NEW RECESSIVE ALLELE AT THE C-LOCUS FOR SEED-COAT COLOR IN COMMON BEAN

inheritance of a new allele, c(nu), at the C locus for seedcoat color was studied in common bean (Phaseolus vulgaris L,) using plant introduction (PI) accession 527774 as the source of c(nu), The cross PI 527774 (yellow-brown seed) x nu BC2 5-593 (mineral-brown seed) genetic tester stock was studied in F-1 and F-2 progeny, An F-3 selection from the above cross, designated F-3 c(nu) G b nu, was crossed to 5-593 (a Florida breeding line with black seeds), and the F-1 and F-2 progeny were analyzed for color segregation, The second backcross [5-593 x F-1 (F-3 c(nu) G b nu x 5-593)] was investigated in selfed progenies from 32 random BC2-F-1 parents, Two of the BC2-F-2 progenies were further tested in BC2-F-3. A third backcross of c(nu) to 5-593 was made and analyzed, and an allelism test of c(nu) B V BC2-F-3 5-593 with the cartridge buff c(u) BC3 5-593 genetic tester stock confirmed that c(nu) is an allele at C, The gene symbol, c(nu), is proposed for the new allele because it is only expressed with V and gives a grayish-brown seedcoat, Genotypes with C/c(nu) do not show heterozygous mottling with G B nu or G b nu, and there is no difference in seedcoat color between C G B nu and c(nu) G B nu, or between C G b nu and c(nu) G b nu.