CHARACTERIZATION OF A VIRUS CAUSING MOSAIC DISEASE IN CUCUMBER (Cucumis sativus L.)
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Date
2012
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Abstract
ABSTRACT
Surveys during 2011-12 revealed the incidence of mosaic disease in cucumber (Cucumis sativus L.) varying from
0-66 per cent in Solan and Sirmour districts of Himachal Pradesh. The characteristic symptoms exhibited by present isolate
both under natural and glass house conditions were vein clearing, vein banding, mild mosaic to yellow mosaic, blistering on
leaves along with stunted growth of vines bearing small sized distorted fruits. Three isolates representing distant locations
were found to be similar as far as their reaction on certain indicator hosts (Nicotiana glutinosa L., N. tabacum var. White
Burley, N. debneyii L., N. occidentalis “37B”, Chenopodium album L., C. amaranticolor Coste and Reyn, C. quinoa Wild,
Datura metel L., and D. metel var. festuasa) and serological identity with potyvirus group specific antibodies is concerned.
An isolate was then further selected for partial characterization. The isolate was easily transmissible through sap as well as
by aphid vectors Myzus persicae and Aphis craccivora and it was not seed and soil transmissible. The host range studies
revealed that the virus isolate could infect Amaranthus caudatus L., Capsicum annuum L. (chilli), Capsicum annuum L. var.
“California Wonder”, Chenopodium album L., Chenopodium amaranticolor Coaste and Reyn., C. quinoa Wild,
Callistephus chinensis L. var. Sushank, Citrullus lanatus (Thunb), Cucurbita pepo L. var. Australian Dark Green, Cururbita
pepo L var. Pusa Alar, C. moschata (Duch.) Poir,Cucumis melo L. var. “Hara Madhu” Cucumis sativus L., Gomphrena
globosa (L.), Datura metel L., Datura metel L. var. festuosa, Lagenaria siceraria (Molina) Standl., Luffa acutangula (L.)
Roxb., Luffa cylindrica Roem., Momordica charantia L., Nicotiana glutinosa L., N. tabacum L. var. “White Burley”, N.
debneyii Dowin., Nicotiana occidentalis “37B”, Phaseolus vulgaris L. var. “Jwala”, Phaseolus vulgaris L.var. Pinto,
Physalis floridana Rydb., Pisum sativum L., Petunia hybrida Vilm, Raphanus sativus L., Vicia faba L., Vigna sinensis Savi,
Zinnia elegans Jacq, species. However, it was not found to infect Abelmoschus esculentus Monech, C. murale L.,
Lycopersicon esculentum Mill var. “Solan Gola”, Solanum nigrum L., Solanum tuberosum L., Solanum melongena L. and
Tagetes erecta L. var. Pusa Narangi plant species. Biophysical properties of the virus isolate included TIP of 65-70°C, DEP
of 10-3-10-4 and LIV of 4 days at room temperature (22-26°C) and 8 days under refrigeration (4+1oC). Serological
identification of virus isolate through DAC and DAS-ELISA showed strong positive serological relationship with WMV-2
antiserum besides a mild reaction with ZYMV antibodies. Morphologically, virus isolate had flexuous rod shaped particles
and ultrathin section studies revealed the presence of scroll inclusions and virus particles in cytoplasm. The present virus
isolate was also successfully detected in RT-PCR assay by using potyvirus group specific primers (CPUP & P9502) and
resulted into a desired product of ~725 bp. Hence, based on the results of identification parameters particularly host range,
transmission, particle morphology, serological relationship and RT-PCR detection, the present virus isolate had been
identified to be similar to WMV-2 belonging to potyvirus genus in family potyviridae. Further studies on molecular
characterization will confirm its exact identity and homology with other WMV-2 reported from different parts of the world.
In screening of eighteen varieties/hybrids and twenty five local collections of cucumber under field conditions revealed that
eight local collections of cucumber were immune to the present virus isolate as no symptoms were observed on these
collections.