Journal of Plant Pathology Archive

Abstract:

Recent surveys of potato (Solanum tuberosum) fields in northwestern India showed plants with yellow mosaic or flecking symptoms. Symptoms initially appeared as marginal foliar yellowing or chlorotic spots but later the whole leaf blade lamina turned yellow. To test the association of prevalent potato viruses such as Potato virus X (PVX), Potato virus Y (PVYO/C and PVYN), Potato virus A (PVA), Potato virus S (PVS), Potato virus M (PVM) and Cucumber mosaic virus (CMV) in symptomatic plants, double antibody sandwich-ELISA (DAS-ELISA) was performed using commercial polyclonal antisera (Agdia, USA). Testing of twenty samples revealed infection with PVX and CMV subgroup I. To confirm the occurrence of PVX and CMV, total RNA was extracted from symptomatic potato leaves using specific CMV (de Blas et al., 1994) and potexvirus (van der Vlugt and Berendsen, 2002) primers. The expected amplicons of ca. 800 bp for 21PVX and ca. 540 bp for CMV were cloned and sequenced. PVX (GenBank accession No. KJ787641) and CMV (KJ620411) isolates Pot Ldh shared 92.5-97.1% and 91.5-93.4% nucleotide sequence identities with published sequences of PVX (AB056719, M72416 and AJ489260) and CMV Ib (JN054635, KJ874250 and AB046951) from India and other parts of world, respectively. This is the first report of mixed infection of potatoes by CMV and PVX in India. As the symptoms are similar to those caused by Potato aucuba mosaic virus (PAMV) (Loebenstein, 2001) accurate diagnosis of yellow mosaic disease will need to rely on serological or molecular assays.