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Title: Phenotypic and genomic analyses of a fast neutron mutant population resource in soybean

item Bolon, Yung Tsi
item HAUN, WILLIAM - University Of Minnesota
item XU, WAYNE - University Of Minnesota
item Grant, David
item STACEY, MINVILUZ - University Of Missouri
item Nelson, Rex
item GERHARDT, DANIEL - Roche Nimblegen, Inc
item JEDDELOH, JEFFREY - Roche Nimblegen, Inc
item STACEY, GARY - University Of Missouri
item MUEHLBAUER, GARY - University Of Minnesota
item ORF, JAMES - University Of Minnesota
item NAEVE, SETH - University Of Minnesota
item STUPAR, ROBERT - University Of Minnesota
item Vance, Carroll

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2011
Publication Date: 5/1/2011
Citation: Bolon, Y.E., Haun, W.J., Xu, W.W., Grant, D.M., Stacey, M.G., Nelson, R., Gerhardt, D.J., Jeddeloh, J.A., Stacey, G., Muehlbauer, G.J., Orf, J.H., Naeve, S.L., Stupar, R.M., Vance, C.P. 2011. Phenotypic and genomic analyses of a fast neutron mutant population resource in soybean. Plant Physiology. 156(1):240-253.

Interpretive Summary: Soybean is the second most widely grown crop in the United States. It is a mainstay in U.S. agriculture. Conventional breeding and biotechnology have been the primary approaches to improving soybean yield and quality. The development of mutant lines of animals and plants have been instrumental to understanding the genetic regulation of many traits including diseases, nutritional quality, and growth. The objectives of this study were to develop a population of soybean lines that had been exposed to fast neutrons (energy particles). Exposure of soybean seeds to fast neutrons causes chromosome breakage and the deletion of genes. The deletions can range in size from 500 base pairs of DNA up to more than 500,000 base pairs of DNA or more. The soybean seeds exposed to fast neutrons are not radioactive nor are they transgenic (contain foreign genes). In this study we have produced 20,000 independent lines of soybeans that were exposed to fast neutrons with the objectives that deleted parts of the soybean genome will provide clues to the function of those deleted genes. We found more than 500 soybean lines that were visibly altered in growth and development. For many lines we have also altered seed protein, oil, and or fatty acids. We genetically characterized 30 lines and determined which genes were deleted. We also did DNA sequencing to prove where those genes were located in the soybean genome. Some of the soybean lines that were found had altered maturity dates, more protein in seed, and more upright growth. These studies are important because traits resulting from fast neutron mutagenesis may be useful to soybean breeders and farmers. In addition, the development of novel genetic lines of soybean will be made available to soybean scientists who study genetics, breeding, and agronomy.

Technical Abstract: Mutagenized populations have become indispensable resources for introducing variation and studying gene function in plant genomics research. In this study, fast neutron (FN) radiation was used to induce deletion mutations in the soybean (Glycine max (L.) Merrill) genome. Approximately 120,000 soybean seed were exposed to FN radiation doses of up to 32 Gy to develop more than 23,000 independent M2 lines. Here, we demonstrate the utility of this population for phenotypic screening and associated genomic characterization of striking and agronomically important traits. Plant variation was cataloged for seed composition, maturity, morphology, pigmentation, and nodulation traits. Mutants that showed significant increases or decreases in seed protein and oil content across multiple generations and environments were identified. Using comparative genome hybridization (CGH), a subset of mutants was characterized, revealing deletion regions and candidate genes associated with phenotypes of interest. The application of CGH to lesion-induced mutants for deletion mapping was validated on a mid-oleate X-ray mutant M23 with a known FAD2-1A gene deletion. Exome resequencing and sequencing of PCR products confirmed FN-induced deletions detected by CGH. We present this FN mutant soybean population as a valuable public resource for future genetic screens and functional genomics research.