Cowpea Stunt: A Disease Caused by a Synergistic Interaction of Two Viruses

Abstract

Severely stunted cowpea plants have been found in similar to those observed on field plants. When inoculated Georgia fields in each of the last 4 yr, 1974 to 1977. Leaves of singly, each virus caused a relatively mild disease; leaves had the stunted plants were small, mottled, blistered, and a mild mottle, and plants displayed moderate stunting during malformed. The causal agent was sap-transmitted to the early infection period and almost no stunting at cowpeas. Several other hosts were susceptible and back senescence. In a greenhouse study, CMV reduced yield of inoculation from Cucumis sativus and Cassia obtusifolia to California Blackeye seed by 14.2% and BICMV by 2.5%. cowpeas established the presence of two viruses: cucumber Yield on doubly infected plants, however, was reduced mosaic virus (CMV) from C. sativus and a potyvirus, later 86.4%. Furthermore, the double infection reduced leaf identified as blackeye cowpea mosaic virus (BICMV), from weight, stem weight, and root weight by 94.3, 89.3, and C. obtusifolia. When seedlings of California Blackeye 87.3%, respectively. Seed and aphid transmission studies cowpeas were inoculated simultaneously with CMV and showed that the viruses can be transmitted from doubly-BICMV, a strong synergistic reaction occurred; the primary infected plants to cause single or double infections in and first two trifoliolate leaves became necrotic within 5-10 cowpeas. The name cowpea stunt is proposed for the disease days and usually abscised. Subsequent leaves were severely caused by the synergistic interaction of CMV and BICMV. diseased but free of the necrosis; the symptoms then appeared

Serological Screening of Cowpea Genotypes for Resistance against Cowpea Aphid Borne Mosaic Virus Using DAS-ELISA

“…Under field conditions, mixed infections with more than one virus have been observed in cowpea (Pio-Ribeiro et al, 1978;Lima et al, 2005). As a result, selection of cowpea cultivars with multiple resistances is fundamental to control mixed infections (Anderson et al, 1996).…”

Simple and multiple resistances to viruses in cowpea genotypes

“…Besides infections caused by isolated viruses, mixed infections with more than one virus have been observed with relative frequency in cowpea under field conditions (Pio-Ribeiro et al, 1978;Lima et al, 2005b). Dwarfing of cowpea caused by a synergistic infection of Blackeye cowpea mosaic virus (BlCMV), of the genus Potyvirus, with CMV was considered a devastating disease in Georgia, Alabama and South Carolina (Pio-Ribeiro et al, 1978).…”

Plant viral synergism: the potyviral genome encodes a broad-range pathogenicity enhancer that transactivates replication of heterologous viruses.

“…This region of the potyviral genome includes the viral genomic 5' untranslated region (UTR) as well as the coding region for the N-terminal portion of the viral polyprotein, including P1, the helper component proteinase (HC-Pro), and approximately one-quarter of P3 (termed P1/HC-Pro sequence). Here, we report that expression of the TEV P1/ HC-Pro sequence also enhances the pathogenicity and accumulation of both tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV), two unrelated plant viruses that cause synergistic disease in conjunction with a potyvirus (Pio-Ribeiro et al, 1978;Clark et al, 1980;Poolpol and Inouye, 1986). We show that in protoplasts, the potyviral sequence prolongs both the accumulation of PVX (-) strand RNA and the expression of a reporter gene from a PVX subgenomic promoter, suggesting that it acts, at least in part, by transactivation of viral RNA replication.…”