BGN 2: Morphological and chemical analyses of putative 2-row induced mutants in barley BARLEY GENETICS NEWSLETTER, VOL. 2, II. RESEARCH NOTES
Redlinger and Nilan, p. 70

II.26. Morphological and chemical analyses of putative 2-row induced mutants in barley.

Thomas Redlinger and R. A. Nilan. Department of Agronomy and Soils, Washington State University, Pullman, Washington 99163, U.S.A.

Two 2-row plants, Selections 8033 and 8035, arose from a chemically treated (ethyl methanesulfonate or EMS) 6-row spring barley, Gem x Traill. Another 2-row variant was found among M2 plants of the 6-row winter barley, Kamiak, following chemical treatment (EMS). Isolation of M1 plants of both 6-row varieties was considered adequate and thus the three 2-row plants were suspected of being induced mutants. The purpose of this investigation was to determine if the 2-row plants were the result of a mutation at the V-locus, the site on chromosome 2 governing the 2-row versus 6-row trait. True mutations from 6-row to 2-row have not yet been detected in barley.

Methods of investigation included analyses of morphological traits, malting quality data, electrophoretically fractioned ethanol and buffer (Tris pH 6.7) soluble protein, alpha amylase isozyme zymograms, and reactions to powdery mildew (Erysiphe graminis DC, CR3). The majority of the research was carried out on Selection 8033 and 8035 whereas fewer investigations involved the Kamiak 2-row variant.

Preliminary analyses of morphological traits and malting data indicated that Selections 8033 and 8035 might qualify as genuine mutants. Later investigations with electrophoretic protein patterns demonstrated dissimilarity between the identical patterns given by Selections 8033 and 8035 and their mother line, Gem x Traill (Selection 6124). There was a total of six band differences when three separate protein fractions were electrophoretically divided. This type of protein evidence does not conclusively disprove that a mutation had occurred at the V-locus, but it does indicate a necessity for further investigation of other possibilities.

Mildew resistance to Erysiphe graminis, CR3, was found in Selections 8033 and 8035 whereas Gem x Traill was totally susceptible. Moreover, Selection 8033 was still segregating for the monogenetically inherited Mlg-locus. A scheme was suggested whereby a combination of mutagen effects and outcross contributions would present a plausible alternative to a mutation for the origin of the 2-row plants while at the same time account for all experimental data.

The proposed scheme for the origin of the Kamiak variant also suggested that an outcross in the M1 generation was the most probable alternative. Subsequent breeding behavior suggested in the Kamiak case that the V-locus is complex in nature with the 2-row more or less dominant to the 6-row trait.

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