2 results
Wild proso millet (Panicum miliaceum) is genetically variable and distinct from crop varieties of proso millet
- Joseph C. Colosi, Barbara A. Schaal
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- Journal:
- Weed Science / Volume 45 / Issue 4 / August 1997
- Published online by Cambridge University Press:
- 12 June 2017, pp. 509-518
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- Article
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Proso millet occurs both as a crop and a weed in North America. In 1970, an olive-black seeded biotype called ‘wild proso millet’ was found as an aggressive weed in row crops in Minnesota and Wisconsin and has since spread over a large area. We used Random Amplified Polymorphic DNA (RAPD) to assess genetic relationships among biotypes, measure genetic variation within wild proso millet across its range, and detect hybridization between wild proso millet and crop biotypes of proso millet. We found 97 RAPD genotypes among 398 individuals: 69 wild proso millet genotypes, 26 crop and crop-like weed genotypes, and two hybrid genotypes. Five RAPD markers consistently differentiated wild proso millet from crop cultivars and crop-like weeds. About 10% of the genotypes had at least one marker of the other type, suggesting possible hybridization between wild proso millet and crop biotypes. Most genotypes occurred in only one or two of the over 100 populations tested. The most widespread wild proso millet genotype occurred in 12 populations distributed in North Dakota, Minnesota, Illinois, and Wisconsin. More genetic variation exists among populations of wild proso millet than expected for a plant that presumably experienced a severe genetic bottleneck only 20 generations ago. Hypermutation rates and crossing between wild proso millet and crop cultivars could not account for the degree of genetic variation found in wild proso millet. The pattern of genetic variation among wild proso millet populations suggests multiple introductions of wild proso millet to North America.
2 - Gene flow, biodiversity, and genetically modified crops: Weedy rice in Thailand
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- By Barbara Schaal, Washington University, Wesley J. Leverich, St. Louis University, Sansanee Jamjod, Chiang Mai University, Chanya Maneechote, Chiang Mai University, Anbreen Bashir, St. Louis University, Amena Prommin, Chiang Mai University, Adirek Punyalue, Chiang Mai University, Athitya Suta, Chiang Mai University, Theerasak Sintukhiew, Sintukhiew, Anupong Wongtamee, Chiang Mai University, Tonapha Pusadee, Chiang Mai University, Sunisa Niruntrayakul, Chiang Mai University, Benjavan Rerkasem, Chiang Mai University
- Edited by J. Andrew DeWoody, Purdue University, Indiana, John W. Bickham, Purdue University, Indiana, Charles H. Michler, Purdue University, Indiana, Krista M. Nichols, Purdue University, Indiana, Gene E. Rhodes, Purdue University, Indiana, Keith E. Woeste, Purdue University, Indiana
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- Book:
- Molecular Approaches in Natural Resource Conservation and Management
- Published online:
- 05 July 2014
- Print publication:
- 14 June 2010, pp 35-49
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Summary
The domestication of plants and animals and the development of agriculture some 10,000 years ago has led to profound changes in the environment and to biodiversity (Diamond 1997; Smith 1998). As natural communities were replaced by pastures and fields, native species were displaced or their habitats fragmented (Heywood 1995; Millennium Ecosystem Assessment 2005). The extirpation of native species began with the earliest agricultural communities in the Middle East and Asia and continues today. Every major advance in agriculture, from the development of new crops to mechanized farming, has environmental consequence. The most recent change in agricultural practice is the planting of genetically modified (GM) crops. First developed and legalized in the 1990s, today the majority of crops in the United States are GM, with approximately 90% of the U.S. soybean crop GM for herbicide tolerance (U.S. Department of Agriculture 2008).
GM crops are varieties that have been transformed by using a biological or physical method to insert specific genes into a genome (Chrispeels & Sadava 2003). The inserted genes, transgenes, can come from another species or from the same species. In contrast, most varieties of nontransgenic crops are produced by traditional and modern methods of crop improvement and selective breeding (Chrispeels & Sadava 2003). Other descriptions for such GM crops are recombinant or genetically engineered crops. The specific methods of genetic manipulation used to produce a GM crop are not thought to have any serious consequences (National Research Council 2002), but rather the consideration of most concern is the specific nature of the introduced transgene. Because the method of crop improvement has little effect, some researchers have argued that the distinction between GM crops and non-GM crops is artificial; crops produced by traditional means of plant breeding are also GM (Federoff & Brown 2004). This point is important: The issues and concerns that have been raised about recently developed GM crops are also of concern regarding traditional crop varieties.