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United States Department of Agriculture

Agricultural Research Service

Research Project: Develop Stress-Resistant Dry Bean Germplasm and Sustainable Pest Management Strategies for Edible Legumes

Location: Vegetable and Forage Crops Production Research

Title: Systematic presentation of a genetic notation convention for the complex C locus: C and R genes only

Authors
item Bassett, Mark -
item MIKLAS, PHILLIP
item Caldas, Gina -
item Blair, Matthew -

Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Research Notes
Publication Acceptance Date: March 5, 2011
Publication Date: April 5, 2011
Citation: Bassett, M., Miklas, P.N., Caldas, G., Blair, M. 2011. Systematic presentation of a genetic notation convention for the complex C locus: C and R genes only . Bean Improvement Cooperative Annual Report. 54:48-49.

Interpretive Summary: Although the genes C and R are tightly linked, most authors give only the genotype at C or R for any particular seed coat color expression (Bassett 2007). When the genotypes of the two parents in a cross are homozygous for one of the genes, specifying only the differences at the other gene is adequate, but when the genotype of the two parents differs at both loci, dual specification is needed for clarity. Bassett (1991) proposed using brackets to enclose the gene symbols at C and R to indicate the very tight linkage, i.e., the bracket convention. The proposed application of the bracket convention to the Liborino class genotype was given by Bassett (2007) as [C Rst], which indicates that although the red color is restricted to stripes, the remainder of the seed coat expressed C normally. To demonstrate the power of the bracket convention to express complex situations at C and R with symbolic simplicity, a systematic presentation of its possibilities is presented for the first time. To simplify the presentation, the possible interactions with red colors controlled at Rk are ignored. For the same reason, the consideration of the great variability in pattern types found at the C locus in common bean is restricted to stripes only.

Technical Abstract: Although the genes C and R are tightly linked, most authors give only the genotype at C or R for any particular seed coat color expression (Bassett 2007). When the genotypes of the two parents in a cross are homozygous for one of the genes, specifying only the differences at the other gene is adequate, but when the genotype of the two parents differs at both loci, dual specification is needed for clarity. Bassett (1991) proposed using brackets to enclose the gene symbols at C and R to indicate the very tight linkage, i.e., the bracket convention. The proposed application of the bracket convention to the Liborino class genotype was given by Bassett (2007) as [C Rst], which indicates that although the red color is restricted to stripes, the remainder of the seed coat expressed C normally. To demonstrate the power of the bracket convention to express complex situations at C and R with symbolic simplicity, a systematic presentation of its possibilities is presented for the first time. To simplify the presentation, the possible interactions with red colors controlled at Rk are ignored. For the same reason, the consideration of the great variability in pattern types found at the C locus in common bean is restricted to stripes only.

Last Modified: 8/19/2014
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