Molecular Characterization of the Texas Maize Breeding Program

Abstract

The Texas maize breeding program at Texas A&M University has been unique among breeding programs for the incorporation of a wealth of germplasm from a wide range of origins into inbred lines. The Texas program, situated in a subtropical environment, has found beneficial traits beyond what is seen in the temperate material commonly used in the far more productive Midwestern region of the United States from maize of tropical origin. To date, no molecular studies had been conducted to make any quantitative differentiations between the genetic diversity in the germplasm developed in the Texas program or compared to the germplasm commonly used in breeding programs from the Midwest.

In this study a molecular characterization of genetic diversity was performed. A unique set of 266 lines were selected and genotyped using 766 single nucleotide polymorphism markers and was combined with data published in a similar study focusing on ex-PVP lines released by private companies. The two data sets combined to have 380 genotypes with 635 markers.

It was determined from the results of the genotyping that there were five subpopulations of material as determined by population structure. A principal coordinate analysis showed only 18% of the variation could be explained by the first two principal components. This suggested that the array markers, designed to cluster the Midwestern heterotic groups did not discriminate this exotic material well and/or that the heterotic pools were not well supported. We conclude that the Texas program material shows dissimilar genetic results when compared to Midwest temperate material and has the ability to act as a source of unique genetics for other maize breeding program.