Indian Phytopath. aZYXWVUTSRQPONMLKJIHGFEDCBA 52 (2) : 114-117 (1999) A strain of cucumber mosaic cucumovirus causing mosaic in marigold in India DOOMAR SINGH, Q.A. NAQVI and J.D. GARG* Department of Botany, Aligarh M uslim University, Aligarh 202 002 ABSTRACT : A strain of cucumber mosaic cucumovirus causing marigold mosaic was partially characterized. The virus was isolated from diseased marigold (Tagetes erecta L.) plant growing at and around Aligarh. Diseased plants showed mosaic, mottling and stunting. Infected leaf tissue under electron microscope showed the presence of isometric virus particles measuring about 29 nm in diameter, resembling those of cucumoviruses. There was enhanced trapping and decoration of virions with antisera to strains of cucumber mosaic cucumovirus, namely, soybean stunt (CMV-SS) and pea strain (CMV-P) in immunoelectron microscopic studies. There. was niether enhancement of trapping nor any perceptible decoration of virions with antiserum to CMV-KS cucumovirus. Host range, biophysical properties and non- persistent transmission through Aphis gossypii, A. craccivora and Myzus persicae also supported the diagnosis of the virus as a strain of cucumber mosaic cucumovirus. Key words : Marigold mosaic, cucumovirus, purification, !EM Marigold (Tagetes erecta L.) is an important or- namental plant grown in homes, gardens and fields in whole of north and some other parts of India. It is economically important for its showy flowers, tagetes oil and anti-nematicidal properties. It is a host to a few plant viruses some of which cause mosaic disease (Hanson et al., 1951; Joshi and Dubey, 1972; Usman et aI., 1972; Sang and Varma, 1975; Naqvi et al., 1981; Rahman and Rao, 1992), tomato leaf curl virus (Sastry, 1984) and potato yellow dwarf virus (Lockhart, 1989). Symptoms of marigold mosaic disease occurring at Aligarh comprised mosaic and mottling in the be- ginning followed by distortion of leaves leading to bare midribs in the later stages. Due to the great eco- nomic significance of marigold in India and incom- plete characterization of the mosaic causing virus(es), attempts were made to identify and characterize the virus causing mosaic at Aligarh. MATERIALS AND METHODS Leaves of naturally infected plants of Tagetes erecta showing mosaic mottling and stunting were used for aphid and sap inoculation studies. Pure virus cul- ture was maintained on Nicotiana glutinosa while vi- rus was propagated on Nicotiana tabacum var. CTRI *Division of Plant Pathology, Central Potato Research Insti- tute, Shimla 171 001. special type FCV, N. tabacum var. Harison Special and N. rustica. Different plant species used to study the host range of the virus were grown in an insect proof glasshouse in sterilized soil in pots. Chenopo- dium amaranticolar, a good indicator host, produced chlorotic local lesions and was used to check suscep- tibility of other inoculated plant species through back inoculation. Vector transmission was studied by employing aphid species, namely, Aphis gossypii Glov., A. craccivora Koch. and Myzus persicae Sulz. and white- fly, Bamisia tabaci Genn. Aphids and whiteflies used for transmission were starved for 2h, then given ac- quisition feeding of 2 min to 12 h on diseased plants of N . .glutinosa followed by inoculation feeding on healthy plants for 2 min to 24 h. The seeds from infected Tagetes erecta L. and Nicotiana rustica were collected and sown in auto- c1aved soil to study seed transmission. After seedling emergence, the plants were observed till 5-6 weeks and sprayed with 0.02% cypermethrine, an insecticide to prevent insect infestation. Leaf tissues of these plants were also assayed on C. amaranticolor. Electron microscopic studies were carried out by using clarified virus concentrate prepared according to Christie et al. (1987). Since virus particles were ob- served only in the preparation made by using 0.05M phosphate buffer, only this concentration was used for immunoelectronmicroscopic (IEM) studies. Antisera