1983;Kuwata and Kubo, 1984;Vetten et al, 1987;Huijberts et al, 1990). Our frequent endeavours to see such particles in plants with LRN have also failed, and this agrees with tentative experiences by Verhoyen et al (1985).…”

“…Earlier promising results obtained with TStV and LBV 'virus' (Masri and Hiruki, 1983;Kubo, 1984, 1986;Vetten et al, 1987;Huijberts et al, 1990) have not had any follow-up. Our results with LRN obtained during many years of observation agree with and extend those obtained in Belgium (Verhoyen et al, 1985) and in southern France (H. Lot, pers.…”

“…(1985) pointed to a possible difference between the agents of LRN and LBV, but their attempts to mechanically transmit and purify the LRN agent failed. Parallel and further to our earlier studies Bos and Huijberts, 1990) and those of Vetten et al (1987) on LBV, we also tried to identify the cause of LRN and to study its possible relationships with LBV 'virus' (LBVV), which had been found related to, but different from, tobacco stunt virus (TStV) described in Japan (Vetten et al, 1987;Huijberts et al, 1990). Although associated with virus-like particles, the very labile agents of LBV and of the possibly related freesia leaf necrosis (Bouwen, 1994) remain shrouded in mystery.…”

Nucleotide sequence of the coat protein gene of Mirafiori lettuce virus

“…A rod-shaped particle of Lettuce big-vein virus (LBVV), first reported in Japan, was shown to be associated with the big-vein disease (Kuwata et al 1983). The association of LBVV with big-vein disease was confirmed in Germany and Holland (Huijberts et al 1990;Vetten et al 1987), and LBVV was assumed to cause the disease. The rod-shaped particles were about 320-350 ϫ 18 nm, with a coat protein (CP) of 48 kDa (Huijberts et al 1990;Kuwata et al 1983;Vetten et al 1987).…”

“…Lettuce big-vein disease, first reported in the United States (Jagger and Chandler 1934) The nucleotide sequence determined in this work appears in the DDBJ/EMBL/GenBank nucleotide sequence databases with the accession number AF532872 producing areas (Lactuca sativa L.) in the world and has become an important problem especially during the cooler periods of the year (Campbell 1996;Huijberts et al 1990; Kuwata et al 1983;Vetten et al 1987). The main symptoms are vein bandings in the leaves of affected lettuce plants, with leaf distortion and ruffling.…”