Genetic Variation Among Tropical Maize Inbred Lines from NARS and CGIAR Breeding Programs

Area of Science:

• Agricultural Science
• Genetics
• Plant Breeding

Background:

• Genetic diversity is crucial for crop improvement, enabling breeders to select optimal parental lines and design effective breeding systems.
• Molecular markers provide precise tools for estimating genetic diversity and population structure in plant germplasm.

Purpose of the Study:

• To assess the genetic diversity and population structure of 151 tropical maize inbred lines.
• To identify distinct genetic groups within the maize panel for strategic breeding applications.

Main Methods:

• Genotyping of 151 tropical maize inbred lines using 10,940 single nucleotide polymorphism (SNP) markers via the DArTseq platform.
• Analysis of molecular variance (AMOVA) to partition genetic diversity.
• Population structure analysis using neighbor-joining clustering and STRUCTURE algorithms.

Main Results:

• The maize panel exhibited an average gene diversity of 0.39, with expected heterozygosity ranging from 0.00 to 0.84 (mean 0.02).
• Analysis of molecular variance revealed that 97% of allelic diversity resided within individual inbred lines, with only 3% distributed among populations.
• Both clustering and STRUCTURE analyses delineated the inbred lines into four distinct genetic groups.

Conclusions:

• The identified genetic groups provide a valuable resource for maize breeders.
• Strategic crosses between divergent subgroups are predicted to maximize heterosis and generate significant variation for breeding programs.
• Understanding the genetic architecture of this maize panel facilitates informed selection and breeding system design.