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Transcription Factor Families Regulate the Anthocyanin Biosynthetic Pathway in Capsicum annuum

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Anthocyanin structural gene transcription requires the expression of at least one member of each of three transcription factor families: MYC, MYB, and WD40. These transcription factors form a complex that binds to structural gene promoters, thereby modulating gene expression. Capsicum annuum L. (pepper) displays a wide spectrum of tissue-specific anthocyanin pigmentation, making it a useful model for the study of anthocyanin accumulation. To determine the genetic basis for tissue-specific pigmentation, we used real-time polymerase chain reaction to evaluate the expression of anthocyanin biosynthetic (Chs, Dfr, and Ans) and regulatory (Myc, Myb(A), and Wd) genes in flower, fruit, and foliar tissue from pigmented and nonpigmented C. annuum genotypes. No differences were observed in expression of the Wd gene among these tissues. However, in all cases, biosynthetic gene transcript levels were significantly higher in anthocyanin-pigmented tissue than in nonpigmented tissues. Myb(A) and Myc transcript levels were also substantially higher in anthocyanin-pigmented floral and fruit tissues. Our results demonstrate that differential expression of C. annuum Myb(A) as well as Myc occurs coincident with anthocyanin accumulation in C. annuum flower and fruit tissues. In contrast to the situation in flowers and fruit, differential expression of Myb(A) and Myc was not observed in foliar tissue, suggesting that different mechanisms contribute to the regulation of anthocyanin biosynthesis in different parts of the C. annuum plant. Cloning and sequencing of Myb(A) genomic and cDNA clones revealed two introns of 249 and 441 bp between the R2R3 domains. Whereas the Myb R2R3 domains were conserved between C. annuum and Petunia xhybrida Vilm., the sequence of the non-R2R3 domains was not conserved, with very little homology in these related Solanaceous species.
Stommel, John R. , Lightbourn, Gordon J. , Winkel, Brenda S. , Griesbach, Robert J.
Capsicum annuum , sweet peppers , anthocyanins , biochemical pathways , transcription factors , gene expression , transcription (genetics) , promoter regions , DNA-binding proteins , polymerase chain reaction , plant pigments , flowers , fruits (plant anatomy) , leaves , plant tissues , spatial variation , complementary DNA , introns
p. 244-251.
Includes references
Journal of the American Society for Horticultural Science 2009 Mar., v. 134, no. 2
Journal Articles, USDA Authors, Peer-Reviewed
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