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We describe a family of 3 dominant r1 haplotype-specific enhancers of aleurone color in Zea mays. Stable alleles of the 3 enhancement of r1 loci (enr1, enr2, and enr3) intensify aleurone color conferred by certain pale and near-colorless r1 haplotypes. In addition, unstable alleles of enr1 act on the same set of r1 haplotypes, producing spotted kernels. Components of this instability cross react with the Fcu system of instability. Two of the enr loci are linked with one another but none of the 3 are linked with r1. The r1 haplotypes affected by enr alleles overlap those affected by the inr family of r1 haplotype-specific inhibitors of aleurone color, suggesting a possible interaction.

The Spotted-dilute controlling element system in maize involves an autonomous Spotting factor (Spf), and a receptor at the r1 locus haplotype R1-r(spotted dilute2). Its relationship with other maize transposable element systems is poorly characterized. Through development of a genetic tester that carries receptors for both the Spotted-dilute and the En/Spm controlling element systems, we determined that both receptors respond equally to Spf and En/Spm and that Spf is therefore a member of the En/Spm family of controlling elements.

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.

Anaerobic tolerant null (ATN) is a recessive factor that allows alcohol dehydrogenase-1 (ADH1) null individuals of Zea mays L. to survive 24 h of anaerobic conditions. ADH1 null lines that do not possess this factor survive only a few hours of anoxia. We studied ADH activity levels in protein extracts from the primary root tissue of ATN. ADH levels were similar in ATN and other ADH1 null lines, suggesting that ADH activity does not account for differences in the ability of ATN to survive anaerobic treatment. The ATN survival trait segregated as a single recessive locus in crosses between ATN and double null (Adh1-S5657, Adh2-33). We also made crosses between ATN and 1s2p, an inbred line with ADH1 activity that carries an electrophoretic mutation of Adh2, to determine whether atn increases the number of survivors over that which would be expected from the segregation of Adh1 alone and to use the Adh2P allele to study the cosegregation of Adh2 and atn. The observed number of survivors in that cross exceeded the expected number of survivors by a margin consistent with a single recessive gene adding to the ADH+ survivors. Extracts from the primary root or scutellum of induced F2 seedlings from the above crosses were assayed for ADH activity by native polyacrylamide gel electrophoresis (PAGE) and simultaneously scored for survival to determine whether Adh2 and atn were segregating independently. We screened the (ATN x 1s2p)F2 progeny for ADH1 activity by staining root tips with an ADH-specific stain to select Adh1 null individuals prior to gel assay. Atn was found to be assorting independently of Adh1 and Adh2 in both crosses.