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Title: Wide Variability in Seed Characteristics, Kernel Quality, and Zein Profiles Among Diverse Maize Inbreds, Landraces, and Teosinte

Author
item Flint-Garcia, Sherry
item BODNAR, ANASTASIA - IOWA STATE UNIVERSITY
item Scott, Marvin

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2009
Publication Date: 8/24/2009
Citation: Flint Garcia, S.A., Bodnar, A., Scott, M.P. 2009. Wide Variability in Seed Characteristics, Kernel Quality, and Zein Profiles Among Diverse Maize Inbreds, Landraces, and Teosinte. Theoretical and Applied Genetics. 119:1129-1142.

Interpretive Summary: All crop species have been domesticated from their wild relatives, resulting in decreased genetic variation in the domesticate compared to the ancestor. Geneticists are just now beginning to understand the genetic consequences of selection on the agronomic traits that are relevant today. It is, therefore, also critical to understand the growth, physiology, and other various attributes of the wild relatives from which the crop has evolved. This is especially true for corn (maize), where its wild ancestor, teosinte, is so strikingly different from modern day maize. We evaluated seed characteristics, kernel composition, and profiles of the zein seed storage proteins for a diverse set of modern inbred lines, teosinte collections, and landraces (the evolutionary intermediate between inbreds and teosinte). We found that both teosinte and landraces vary significantly from modern inbreds and landraces for the majority of the traits we looked at. We have determined that teosinte and landraces harbor useful phenotypic variation that will be essential to geneticists in their attempts to understand the genetic architecture of agronomically and evolutionarily relevant traits. This information will also be valuable breeders who strive for corn improvement via traditional plant breeding and/or biotechnology.

Technical Abstract: All crop species have been domesticated from their wild relatives, and geneticists are just now beginning to understand the genetic consequences of artificial (human) selection on agronomic traits that are relevant today. The major consequence is severe reduction in genetic diversity for genes underlying traits that experienced selection. It is critical to understand the growth, physiology, and other various attributes of the wild relatives from which the crop has evolved. This is especially true for maize (Zea mays ssp. mays), where its wild ancestor, teosinte (Zea mays ssp. parviglumis), is so strikingly different from modern maize. One obvious target of selection in maize is the size and composition of the kernel. We evaluated kernel characteristics, kernel composition, and zein profiles for a diverse set of modern inbred lines, teosinte accessions, and landraces (the evolutionary intermediate between inbreds and teosinte). We found that the very small teosinte seeds had twice the protein content as landraces and inbred lines, but the same embryo to endosperm ratio. While teosinte had a higher alpha zein content (nearly 40% of total zeins) as compared to 12-15% for inbred lines and landraces, there were many novel peaks in teosinte relative to the other two germplasm groups. The methionine-rich beta and delta zeins were present in higher abundance in landraces and/or teosinte than in inbred lines. Teosinte and landraces harbor useful phenotypic variation that will lend itself to genetic dissection of kernel traits, and to improvement via traditional plant breeding and/or genetic engineering.