Development of Maize Streak Disease Resistant Lines Using Gamma Radiation

ABSTRACT

Maize streak disease (MSD) is the most important viral disease affecting maize production in Ghana. Management options employed to mitigate the effect of the disease has not been successful. Breeding for disease resistant is the most sustainable option. Mutation breeding was used in this study to develop maize mutants’ lines that are resistant MSD. Radiosensitivity was first carried out to determine the optimum dose for mutation induction in six cultivars of maize grown in the study region. Four maize genotypes namely Obatanpa, Honampa, Pann 53 and Dapango were selected based on the radiosensitivity test results and acutely irradiated at 288.5 Gy, using a cobalt 60 (60Co) source delivering at a dose rate of 300 Gy hr-1 . The irradiated seeds were planted with controls. Separate field trials for the selected maize genotypes were conducted from M1 to M4 generations to screen for MSV resistance and improved agronomic traits. Fourteen putative mutants were selected across the four maize genotypes at the end of the M4 generation based on disease severity score and yield indices. The selected mutants were planted in a screen house and challenged with MSV to confirm resistance by polymerase chain reaction (PCR) and visual symptomology. The results indicate that, four (TZS/KPO/140001 TZS/KPO/140003 TZS/KPO/140004 and TZS/KPO/140005) out of the 14 mutants selected were resistant to MSV while the remaining ten (10) were susceptible. The four mutants were all mutated from the Obatanpa maize genotype. This study was therefore conducted to induce host plant resistant to MSD.