Phytopath, 2., 75, 82—85 (1972)© 1972 Verlag Paul Parey, Berlin und Hamburg

Kurze Mitteilungen

Division of Mycology and Plant Pathology,Indian Agricultural Research Institute, New Delhi-H, India

Pigweed Mosaic Virus

BySHAMSHER SINGH, ANUPAM VARMA, V. V. CHENULU and V. S. VERMA

^ith 2 figures

Received March 7, 1972

Pigweed {Amaranthus spp.) is susceptible to many plant viruses (BRUNT1968, GRELA 1966, THORNBERRY 1966) but very little attention has been paid totheirnatural infection by viruses. For last three years (1969 to 1971) during theperiod of March to July more than 50% Amaranthus viridis plants aroundDelhi were severely affected with a virus disease. The disease was similar to thatdescribed by PHATAK (1965), The symptoms start as mild chlorotic interveinalpatdies gradually increasing along the veins and finally developing mosaic ofdark green and chlorotic areas (fig. 1). Here an attempt has been made tocharacterize the virus isolated from sudi diseased plants.

The virus was maintained by sap inoculation on A. viridis. For determiningthe host range 45 plant species belonging to 13 families were sap-inoculated.Only Amaranthus species viz. A. blitum, A. caudatus, A. cruentus, A. dubius,A. gangeticus. A. leucarpus, A. mangostanus, A. spinosus, A. viridis were in-fected. Symptoms on all these species were similar to those of the original host.

The virus failed to infect the following plant species: Achyranthes aspera.Beta vulgaris, Bidens pilosa, Blumea lacera, Brassica campestris, B. oleracea,Calotropis procera. Capsicum annuum, Chenopodium album, C. amaranticoior,Crotolaria juncea, Cucurbita pepo, Cyamopsis tetragonoloba. Datura stramo-nium, D. metel, Digera arvensis, Dolichos lablab, Euphorbia hirta, Gomphrenaglobosa, Helianthus annuus, Lufja acutangula, Lycopersicon esculentum, Nico-tiana glutinosa, N. rustica, N. tabacum cv. White Burley, Ocimum sanctum,Phaseolus vulgaris, Phyllanthus niruri, Pisum sativum, Solanum melongena,Sonchus arvensis, Spinacea oleracea, Tropaeolum majus, Vernonia indica, Vignasinensis, Vinca rosea, Xanthium strumarium, Zinnia elegans.

Aphis craccivora, A. gossypii and Myzus persicae successfully transmittedthe virus non-persistently from A. viridis to A. viridis. Even a single aphid.

Pigweed Mosaic Virus 83

A. craccivora could transmit the disease but the symptoms appeared early on testplants which received ten or more aphids. A. nerii, A. rumicis, Macrosiphoniellasonbornii, Rhopalosiphum maidis and Sitobion rosaeformis failed to transmitthe virus. The virus is not carried by seeds.

Fig. 1. Diseased leaves oi Amaranthus viridisFig. 2. Electron micrograph of Pigweed mosaic virus; X 30,500

84 SINGH, VARMA. CHENULU and VERMA

The virus was inactivated by 10 minutes exposure at 60 °C but not at55 °C. It withstood a dilution of 1 : IOO and remained active for 9 days at roomtemperature (15—32 "̂ C) and 16 days at 4 "C in the sap.

The virus was examined in the electron microscope by mounting directlyfrom the infected leaves by the method described by GIBBS, VARMA and WOODS(1966) and shadowing them with gold palladium. Several preparations frominfected leaves revealed that the virus has flexuous long particles. The length ofthe particles varied from 625—775 nm, but the most common length was 700 to725 nm and all the particles were 14 nm wide (fig. 2).

The virus reported here resembles the viruses described by PHATAK (1965)in host range and symptoms. As PHATAK (1965) did not study properties furthercomparison is not possible. The present virus, however, is distinct from the onedescribed by GOVINDASWAMY et al. (1967) in host range and insect transmission.The latter infects Gomphrena globosa, Nicotiana tabacum and N. glutinosa, inaddition to Amaranthus spp. and was not transmitted by A. craccivora, A. gossy-pii and M. persicae.

The virus described here resembles in morphology, physical properties andtransmission with the viruses of the 10th group of BRANDES and WETTER'S (1959)classification of filamentous viruses. There is no other virus of this grouprestricted to the genus Amaranthus only.

The present virus may be the same as described by PHATAK (1965) but inthe absence of complete information it is proposed to consider this as a newvirus and to avoid confusion with the Amaranthus mosaic virus of GOVINDAS-

et al. (1967) it is named 'Pigweed mosaic virus'.

Summary

Pigweed mosaic virus (*/* : */* : E/E : S/Ap) is transmitted by Aphis crac-civora, A. gossypii and Myzus persicae non-persistently; host-range restricted tothe genus Amaranthus; inactivated by heating at 60 ""C and by storage at roomtemperature (15—32°C) in 9 days and 4°C in 16 days. It has long flexuousparticles of 700—725 nm long and 14 nm wide. It resembles the viruses of the10th group of BRANDES and WETTER'S classification of elongated plant viruses.

Zusammenfassung

^Pigweed Mosaic Virus"

Das npigweed mosaic virus" (*/*:*/*: E/E: S/Ap) wird durch Aphiscraccivora, A. gossypii und Myzus persicae nichtpersistent ubertragen; seinWirtspflanzenkreis ist auf die Gattung Amaranthus besdirankt; es wird inakti-viert durch Erhitzen bei 60 °C, durdi Lagerung bei Zimmertemperatur (15 bis32 °C) in neun Tagen und bei 4 °C in 16 Tagen. Es hat fadige, gewundene Par-

Pigweed Mosaic Virus 85

tikeln von 700 bis 725 nm Lange und 14 nm Dicke. Es ahnelt den Viren derzehnten Gruppe der Klassifizierung gestreckter Pflanzenviren von BRANDES undWETTER.

The authors are grateful to Dr. S. P. RAYCHAUDHURI, Head, Division of Mycology andPlant Pathology, I.A.R.I., New Delhi, for providing necessary facilities and encouragementand Dr. NAM PBAXASH, Agricultural Physics Division of this Institute for electron microscopy.

Literature

BRANDES, F . C , and C. WETTER, 1959: Classification of elongated plant viruses on the basisof particle morphology. Virology 8, 99—115.

BRUNT, A. A., 1968: Some hosts and properties of bulbous Iris mosaic virus. Ann. appl. Biol.61.187—194.

GIBBS, A. J.. A. VARMA and R. D. Woous, 1966; Viruses occurring in white clover (Trifoliumrepens L.) from permanent pastures in Britain. Ann. appl. Biol. 58, 35—36.

GoviNDASWAMY, C. V., V. MARIAPPAN, T. K. KANDASWAMY, and C. PADMANABHAN, 1967:Mosaic disease of Amaranthus in Coimbatore (Madras State). Madras agric. J. 54,35—36.

'^GRELA, T., 1966: Investigations on sugarbeet yellows virus. Pr. nauk. Inst. Ochr. Rowl. 8,5—78.

PHATAK, H . C , 1965: Mosaic disease of Amaranthus — A new record for India. Current Sci.34,645—646.

THORNBERRY, H . H. , 1966: Index of Plant virus diseases. Agric. Handbook No. 307, U.S. Dept.Agric, Washington, D.C.

Authors' address: Division of Mycology and Plant Pathology, Indian Agricultural Re-search Institute, New Delhi-12 (India),

"• Original not seen.