Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Dec;30(4):526-537.
doi: 10.1007/s13337-019-00552-3. Epub 2019 Nov 27.

Distribution and diversity of viruses infecting yams (Dioscorea spp.) in Cameroon

I N Azeteh  1   2 , R Hanna  1   3 , A P Njukeng  2 , A O Oresanya  4 , P N Sakwe  5 , P Lava Kumar  4
Affiliations

Distribution and diversity of viruses infecting yams (Dioscorea spp.) in Cameroon

I N Azeteh et al. Virusdisease. 2019 Dec.

Abstract

Yam (Dioscorea spp.) is an important food crop cultivated for its edible tubers in Cameroon. Surveys were conducted in Cameroon to determine the incidence and severity of yam mosaic disease and associated viruses in 124 yam farms in four agro-ecological zones in 2014 and 2016. Dioscorea rotundata, D. cayenensis, D. alata, D. Dumetorum and D. bulbifera were most frequently detected yam species in the fields. Symptoms of virus disease were observed on 81.5% of the farms surveyed and the disease incidence ranged from 0 to 96.7%, with an overall mean of 26.5%. Mean symptom severity estimated using a numerical rating scale of 1-5, ranged from 2 to 4.1, with an overall mean of 2.6. Representative set of leaf samples collected from farmers' fields were tested for three viruses known to cause yam mosaic disease in West Africa, viz., Yam mosaic virus (YMV), Yam mild mosaic virus (YMMV) and Cucumber mosaic virus (CMV), using multiplex RT-PCR. YMV and YMMV were detected in 220 (37.2%) of the 591 samples tested and 75% of the farms surveyed. None of the samples tested positive to CMV. Phylogenetic analysis based on the coat protein sequencing of 27 YMV isolates clustered these isolates into three phylogenetic groups. This study demonstrated high prevalence of mosaic disease in yam fields and YMV as main causal agent. Knowledge generated in this study will be useful to augment diagnostic tools and yam mosaic disease control with a view to improve on yam production in Cameroon.

Keywords: Sequence diversity; Viral diseases; Virus diagnostics; Yam virus disease surveys.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Percent virus disease incidence in the surveyed yam farms in Cameroon
Fig. 2
Fig. 2
Mean virus disease severity assessed based on 1–5 rating scale in the order of increasing symptom severity in the surveyed yam fields in Cameroon
Fig. 3
Fig. 3
Variety of viral disease symptoms observed on naturally infected yams in farmers’ fields in Cameroon. a Uninfected, b Stunting, mosaic and distortion, c Severe mosaic, d Shoe-stringing with mosaic, e Bleaching, f Leaf distortion, g Green-vein banding, h Mosaic with bleaching, and i Mild mottling
Fig. 4
Fig. 4
Unrooted phylogenetic tree constructed using the maximum-likelihood method with the aid of MEGA 7 software. The phylogenetic tree was constructed using the complete coat protein encoding gene of 27 YMV isolates detected in this study in Cameroon. Bootstrap values (1000 replicates) are shown at the branch nodes and branches corresponding to partitions reproduced in < 50% of bootstrap replicates are collapsed. The three groupings are indicated
Fig. 5
Fig. 5
Rooted phylogenetic tree depicting evolutionary relationships among Yam mosaic virus (YMV) and Yam mild mosaic virus (YMMV) isolates characterized in Cameroon. The phylogenetic tree was constructed using the complete coat protein encoding gene of 27 YMV isolates, 2 YMMV isolates and 16 YMV isolates from NCBI GenBank and the tree was rooted using YMMV as out-group. The tree was constructed using the MEGA7 [20]. Bootstrap values (1000 replicates) are shown at the branch nodes and branches corresponding to partitions reproduced in < 50% of bootstrap replicates are collapsed
See this image and copyright information in PMC

References

    1. Abarshi MM, Mohammed IU, Jeremiah SC, Legg JP, Kumar PL, Hillocks RJ, Maruthi MN. Multiplex RT-PCR assays for the detection of both RNA and DNA viruses infecting cassava and the common occurrence of mixed infections by two cassava streak brown streak viruses in east Africa. J Virol Methods. 2012;179:176–184. doi: 10.1016/j.jviromet.2011.10.020. - DOI - PubMed
    1. Adeniji MO, Shoyinka SA, Ikotun T, Asiedu R, Hughes Jd’A, Odu BO. Yield loss in guinea yam (Dioscorea rotundata Poir.) due to infection by Yam mosaic virus (YMV) genus potyvirus. Ife J Sci. 2012;14(2):237–244.
    1. Aleman-Verdageur ME, Goudou-Urbino C, Dubern J, Beachy RN, Fauquet C. Analysis of the sequence diversity of the P1, HC, P3, Nib, and CP genomic regions of several yam mosaic potyvirus isolates: implications for the intra-species molecular diversity of potyviruses. J Gen Virol. 1997;78:1253–1264. doi: 10.1099/0022-1317-78-6-1253. - DOI - PubMed
    1. Ayisah KD, Gumedzoe YMD. Genetic diversity among Yam mosaic virus (YMV) isolates infecting yam of the complex Dioscorea cayenensis-rotundata in Togo. Int J Biol Chem Sci. 2012;6(3):1090–1101.
    1. Bhattacharjee R, Gedil M, Sartie A, Otoo E, Dumet D, Kikuno H, Kumar PL, Asiedu R. Dioscorea. In: Kole C, editor. Wild crop relatives—genomic and breeding resources, industrial crops. Berlin: Springer; 2011. pp. 71–96.

LinkOut - more resources