Screening Ten Yam (Dioscorea spp.) Varieties for Resistance to Yam mosaic virus and Cucumber mosaic virus in Cote d'lvoire

摘要

Yam (Dioscorea spp.) production in Cote d'lvoire is threatened by viral diseases. In order to provide high-yielding yam varieties to rural populations, the Swiss Center for Scientific Research (CSRS) obtained improved varieties from the IITA breedingprogram in Nigeria. Seven of these improved varieties (including D. alata and D. cayenensis-rotundata complex), selected for their good organoleptic characteristics and agronomic performances, as well as three locally grown varieties (Krengle, Betet-beteand Florido) were evaluated after mechanical inoculation with Yam mosaic virus (YMV) and Cucumber mosaic virus (CMV) separately. The parameters measured included disease severity (scores and indexes) and virus accumulation (overtime and in different plant parts) as determined by the enzyme-linked immunosorbent assay (ELISA) test. The results showed that all varieties became infected with YMV and all but Krengle became infected with CMV. That variety seemed immune to CMV infection. Varieties TDr 89/02665, TDr 96/02629 and TDa 00/00010 were resistant to YMV. These varieties, in addition to TDr 95/18544, were also found to be resistant to CMV. Regardless of the virus, its accumulation depended on the variety, the plant parts tested and the physiologicalstage of the plants.