Abstract
Genetic adaptation of maize to the increasingly unpredictable climatic conditions is an essential prerequisite for achievement of food security and sustainable development goals in sub-Saharan Africa. The landraces of maize; which have not served as sources of improved germplasm; are invaluable sources of novel genetic variability crucial for achieving this objective. The overall goal of this study was to assess the genetic diversity and population structure of a maize panel of 208 accessions; comprising landrace gene pools from Burkina Faso (58), Ghana (43), and Togo (89), together with reference populations (18) from the maize improvement program of the International Institute of Tropical Agriculture (IITA). Genotyping the maize panel with 5974 DArTseq-SNP markers revealed immense genetic diversity indicated by average expected heterozygosity (0.36), observed heterozygosity (0.5), and polymorphic information content (0.29). Model-based population structure; neighbor-joining tree; discriminant analysis of principal component; and principal coordinate analyses all separated the maize panel into three major sub-populations; each capable of providing a wide range of allelic variation. Analysis of molecular variance (AMOVA) showed that 86% of the variation was within individuals; while 14% was attributable to differences among gene pools. The Burkinabe gene pool was strongly differentiated from all the others (genetic differentiation values >0.20), with no gene flow (Nm) to the reference populations (Nm = 0.98). Thus; this gene pool could be a target for novel genetic variation for maize improvement. The results of the present study confirmed the potential of this maize panel as an invaluable genetic resource for future design of association mapping studies to speed-up the introgression of this novel variation into the existing breeding pipelines.
Highlights
Maize (Zea mays L.) is one of the most important cereal crops consumed in sub-Saharan Africa (SSA) and an essential component of livestock feed in the developed as well as developing world.Genes 2020, 11, 1054; doi:10.3390/genes11091054 www.mdpi.com/journal/genesApproximately 10,000 years ago in Central Mexico, maize was domesticated from its ancestor, the wild grass-teosinte (Zea mays spp. parviglumis) [1]
Faso and Togo were sourced from the gene bank at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, whereas those from Ghana were provided by the Plant Genetics Resources
He, Ho, minor allele frequency (MAF), and polymorphic information content (PIC) values estimated for the entire maize panel
Summary
Maize (Zea mays L.) is one of the most important cereal crops consumed in sub-Saharan Africa (SSA) and an essential component of livestock feed in the developed as well as developing world.Genes 2020, 11, 1054; doi:10.3390/genes11091054 www.mdpi.com/journal/genesApproximately 10,000 years ago in Central Mexico, maize was domesticated from its ancestor, the wild grass-teosinte (Zea mays spp. parviglumis) [1]. The landraces, though typically low in yield, are invaluable sources of diversity that could be drawn upon to broaden the genetic base of elite maize germplasm, and to further enhance adaptation to changing environments and pathogens [6]. Earlier breeders identified and composited the most productive landraces into genetically diverse populations, forming the foundation of inbred line development and pedigree breeding [7]. In which a narrow range of inbred lines are included in crossing programs, have narrowed the genetic base of most cultivated crops, which have negatively affected the adaptability of the crop to changing climates, devastating pathogens, and insect-pests [8]. In order to provide a buffer against the possible effects of novel threats, it is essential to broaden the genetic base of breeding populations by introgressing an enlarged pool of beneficial alleles
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