structure and paramutagenicity of the R-marbled haplotype of Zea mays

• Published in: Genetics (Austin) 1999-10, Vol.153 (2), p.979-991
• Main Authors: Panavas, T, Weir, J, Walker, E.L
• Format: Article
• Language: English
• Subjects: aleurone layer; anthocyanins; Base Sequence; chromosome mapping; Crosses, Genetic; crossing over; DNA Primers; DNA Transposable Elements; genbank/af135456; genbank/af135457; genbank/af135458; genbank/af136220; genbank/af136221; gene copy number; gene dosage; Genes, Plant; Haplotypes; Heterozygote; lcm1 gene; lcm2 gene; Meiosis; Molecular Sequence Data; multiple genes; Mutagenesis; mutagenicity; mutation; nucleotide sequences; paramutations; pigmentation; Polymerase Chain Reaction; r1 gene; Recombination, Genetic; regulator genes; Restriction Mapping; transcription factors; transposons; variegation; Zea mays; Zea mays - genetics
• ISSN: 0016-6731; 1943-2631; 1943-2631
• DOI: 10.1093/genetics/153.2.979

Paramutation is the meiotically heritable silencing of a gene that can occur in particular heterozygous combinations. The R-marbled (R-mb) haplotype is paramutagenic: it causes paramutable r1 haplotypes like R-r to become heritably silenced. R-mb was found to comprise three distinct r1 genes arranged as direct repeats. The most distal gene of R-mb, Scm, contains a novel transposable element, Shooter (Sho). Excision of the Sho element early in aleurone development results in the characteristic "marbled" aleurone pigmentation pattern conferred by R-mb. The effect of gene copy number on the paramutagenic strength of R-mb was tested. Paramutagenic strength of R-mb is directly correlated with r1 gene copy number. Paramutagenic strength of R-mb is directly correlated with r1 gene copy number. Paramutagenic strength of R-mb was not affected by removal, through crossing over, of the Sho transposon. Finally, R-mb does not appear to contain the transposable element, Doppia, which is associated with paramutability of R-r, and has been suggested to play a role in paramutagenicity of another paramutagenic haplotype, R-stippled.