Species: Melandrium yellow fleck virus
Glasshouse Crops Research Institute, Littlehampton, Sussex, BN16 3PU, England
University of Agricultural Sciences, Institute for Plant Protection, H-8361 Keszthely, P.O. Box 71, Hungary
Host Range and Symptomatology
Transmission by Vectors
Transmission through Seed
Transmission by Grafting
Transmission by Dodder
Nucleic Acid Hybridization
Stability in Sap
Properties of Particles
Properties of Infective Nucleic Acid
Relations with Cells and Tissues
Ecology and Control
A virus with RNA-containing isometric particles c. 25 nm diameter, found in Melandrium album in Hungary. The virus is readily sap-transmissible to a wide range of herbaceous plant species. No vector is known.
No species gives diagnostic reactions, but a combination of the following species is useful:
Chenopodium quinoa. Numerous small, necrotic brown local lesions in 3-5 days (Fig.2), enlarging and coalescing to give necrotic areas. No systemic infection.
Cucumis sativus cv. Butchers Disease Resister. Sharply-defined yellowish local lesions in 4-7 days; occasional systemic infection, with chlorotic spots and flecks.
Melandrium album. Local necrotic rings after 5-7 days; systemic vein clearing and yellow flecks.
Nicotiana clevelandii. Chlorotic and necrotic local lesions in 3-5 days, becoming extensive necrotic areas. Systemic severe mottle, blistering, puckering, rosetting and much necrosis (Fig.1).
Phaseolus vulgaris (French bean) cv. The Prince. Numerous small brown necrotic local lesions in 3 days (Fig.3); no systemic infection.
Reactions in other commonly used test plants include:
Chenopodium amaranticolor, C. capitatum, C. murale. Necrotic local lesions (Fig.4). Systemic infection occasionally occurs in C. murale, with leaf dwarfing and chlorosis.
Datura stramonium. Local chlorotic spots and rings in about 1 week; no systemic infection.
Gomphrena globosa. Small, whitish necrotic local lesions in about 1 week; systemic coarse yellowish mottle and stunting.
Lycopersicon esculentum (tomato) cv. Moneymaker. Few chlorotic local lesions in about 1 week; no systemic infection.
Nicotiana glutinosa. Few chlorotic local lesions; no systemic infection.
N. glutinosa x N. clevelandii hybrid. Chlorotic local lesions after about 1 week; systemic bright yellow-green mottle in 2 weeks, with some dwarfing. Subsequent growth with only slight mottle.
N. tabacum (tobacco) White Burley. Chlorotic local lesions in 7-10 days, enlarging to chlorotic rings and ring-spots. No systemic infection.
Petunia hybrida cv. Fire Chief. A few chlorotic local lesions in 5-6 days; no systemic infection.
Pisum sativum (pea) cv. Onward. Systemic severe mottle, leaf distortion and stunting, with spreading necrosis killing the plant.
Tetragonia expansa. White necrotic local lesions after about 6 days; systemic vein yellowing, leaf twisting and malformation.
Tropaeolum majus. Irregular chlorotic local lesions and areas; systemic yellow vein-netting and leaf dwarfing.
N. clevelandii is useful for virus propagation and for maintaining cultures.
Chenopodium quinoa and Phaseolus vulgaris give satisfactory local lesions.
In immunodiffusion, a single line of precipitation is formed (Fig.5), and good reactions were obtained in 0.8% agar or agarose gels in distilled water or in 0.02 M phosphate buffer (Hollings & Horváth, 1978).
Further purification can be achieved by molecular permeation chromatography: apply 1.0-1.5 ml of the partially purified preparations to columns (85 x 1.5 cm) of controlled-pore glass beads (70 nm pore size), and elute the virus with 0.05 M Na-phosphate buffer, pH 7.6. The virus is eluted immediately after the void volume (Barton, 1977; M. Hollings & R. J. Barton, unpublished results). Yields of 200 mg virus/kg leaf can be obtained.
A260/A280: 1.66 to 1.69; Amax(260)/Amin(242): 1.39 to 1.43 (values corrected for light-scattering).
Electrophoretic behaviour: in immunoelectrophoresis in 0.8% Ionagar no. 2 in 0.02 M phosphate buffer pH 7.6 at 2°C, a single antigenic component was present, moving rather rapidly towards the anode (Fig.5) at approx. 9.5 x 10-5 cm2 v-1 sec-1.
Nicotiana clevelandii plants: (left) 7 days after infection, showing irregular necrotic local lesions, and developing systemic leaf mottle and puckering; (right) 20 days after infection, showing very severe stunting, rosetting, puckering, mottle and leaf necrosis.
Chenopodium quinoa: necrotic local lesions 5 days after infection.
Phaseolus vulgaris cv. The Prince: necrotic dot local lesions 11 days after infection.
Chenopodium murale: necrotic local lesions 8 days after infection.
Immunoelectrophoretogram: after 1 h electrophoresis in 0.8% (w/v) Ionagar no. 2 in 0.02 M phosphate buffer (pH 7.6) at 2°C, 4.4 v/cm. The single antigenic component migrates rather rapidly towards the anode.
Partially purified preparation of the virus stained in phosphotungstate (pH 6.5), showing isometric particles and tubular structures. Bar represents 200 nm.