Abstract
In other to find an alternative hosts of virus diseases of cowpea in Zaria area, two virus disease symptoms were observed on two wild plants growing near each other at the edge of an experimental field, Department of Biological Sciences, Ahmadu Bello University, Zaria. The virus isolate in Talinum triangulare was found not to be sap transmissible in all the buffers used at different molarities and pH values; although the virus was found to be seed transmissible in T. triangulare, and also transmissible through grafting to healthy looking seedlings of Vigna unguiculata var. IAR-01-1006. Also symptoms were not observed in whiteflies (Bemisia tabaci) inoculated seedlings of the test plants. The virus isolate in Desmodium tortuosum, however, was found to be sap transmissible to healthy looking seedlings of D. Tortuosum and a number of other plant diseases, especially members of Fabaceae family. Chlorotic local lesions were observed in Chenopodium amaranticolor. 0.1 M phosphate buffer, pH 7.4 was found to be suitable for isolation and purification of the virus in D. tortuosum. The present study has also shed some light on the possible propagation host (V. unguiculata var. IAR-01-1006) for T. triangulare virus isolate, a propagation and assay hosts (V. unguiculata var. IAR-01-1009 and C. amaranticolor) for D. tortuosum virus isolate. The results obtained suggested that the symptoms observed in the two wild plants were induced by two different virus isolates. It is, therefore, suggested that further studies like molecular and immunological techniques need to be carried out in order to explore more of the properties of these viruses, with the view to develop control measures; since the viruses have shown to be a potential threat to some of the most important Leguminosae crops in the area studied.
Highlights
Viruses have been variously defined as any of the large group of submicroscopic infective agents that are regarded either as extremely simple microorganisms, or as extremely complex molecules, that typically contain a protein coat surrounding an RNA or DNA core of genetic materials, but no semi-permeable membrane
Puttaraju et al [3] reported that number of pods per plant; number of seeds per pod and 100-seed weight was significantly reduced in plants infected by Bean Common Mosaic Virus (BCMV)
The symptom was transmissible through seeds in T. triangulare, because out of the 250 seedlings raised from the infected plants, 140 (56%) showed symptoms similar to what was observed on the original plant
Summary
Viruses have been variously defined as any of the large group of submicroscopic infective agents that are regarded either as extremely simple microorganisms, or as extremely complex molecules, that typically contain a protein coat surrounding an RNA or DNA core of genetic materials, but no semi-permeable membrane. They are capable of growth and multiplication only in living cells, and they cause various important diseases in man, lower animals and plants [1]. According to Ittah [5], the relationship between disease severity and yield showed that as disease severity increased, cowpea yield decreased
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