Date Published: April 01, 2018
Author(s): Gonçalo Silva, Joshua Oyekanmi, Chukwuemeka K. Nkere, Moritz Bömer, P. Lava Kumar, Susan E. Seal.
Potyviruses (genus Potyvirus; family Potyviridae) are widely distributed and represent one of the most economically important genera of plant viruses. Therefore, their accurate detection is a key factor in developing efficient control strategies. However, this can sometimes be problematic particularly in plant species containing high amounts of polysaccharides and polyphenols such as yam (Dioscorea spp.). Here, we report the development of a reliable, rapid and cost-effective detection method for the two most important potyviruses infecting yam based on reverse transcription-recombinase polymerase amplification (RT-RPA).
Plant pests and pathogens have an important role in global food crops causing significant economic losses in the agricultural industry and threatening food security [, , ]. Yam (Dioscorea spp.) is one of the most important staple food crops worldwide and plays a major role in food security and income generation for more than 60 million people in West Africa, with this region contributing over 95% of the world’s total yam production [4,5]. Yams are generally propagated vegetatively through their tubers, which facilitates the spread and accumulation of pathogens, particularly viruses . To date, several virus species belonging to different genera (Potyvirus, Badnavirus, Cucumovirus, Aureusvirus, Potexvirus, Macluravirus, and Carlavirus) [, , , , , ] have been reported and characterized in yams. These viral infections restrict the international exchange of yam germplasm and have a significant impact on tuber yields and quality. For example, reports from the Ivory Coast  and western Nigeria  have described average annual yield losses of 30–50% due to virus infections. Additional constraints to increase yam production and productivity are the unavailability and associated high costs of high-quality virus-free (termed ‘clean’) seed yams and the absence of a formal seed yam certification system [5,14,15].
The lack of ‘clean’ seed yams is a major constraint to improve yam productivity in West Africa. In fact, the accumulation of viruses in the yam vegetatively propagated germplasm has led to an endemic situation in the West African ‘yam belt’, a region that extends from Western Cameroon to Nigeria, Benin, Togo, Ghana, and Côte d’Ivoire. Njukeng et al.  further concluded that another main factor contributing to the high incidence and distribution of viruses infecting yam was the lack of sensitive and field-based diagnostic tools. Therefore, the development of robust and low-cost diagnostic methods is critical to assist the production and certification of disease-free seed yams.
GS and SES conceived and designed the experiments; GS, JO and CKN performed the experiments; GS, JO, CKN, MB and PLK analysed the data; PLK contributed materials; GS drafted the manuscript; All authors edited, read and approved the final manuscript.
The authors declare no conflict of interest.