Lc, a member of the maize R gene family responsible for tissue-specific anthocyanin production, encodes a protein similar to transcriptional activators and contains the myc-homology region.

Abstract

Previous studies have suggested that the R locus of maize is responsible for determining the temporal and spatial pattern ofanthocyanin pigmentation in the plant. In this report we demonstrate that three members of the R gene family, P, S, and Lc, encode homologous transcripts 2.5 kilobases in length. The structure of one R gene, Lc, was determined by sequencing cDNA and genomic clones. The putative Lc protein, deduced from the cDNA sequence, is composed of 610 amino acids and has homology to the helixloop-helix DNA-binding/dimerization motif found in the Lmyc gene product and other regulatory proteins. It also contains a large acidic domain that may be involved in transcriptional activation. Consistent with its proposed role as a transcriptional activator is our finding that a functional R gene is required for the accumulation of transcripts of at least two genes in the anthocyanin biosynthetic pathway. We discuss the possibility that the diverse patterns of anthocyanin pigmentation conditioned by different R genes reflect differences in the R gene promoters rather than their gene products.The anthocyanin biosynthetic pathway of maize has proven to be an ideal system for understanding genetic interactions between regulatory and structural genes (for review see ref.

anthocyanin1 of Petunia Encodes a Basic Helix-Loop-Helix Protein That Directly Activates Transcription of Structural Anthocyanin Genes

“…This classification of bHLH proteins is supported by the intron-exon structures of the corresponding genes, as shown in Figure 3C. The protein coding sequences of b1, lc1, jaf13, and r a contain seven introns in conserved positions (Ludwig et al, 1989;Hu et al, 1996;Quattrocchio et al, 1998), whereas in1 contains an additional intron that splits the region encoding the weakly conserved middle domain (Burr et al, 1996). This extra intron seems to be conserved in an1, although the low sequence similarity in this region makes it impossible to assess whether both introns are in precisely the same position.…”

The promoter of the barley aleurone‐specific gene encoding a putative 7 kDa lipid transfer protein confers aleurone cell‐specific expression in transgenic rice

“…In the first set of experiments, Ltp2 promoter activity was assayed visually after histochemical staining with X-Gluc. Owing to a large variation between individual experiments, plasmid DNA containing the Lc (Ludwig et al, 1989) and C1 (Paz-Ares et al, 1987) cDNAs from maize under the control of the 35S CaMV promoter were co-bombarded with the Ltp2-Gus construct to monitor shooting efficiency. In combination, but not individually, the latter two cDNAs gave high numbers of red anthocyanin spots in the barley aleurone cells after 1-2 days of incubation of the grains on solid nutrient medium ( Figure 4c).…”

The basic helix–loop–helix domain of maize R links transcriptional regulation and histone modifications by recruitment of an EMSY-related factor

“…When present, basic regions contribute to the binding of bHLH factors to DNA, through cisregulatory elements, termed E-boxes, with the CANNTG consensus, whereas HLH motifs participate in homodimer or heterodimer formation (4). Maize R was the first plant bHLH transcription factor described (5). R belongs to a small gene family, which includes B, and R/B specify anthocyanin pigmentation in different plant tissues (6).…”