Cowpea viruses: Effect of single and mixed infections on symptomatology and virus concentration

Moni A Taiwo,Kehinde T Kareem,Jackies D'A Hughes,Imade Y Nsa

doi:10.1186/1743-422x-4-95

Moni A Taiwo, Kehinde T Kareem + Show 2 more

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https://doi.org/10.1186/1743-422x-4-95

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Abstract

Natural multiple viral infections of cultivated cowpeas have been reported in Nigeria. In this study, three Nigerian commercial cowpea cultivars ("Olo 11", "Oloyin" and "White") and two lines from the IITA (IT86D- 719 and TVU 76) were mechanically inoculated with Cowpea aphid-borne mosaic virus (CABMV), Bean southern mosaic virus (SBMV) and Cowpea mottle virus (CMeV) singly, as well as in all possible combinations at 10, 20 and 30 days after planting (DAP). Samples of leaves or stems were collected at 10, 20 and 30 days after inoculation (DAI) and analyzed for relative virus concentration by Enzyme-Linked Immunosrbent Assay. All the cultivars and lines {CVS/L} were susceptible to the viruses but the commercial CVS showed more severe symptoms and had relatively higher viral concentration. In single virus infections, CABMV which induced the most severe symptoms had absorbance values (at 405 nm) of 0.11 to 0.46 while SBMV and CMeV which induced moderate symptoms had virus titre of 0.74 to 1.99 and 0.11 to 0.90 respectively. Plants inoculated 10 DAP had significantly higher virus concentration than those inoculated 30 DAP. In mixed infections involving CABMV (10 DAP) apical necrosis and death were observed in commercial cultivars "Olo 11" and "White". Enhancement of CMeV titers were observed in plants infected with CMeV + CABMV. Multiple viral infections of cowpeas may result in complete yield loss, hence, the availability of seeds of cultivars with a high level of multiple virus resistance is recommended as a means of control.

Highlights

In Cowpea research, production and utilization Edited by: Singh SR, Rachie KO
Some of the cultivars ("Olo 11", "White", TVU 76) that were inoculated with a mixture of two viruses (CABMV+SBMV or Cowpea aphid-borne mosaic virus (CABMV)+Cowpea mottle virus (CMeV)) at 10 days after planting (DAP) died prematurely while the other CV/L were stunted with completely reduced leaf size (Table 1)
The results of this study have shown that the three Nigerian commercial cultivars (Olo 11, White, Oloyin) used in this investigation are susceptible to CABMV, CMeV and SBMV

Summary

Introduction

In Cowpea research, production and utilization Edited by: Singh SR, Rachie KO. Viruses infecting legumes in Nigeria: case history. Proceedings of a conference organized by IITA, Ibadan, Nigeria; 2003:93-115. 3. Thottappilly G, Rossel HW: Virus diseases of cowpea in tropical Africa. Estimated yield losses due to viral infection of cowpeas are between 10% and 100% [1]. Cowpea lines with individual and combined resistance to several cowpea viruses have been identified at the International Institute of Tropical Agriculture (IITA) and tested for local adaptation [3]. Viruses are still detected on commercially cultivated cowpeas in Nigeria [4]. Shoyinka et al, [5] reported that there was no ecological restriction to the distribution of the six viruses detected. Cowpea aphid-borne mosaic virus (CABMV) genus Potyvirus and Bean southern mosaic virus (SBMV) genus Sobemovirus were highly prevalent but had moderate incidence while Cowpea mottle virus (CMeV) genus Carmovirus was moderate in both incidence and prevalence

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