ABSTRACT
Aims of the Study: This study was to determine the amino acid profile of two newly developed quality protein maize varieties and to develop variety-diagnostic molecular markers. Methodology: Two new maize varieties, named MUDISHI 1 and MUDISHI 3 have been developed by breeders and farmers using the participatory breeding approach. Total protein and amino acid profiles of the two new lines were compared to their respective parental population and a locally released genetically improved normal maize variety. Maize accessions from the DR-Congo breeding program were analyzed using ISSR primers. Variety-diagnostic markers were identified and characterized. Results: Protein analysis data revealed that MUDISHI 1 and MUDISHI 3 are QPM varieties that are distinct from their original population, Longe 5 QPM from NARI- Unganda and DMR-ESR-W-QPM from the International Institute for Tropical Agriculture (ITTA, Ibadan), respectively. Lysine content in MUDISHI 1, and MUDISHI 3 were 3.5 g and 3.6 g of lysine / 100 g, respectively, which represents a significant increase of 20% and 23% over the genetically improved normal maize variety (Salongo 2) that is currently released. There was a significant increase of 25% of tryptophan and 33% of methionine in MUDISHI 3 compared to its parental variety while the amount of lysine was similar for the two varieties. There were 10% and 15% decrease of lysine and tryptophan, respectively in MUDISHI 1 compared to its original parent Longe 5 QPM. Genomic DNA was extracted from different maize varieties. One ISSR diagnostic-marker of 480 bp that was identified was unique to the QPM variety MUDISHI 3. This sequence was converted to a sequence characterized amplified region (SCAR) marker using a pair of designed primers. This SCAR sequence was not specific to MUDISHI 3 as it was present in all the varieties tested. Conclusion: The newly developed varieties are typical QPM lines. The development of an ISSR diagnostic marker indicates that it is possible to develop a molecular breeding program involving QPM and normal varieties.
ABSTRACT
Cassava serves as primary staple food of millions of people in the tropics and subtropics, and is used as a carbohydrate source in animal feed. Knowledge of agro-morphological characteristics and genetic relatedness is essential for an efficient recombination of varieties in a breeding program. The objective of the present study was to determine genetic relatedness and morpho-agronomic differentiation among Congolese cassava collection for breeding purposes. The morphological and agronomic characters were highly variable among accessions. Every accession could be differentiated from any other one. There were significant genotypes x location interactions for storage root yields. Root weights were positively correlated with the number of roots per plant. In general, all the improved varieties were tolerant or resistant to the Cassava Mosaic Virus (CMV) while the local (non-improved) varieties were susceptible. But the reaction to Cassava Bacterial Blight (CBB) confirmed that genetically improved accessions are susceptible and local varieties are resistant. Molecular analysis revealed that the accessions analyzed were genetically distant with 80% of genetic distance values estimated above 0.5. One local accession was an out-group that was separated from the main groupings with 100% degree of confidence. More importantly, there were no associations between genetic relationships and morphological similarities based on lobe shape, leaf colour, petiole colour, petiole orientation, and stem colour. Although the Congolese cassava genepool is small, there is enough variability to sustain a breeding program without new introductions of germplasms.