3. Blotched aleurone. In the 1935 linkage summary the blotched aleurone gene (Bh) was shown to give 26% recombination with Y; no other linkages involving Bh were reported. This past summer I obtained data showing that Bh was close to Pl. I mentioned this to Dr. Emerson and he dug up from his old records data which show the same close linkage. I was interested in the Bh locus because of the Bh-c interaction. As Emerson found out years ago seeds of A R c Bh are not colorless but have irregular patches or blotches of color in the aleurone. In order to test the hypothesis that Bh was a gene stimulating the mutability of recessive c in the same way that Dt affects a I made a number of crosses involving a chromosome 9 lacking the C locus. The deficient chromosome 9, obtained from McClintock, had lost that portion of the short arm from the terminal knob to and including the C locus. Sh was not included in the deficiency. Plants carrying this deficient chromosome with the Sh allele and a normal chromosome 9 with recessive c and sh were pollinated by c sh Bh pollen. The Sh seeds had the C locus represented by a single recessive c allele while the sh seeds had three recessive c alleles. The two classes of seeds were examined for the grade of blotching. The data clearly show that seeds with one c allele have less aleurone color than do seeds with three c alleles. The Sh and sh phenotypes have no effect on the degree of blotching. This dosage effect of c would seem to indicate that the Bh-c situation is comparable to the Dt-a.

M. M. Rhoades