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Title: Genetic diversity among tropical provitamin A maize inbred lines and implications for a biofortification program

item SSERUMAGA, JULIUS - National Agricultural Research Organization - Uganda
item MAKUMBI, DAN - International Maize & Wheat Improvement Center (CIMMYT)
item OPIYO, STEPHEN - The Ohio State University
item Warburton, Marilyn
item ASEA, GODFREY - National Agricultural Research Organization - Uganda
item MUWONGE, ABU-BAKER - National Agricultural Research Organization - Uganda

Submitted to: Cereal Research Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2018
Publication Date: 2/22/2019
Citation: Sserumaga, J.P., Makumbi, D., Opiyo, S.O., Warburton, M.L., Asea, G., Muwonge, A. 2019. Genetic diversity among tropical provitamin A maize inbred lines and implications for a biofortification program. Cereal Research Communications. 47(1):134-144.

Interpretive Summary: In developing countries, vitamin A deficiency (VAD) affects up to 140 million children and pregnant women, and can cause blindness, immune system deficiency, and stunting of growth; these conditions can be lethal. In countries where, due to poverty and habit, the majority of food calories come only from corn, vitamin and mineral deficiencies are very common. To improve nutrition, corn with higher natural vitamin and mineral content can be created by breeders, in a process called biofortification, if corn lines with higher levels can be identified and crossed with local corn lines. In this study, sources of high provitamin A (which is converted to vitamin A in the human body) from the International Maize and Wheat Improvement Center in Mexico were introduced into Uganda to use as sources for biofortification of new Ugandan maize varieties. Sixty three of these lines were first genotyped with genetic markers to determine how they are related to each other as the first step towards determining how they will be used in the Ugandan biofortification breeding program. They were found to be very diverse, and five subpopulations of related lines were found in the overall population.

Technical Abstract: Insights of the diversity and relationships among elite breeding materials are an important component in maize improvement programs. We genotyped 63 provitamin A maize inbred lines using 137 single nucleotide polymorphism (SNP) markers to assess (i) the level of molecular diversity and population structure among the maize inbred lines, and (ii) the relationships among the set of maize lines for better exploitation in a breeding program. A total of 272 alleles were detected with gene diversity of 0.359. The average genetic distance was 0.358 with 56% of the pairs of lines having between 0.300 and 0.400. Eighty-six percent of the pairs of lines showed relative kinship values <0.500, which indicated that the majority of these provitamin A inbred lines were unique. Results of neighbor joining (NJ) clustering revealed three major groups with seven subgroups. Relationship pattern and population structure analysis revealed the presence of five major groups with good agreement with NJ clustering but not clearly correlated with pedigree. Use of these provitamin A lines in a new biofortification program will be aided by information from both molecular-based grouping and pedigree analysis. The results from this study should guide breeders to select parents with diverse alleles for new breeding starts, marker assisted breeding, and mapping population development in a provitamin A breeding program.