Recombinant Mutable Alleles of the Maize R Gene
Three insertions of Dissociation (Ds) into an R allele that confers strong seed color (Sc) have been transferred by crossing over into a plant color allele (P). The recombinant products show partial to complete inhibition of plant pigmentation in the absence of Activator (Ac). The rank of pigmentation levels in the sheaths of seedling leaves and in anthers is the same for the (P) recombinants as for seed color in the original (Sc) mutables. There is one reversal of rank order in coleoptiles. In the presence of Ac, intensity of sectoring in anthers parallels that in seeds of the respective (Sc) counterparts. The recombinant (P) mutables originate from (Sc)Ds/(P) heterozygotes as a reciprocal product of crossing over that restores normal (Sc) phenotype. For r-m3, both products were recovered together following meiotic nondisjunction. The transfer of mutability to (P) and the restoration of (Sc) pigmentation were used as criteria to investigate the relationship of (Sc) and (P) with other R genic elements. Transfer and restoration experiments involving (Sc) and (P) have succeeded in every combination tested. Although functional (P) derivations were obtained from (P)m-1 heterozygotes involving the R elements (S) and (D), mutable forms of these elements were not obtained. Neither transfer nor restoration occurred when (P)m-1 was combined with R-cherry, indicating a third class of R allele organization.
KeywordsTransposable Element Flank Marker Seed Color Distal Marker Intragenic Recombination
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