Bronze-2 gene of maize: reconstruction of a wild-type allele and analysis of transcription and splicing.
The maize Bronze-2 (Bz2) gene, whose product acts late in the anthocyanin biosynthetic pathway, has been cloned and its transcript has been mapped. We have developed a general procedure for reconstructing wild-type alleles from transposable element-induced mutants. An existing transposon-containing clone, bz2::mu1 [McLaughlin, M., and Walbot, V. (1987). Genetics 117, 771-776], was modified by replacing the region of bz2::mu1 containing the transposon with the corresponding polymerase chain reaction-amplified sequence from the progenitor allele that has no Mu insertion. Particle gun delivery of the reconstructed Bz2 gene to embryonic scutellar tissue lacking a functional Bz2 gene complemented the bz2 mutant phenotype, as demonstrated by the production of purple spots. Having cloned the wild-type allele, we then analyzed the Bz2 transcript, whose features include an 82-nucleotide 5'-untranslated leader, one small intron (78 base pairs) within the coding region, and multiple polyadenylation sites. Four Mutator transposon insertions that eliminate gene function were mapped within the 850-nucleotide transcription unit. We found that variable levels of unspliced Bz2 RNA are present in purple husk tissue; this finding may indicate that the expression of Bz2 is regulated in part at the level of transcript processing.
Nash
J
J
Department of Biological Sciences, Stanford University, California 94305-5020.
Luehrsen
K R
KR
Walbot
V
V
D000483:Alleles; D001483:Base Sequence; D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*
D004251:DNA Transposable Elements; D010940:Plant Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C076971:BZ2 protein, Zea mays