ANALYSIS OF RESISTANCE TO YAM MOSAIC VIRUS,GENUS POTYVIRUS IN WHITE GUINEA YAM(DIOSCOREA ROTUNDATA POIR.) GENOTYPES

Resistance to Yam mosaic virus (YMV), genus Potyvirus wasstudied in 10 populations of selected white Guinea yam (Dioscorea rotundata).Plants of resistant genotypes: TDr 35, TDr 1621, TDr 93-1, TDr 93-32, TDr 95-107, TDr 93-23, and susceptible ones: TDr 87/00211, TDr 87/00571 and TDr95-127 were screened for their reaction to the pathogen by symptom severityscoring scale of 1-5, and by quantifying virus multiplication by triple antibodysandwich enzyme-linked immunosorbent assay (TAS-ELISA). Controlledcrosses were made among the genotypes within and between the groupsaccording to reactions to the pathogen. The resultant F1 progenies wereevaluated for the infection by disease symptom development and by TASELISA to detect a symptomless infection in an insect-proof screenhouse for theassessment of inheritance of resistance to YMV. A genetic analysis of thereactions of progenies derived from the D. rotundata genotypes to inoculationwith YMV strongly suggests that resistance to the virus is a dominantlyinherited trait. Segregation ratios obtained from the families indicate that at leasttwo dominant genes are involved.