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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #59982
Title: GENETIC DIVERSITY AMONG NORTH AMERICAN SPRING WHEAT CULTIVARS III: ANCESTOR CONTRIBUTIONS TO GENEPOOLS OF DIFFERENT ERAS AND REGIONS

Author
item VAN BEUNINGEN, L - UNIVERSITY OF MINNESOTA
item Busch, Robert - Bob

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The National Academy of Sciences, Committee on Genetic Vulnerability of Major Crops, reported a potential vulnerability in wheat. Because pest resistance and reduced plant height is obtained from the widespread use of only a few specific genes (genotypes), the National Academy of Science, Committee on Genetic Vulnerability of Major Crops, reported that wheat was potentially vulnerable to possible major new diseases. The use of only a few dominant varieties by the milling and baking industries further accentuated the possibility of genetic vulnerability. An example of wheat vulnerability was observed in 1993, when Fusarium head blight (scab) disease devastated a three-state region in the US and one Province in Canada, causing a loss of nearly 1 billion dollars. Normally scab attacks only localized areas. More tolerant varieties were planted in 1994, but the losses were still about 500 million dollars. A major regional effort has been initiated to increase levels of scab resistance in spring wheats. This research reports information about the ancestors of spring wheat, its origins, and characteristics of present varieties. It is important to understand the genetic diversity of spring wheat and to maintain or increase its genetic base. A broad genetic base is important for maintaining future high yields and pest resistance.

Technical Abstract: A broad genetic base for a crop species such as wheat may be important to reduce genetic vulnerability and assure long term potential for genetic gain. The number and diversity of original ancestors can provide insight into relative genetic diversity within and among gene pools. Based on the coefficient of parentage values between cultivars and ancestral lines, the relative genetic contributions of ancestral lines to spring wheat (Triticu aestivum L.) cultivars were computed for successive 25 year time periods. The cultivars were from Canada (47), the USA (133), and Mexico (90). Genetic backgrounds were studied for important changes in the ancestral base over time and to determine trends that continue today. About 124 ancestors, tracing to 32 countries on five continents, were found to have contributed to the North American spring wheat gene pool. Canadian western red spring cultivars released before 1950 had an intermediate level of ancestral diversity. Their post 1975 cultivars have narrow ancestral diversities probably due to strict quality regulations. They consist of primarily Thatcher germplasm modified by a set of pest resistance genes carefully managed in backcross schemes. Before 1950, the US hard red spring wheat cultivars traced to the same Thatcher ancestors, but also to Kota and Yaroslav. Many more ancestors were added to this base after 1950, and especially after 1975. This was a side effect of the incorporation of pest resistance, most notably from sources Gabo Timstein, Frontana, and Kenya 58, and reduced height sources, most notably CIMMYT cultivars with new ancestry from Kenya 324 and Turkey. CIMMYT cultivars have also expanded their genetic base over time.