Characterization of New Quality Protein Maize (QPM) Varieties from a Breeding Program: Analysis of Amino Acid Profiles and Development of a Variety-Diagnostic Molecular Marker

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.