Reversion from Sweet potato feathery mottle virus in bi-parental population of new kawogo and Beauregard

Abstract

Sweet potato is a major food crop grown mainly by the rural poor who make up most of Uganda’s population. In terms of dry matter production, it is the sixth most important food crop, after rice, wheat, potatoes, maize and cassava and the second most important root crop after potato in the entire world. However, its production is greatly constrained by virus infections. The most common viruses are Sweet potato feathery mottle virus (SPFMV) and Sweet potato chlorotic stunt virus (SPCSV) found almost everywhere sweet potato is grown. Methods have been proposed for virus disease control such as use of chemicals, biological control of insect vectors and use of resistance. Resistance through reversion from virus infections is a natural mechanism among resistant plants by which previously infected plants become virus free. Reversion from sweetpotato viruses has been observed mainly in east African sweetpotato landraces such as New Kawogo whereas the American varieties such as Beauregard seldom revert. Information is lacking whether reversion is heritable. The objective of this study was to evaluate heritability of reversion from SPFMV infections in a biparental population of the resistant cultivar, New Kawogo and the susceptible cultivar Beauregard. New Kawogo and Beauregard were planted in a crossing block and were cross bred upon maturity to obtain seeds for planting to the next generation. Fifty progeny seeds were germinated, and plants graft inoculated with SPFMV. Plants were evaluated for reversion for a period of 6 weeks after graft inoculation using the indicator plant Ipomoea setosa. Many (> 50%) of the progeny plants were found to show significant (p ≤ 0.05) reversion potential from SPFMV infection. The results show that reversion is heritable and can provide a cost-effective way of managing SPFMV infection among susceptible varieties through crossing them with resistant ones. vi