Mode of Gene Action to Maize Streak Virus in Mid Altitude Inbred Lines CML202 and Osu23i
Peter Lorroki, James Muthomi, JaneIninda, Lilian Gichuru, Stephen Githiri, MainaWagacha

Abstract
Maize streak virus disease (MSVD) is the most destructive viral disease of maize in Africa causing significant effects on maize yields. Since breeding for durable resistance is an essential trait to improved maize varieties in sub-Saharan Africa, it is important to understand genetic systems conditioning resistance in diverse sources. The objective of this study was to determine the mode of gene action in two maize inbred lines, susceptible CML202 and immune Osu23i. Two sets of six generations (P1, P2, F1, BC1:1, BC1:2 and F2) derived from parental and bi-parental crosses of the MSV susceptible parent EM11-133, and CML202 and immune Osu23i were planted in two trials. MSV mean scores and variance rated on individual plants were fitted onto an additive-dominance model. Results indicated that additive gene effect control resistance to MSV in CML202 and Osu23i with the dominance, additive x additive and additive x dominance genic effects playing an important role in selection. The number of effective factors was estimated to be between 2 and 7 genes. Based on frequency distribution of MSV scores in segregating population (BC1:1, BC1:2 and F2), two separate genetic systems appear to be involved in control of MSV. Therefore, maize streak virus is controlled through partial resistance in CML202 while complete resistance is responsible in Osu23i.

Full Text: PDF