Proteins Altered in Maize Hybrids Exhibiting Different Levels of Heterosis

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PI: Kathleen J. Newton (University of Missouri, Columbia)CoPI: Brian P. Mooney (University of Missouri, Columbia)Cross-breeding of inbred varieties within a species often leads to more vigorous and higher-yielding hybrid offspring. The phenomenon of hybrid vigor (heterosis) has been harnessed by plant breeders to improve world food production, but the underlying mechanism is still undefined. Despite several investigations showing that expression of many genes change in hybrids, the changes that are most important for the heterotic response have not yet been identified. Heterosis is especially prevalent in corn (maize). Progeny from crosses between different inbred maize lines can vary in the extent of vigor observed. To increase vigor and yield, the bioenergetic processes of photosynthesis and respiration must be optimized. Therefore, the hypothesis is that mitochondrial respiration plays an important role in heterosis. This project will examine maize hybrids exhibiting low, medium, and high heterosis to identify specific proteins whose amounts are altered with the magnitude of heterosis. Quantitative experiments based on proteomics techniques will identify the protein targets that are changed in the different hybrids. Two-dimensional gel electrophoresis and liquid chromatography-coupled mass spectrometry will be used to identify and quantify the proteins. The expected outcome will be discovery of the molecules and machinery that underlie heterosis, as well as identification of validated protein markers for heterosis. The ultimate impact of the research is related to crop improvement and it is hoped that the proteins identified will become specific targets for improving the productivity of crop plants. Successful identification of target proteins and bioenergetic processes that are consistently increased in moderate and high level heterotic hybrids will provide major clues as to the underlying molecular and biochemical explanations for the phenomenon. All the results from the project will become publicly available on a dedicated University of Missouri website and NCBI-peptidome (http://www.ncbi.nlm.nih.gov/projects/peptidome/). Additionally, this project will provide integration of research and education at several levels. Training and mentoring of a postdoctoral associate and multiple undergraduates will be provided. A "capstone" course in plant genomics will be developed for undergraduates. Educational outreach will include instruction for high school teachers and students in Missouri. Communication with the general public about issues in plant genomics and proteomics, including the topic of heterosis, will occur in two venues: the popular "Saturday Morning Science" lecture series held at the University and in "science café" discussions off-campus.