Biographical Memoirs Volume 67 (1995) / Chapter Skim
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Ernest Robert Sears
Ernest Robert Sears
Pages 344-361
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From page 345... ...
In his rural school at Bethel three teachers taught four grades in a single room en c] out of school Ernie Sears's time was mainly given to farming activities.
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From page 346... ...
Papers on these subjects published in 1939 and 1941 gave considerable attention to the methodologies of coichicine treatment as well as to the relationships between chromosome pairing in the initial hybrids and the derived amphiploids. This was the origin of a lifelong involvement in the study of polyploic3 evolution and on the genetic and meiotic equivalences and distinctions between the chromosomes derived from different parents in the creation of allopolyploids.
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From page 347... ...
accepted that the application of the rules of taxonomy required the amalgamation of Aegziops and Triticum into a common genus called Triticum. However, in one of the last conversations ~ had with Sears, in 1990, he explained that he now considered that more appropriate usage required reversion to the use of the generic name "Ae~lops." GENETIC STRUCTURE OF POLYPLOIDS ANEUPLOIDS From his earliest work, Sears strove to comprehend the cytogenetic structure of hexaploid wheat.
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From page 348... ...
Next is the use of distortions of the normal Mendelian segregation ratios in F2s derived from a hybrid monosomic for a chromosome carrying the dominant allele. Expression of the recessive phenotype in monosomic FIs enables the identification of chromosomes with recessive alleles.
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From page 349... ...
In addition, using chromosome substitutions, the stem rust resistance genes in Hope, Thatcher, Red Egyptian, and Timstein were positioned on nine different chromosomes. Telocentric mapping subsequently enabled Sr9 and Sr16, respectively, from Red Egyptian and Thatcher to be placed about forty cross-over units apart along the long arm of chromosome 2B.
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From page 350... ...
Consequently, by the publication in 1954 of "The Aneuploids of Common Wheat," descriptions could be included on telocentrics or isochromosomes for every chromosome of wheat complement. By 1966 Ernie Sears could advocate genetic analysis by telocentric mapping because 42-chromosome lines, with one chromosome represented by a telocentric in the disomic condition, were available for every chromosome of the wheat complement.
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From page 351... ...
At the 1956 Brookhaven Symposium, Sears described remarkable work in which leaf rust resistance of Aeg~Zops umbellulata was transferred to common wheat. This commenced with the addition to T
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From page 352... ...
This validated the potential usefulness of centric fusion in breecling when deletion of a wheat chromosome arm is not phenotypically severe and where the added alien arm floes
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From page 353... ...
Subsequently, also in his laboratory, the work of Moshe Feldman resulted in proposals about the processes by which the Ph locus on chromosome 5B confines melotic pairing to fully homoeologous partner chromosomes. Although involved in the encouragement of work of this kind and as a frequent commentator on the genetics of chromosome pairing, Sears' direct involvement has principally concentrated on attempts to mutate the Ph locus.
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From page 354... ...
CHINESE SPRING No tribute to Ernie Sears could omit a mention of Chinese Spring, the variety that, as a result of his work, has become the reference base for all wheat cytogeneticists. Sears and T
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From page 355... ...
No matter how close or remote geographically any wheat cytogeneticist was to Ernie Sears all are in his debt. Sears enjoyed the loyalty of the Missouri Agricultural Experimental Station and the University of Missouri, Columbia, for more than five decades.
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From page 356... ...
Sears remained very fit right up to his death, playing tennis and badminton and cutting his four acres of grass at Mob Hill with only a motorized push mower. He was unflappable and simultaneously generous and frugal, the epitome of a hanc3s-on scientist.
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From page 357... ...
service USDA AWARDS 1958 Superior Service Award 1980 Distinguished Service Award 1987 Science Hall of Fame LEARNED SOCIETIES National Academy of Sciences (1964) American Academy of Arts and Sciences (1953)
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From page 358... ...
Indian Societ,v of Genetics and Plant Breeding (Honorary) American Association of Cereal Chemists (Honorary)
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From page 359... ...
Nullisomic analysis of stem-rust resistance in Triticum vulgare var. Timstein.
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From page 360... ...
Proceedings of the Fourth International Wheat Genetics Symposium, pp.
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From page 361... ...
The telocentric chromosomes of common wheat. Proceedings of the Fifth International Wheat Genetics Symposium, vol.
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