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Yam Mosaic Virus (yam + mosaic_virus)
Selected AbstractsScreening of Water Yam (Dioscorea alata L.) Genotypes for Reactions to Viruses in NigeriaJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2006B. O. Odu Abstract Studies were made to identify sources of resistance to yam viruses in Dioscorea alata. Forty genotypes of D. alata were evaluated in both the field and in the screenhouse for reactions to the yam viruses: Yam mosaic virus (YMV), genus Potyvirus; Dioscorea alata virus (DAV), genus Potyvirus; Cucumber mosaic virus (CMV), genus Cucumovirus; and Dioscorea alata bacilliform virus (DaBV), genus Badnavirus. The D. alata genotypes were planted in the field and subsequently scored for virus symptom severity. All the genotypes were also planted in an insect-proofed screenhouse, and challenged mechanically and by vectors for susceptibility to each of the viruses. Analysis of variance (anova) of the symptom severity scores showed that the genotypes responded differently (P < 0.01) to virus disease in the field. Field evaluation also showed that TDa 291 (a landrace genotype from Puerto Rico), TDa 87/01091, TDa 96-4, TDa 95-163 and TDa 289 from Nigeria, and TDa 95-25 (a landrace genotype from Ghana), had a low virus disease symptom rating. Overall screening results showed that two D. alata genotypes (TDa 289 and TDa 291) are good sources of resistance to YMV, DAV and CMV, and that they are tolerant to DaBV. [source] Survey of the incidence and distribution of viruses infecting yam (Dioscorea spp.) in Ghana and TogoANNALS OF APPLIED BIOLOGY, Issue 2 2010A.O. Eni Yam leaves were collected during surveys of major yam producing agro-ecological zones (AEZs) in Ghana (n = 628) and Togo (n = 218) respectively, in 2005. Leaf tissues were tested for Cucumber mosaic virus (CMV), Dioscorea mottle virus (DMoV), Yam mild mosaic virus (YMMV), Yam mosaic virus (YMV) and badnaviruses by enzyme-linked immunosorbent assay (ELISA), immunocapture-polymerase chain reaction (IC-PCR) and/or IC-reverse transcription-PCR (IC-RT-PCR). Eighty-one percent (370/459) and 78.9% (127/161) of symptomatic leaf samples from Ghana and Togo, respectively and 56.2% (95/169) and 57.9% (33/57) of non-symptomatic leaf samples, reacted positive to CMV, YMMV, YMV and/or badnaviruses, but DMoV was not detected. The highest incidence of YMV and badnaviruses was observed in the forest,savannah transition and Guinea savannah AEZ respectively in Ghana. In Togo, incidence of badnaviruses across the four AEZ ranged from 50 to 57.9%; however, Savane Derivée Seche AEZ had the highest incidence of badnaviruses (57.9%), YMV (34.2%) and CMV (7.9%). Mixed infection of badnaviruses and YMMV was the most frequent (105 of 276 mixed infections) in the two countries and Dioscorea alata was more heavily infected than D. rotundata in both countries. [source] Field Studies on Cross-protection against Japanese yam mosaic virus in Chinese yam (Dioscorea opposita) with an Attenuated Strain of the VirusJOURNAL OF PHYTOPATHOLOGY, Issue 2 2008H. Kajihara Abstract An attenuated strain of Japanese yam mosaic virus (JYMV), designated T-3, was evaluated for its cross-protection efficacy against virulent (native) strains of JYMV in Chinese yam (Dioscorea opposita) grown in farmers' fields in Japan. Native strains of JYMV were detected by a polymerase chain reaction-based assay in all the Chinese yam plants grown from virus-free tubers in the first growing season in the fields. In contrast, the virus was detected in only one of fifty plants grown from tubers preinoculated with T-3 during the experiments for 6 years, suggesting that T-3 consistently cross-protected against native JYMV in Chinese yam in the field. Chinese yam plants preinoculated with T-3 produced significantly greater yield of tubers per plant compared with non-inoculated plants. [source] | ||||||||||