Molecular analysis of quality protein (QPM) and normal maize varieties from the DR-Congo breeding program
In recent years, the use of quality protein maize (QPM) with the objective of improving the nutritional value of maize grain protein has been the focus of several African breeding programs. Knowledge of genetic variation among QPM and normal maize varieties is important for an efficient selection and development of new varieties.The main objective of this study was to assess the level of genetic variation and relatedness among and within QPM and normal maize varieties selected in the DR-Congo breeding program using inter-simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) markers. For ISSR analysis, the mean level of polymorphism within each accession analyzed was 69%. Nei’s gene diversity (h) was 0.26 on the average. The genetic distance among the accessions varied from 0.098 to 0.460. More than 80% of genetic distances were below 0.35. The mean level of polymorphic loci among accessions obtained with RAPD markers was higher (79%) compared to ISSR. The genetic distance values were also larger than ISSR data ranging from 0.16 to 0.61 with 50% of values smaller than 0.35. The mean level of polymorphisms within the accessions analyzed was 65%. The Nei’s gene diversity (h) was 0.23. Overall, the genetic variation among and within QPM and normal varieties were high, but the genetic distance among them was small. QPM accessions clustered together, but the genetic closeness among QPM and normal maize varieties studied was not always related to their origin.
Key words: Quality protein maize, normal maize, genetic variation, genetic relatedness, inter-simple sequence repeat (ISSR), random amplified polymorphic DNA (RAPD), DR-Congo.