The identification and characterization of two dominant r1 haplotype-specific inhibitors of aleurone color in Zea mays.

We report the identification and characterization of two novel dominant inhibitors of aleurone color in Zea mays that interact with specific haplotypes of the r1 locus. One inhibitor locus, inr1 (inhibitor of r1 aleurone color 1), maps to the long arm of chromosome 10, distal to the TB-10L19 breakpoint and tightly linked to dull1, and the second inhibitor locus, inr2 (inhibitor of r1 aleurone color 2), maps to the long arm of chromosome 9. Dominant inhibitory alleles of inr1 and inr2 act by suppressing aleurone color conditioned by certain r1 haplotypes. Two haplotypes, R1-ch:Stadler and R1-Randolph, exhibit nearly complete suppression of aleurone color in the presence of inhibitory alleles of inr1 or inr2. Two members of the R1-d class of haplotypes, R1-d:Catspaw and R1-d:Arapaho, show partial suppression. Other haplotypes tested were not visibly affected. The response of r1 haplotypes to inhibitory inr1 and inr2 alleles provides another means of analyzing the complex behavior of the seed color components of r1 haplotypes. Possible mechanisms of action of inr1 and inr2 are discussed.