Analysis of Maize Brittle-1 Alleles and a Defective Suppressor-Mutator-Induced Mutable Allele

• Published in: The Plant cell 1991-12, Vol.3 (12), p.1337-1348
• Main Authors: Sullivan, Thomas D., Strelow, Lisa I., Illingworth, Charles A., Phillips, Ronald L., Nelson, Oliver E.
• Format: Article
• Language: English
• Subjects: Alleles; Amino Acid Sequence; Amino acids; Base Sequence; Cloning, Molecular; Complementary DNA; Corn; DNA; DNA Transposable Elements; Endosperm; Genetic loci; Genomics; Membrane Proteins - genetics; Membrane Proteins - metabolism; Molecular Sequence Data; Phenotype; Plant Proteins - genetics; Plant Proteins - metabolism; RNA; Sequence Homology, Amino Acid; Suppression, Genetic; Transposons; Zea mays - genetics
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.3.12.1337

A mutant allele of the maize brittle-1 (bt1) locus, brittle-1-mutable (bt1-m), was shown genetically and molecularly to result from the insertion of a defective Suppressor-mutator (dSpm) transposable element. An Spm-hybridizing restriction enzyme fragment, which cosegregates with the bt1-m allele and is absent from wild-type revertants of bt1-m, was identified and cloned. Non-Spm portions of it were used as probes to identify wild-type (Bt1) cDNAs in an endosperm library. The 4.3-kb bt1-m genomic clone contains a 3.3-kb dSpm, which is inserted in an exon and is composed of Spm termini flanking non-Spm sequences. RNA gel blot analyses, using a cloned Bt1 cDNA probe, indicated that Bt1 mRNA is present in the endosperm of developing kernels and is absent from embryo or leaf tissues. Several transcripts are produced by bt1-m. The deduced translation product from a 1.7-kb Bt1 cDNA clone has an apparent plastid transit peptide at its amino terminus and sequence similarity to several mitochondrial inner-envelope translocator proteins, suggesting a possible role in amyloplast membrane transport.