|Buckler, Edward - Ed|
Submitted to: Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/13/2003
Publication Date: 12/1/2003
Citation: Liu, K., Goodman, M., Muse, S., Smith, J.S., Buckler Iv, E.S., Doebley, J. 2003. Genetic structure and diversity among maize inbred lines as inferred from dna microsatellites. Genetics. 165:2117-2128. Interpretive Summary: It is well established that maize has tremendous phenotypic and molecular diversity. However, unless we fully understand the evolutionary history of the germplasm and the variation it holds, we can not harness this diversity for agronomic gain. In this study, we looked at nucleotide variation among 260 maize inbred lines and also compared diversity in these inbreds to that of open-pollinated landraces from which they were derived. Our analysis uncovered abundant genetic variation, with tropical and subtropical inbreds possessing a greater number of alleles and greater gene diversity than their temperate counterparts. Diverse maize inbreds were also found to capture about 80% of the gene variants present in the landraces. In the future, plant breeders can use these data to identify and incorporate new genes of agronomic importance, and thus tap into genetic diversity that is poorly represented in the inbred lines of today. We were also able to define core sets of inbreds, capturing the maximum number of available gene variants, for use in future maize genome research.
Technical Abstract: Although the tremendous diversity of the maize genome has been well documented, the limited scope of previous studies failed to fully characterize the genetic structure and diversity inherent in the germplasm. In this study, 260 maize inbred lines, representing the majority of genetic diversity available to breeding programs world-wide, were assayed for nucleotide polymorphisms at 94 microsatellite loci. Natural breeding groups were determined using a model-based approach, a Fitch-Margoliash tree based on SSR data was constructed, and core sets of inbreds capturing maximal allelic richness were defined. Results indicated that maize inbred lines cluster into five groups corresponding to major breeding groups. Diversity among these groups was highest for tropical-subtropical inbreds when compared to temperate lines, while diversity between inbred lines and the landraces from which they derived was higher in landraces. In the future, plant breeders can use these results to further their efforts in identifying new alleles of agronomic importance, and thus tap into genetic diversity that is poorly represented in the inbred lines of today.