Submitted to: Maize Genetics Cooperation Newsletter
Publication Type: Research Notes
Publication Acceptance Date: 3/11/1999
Publication Date: N/A
Interpretive Summary: Transposable elements (TE) are segments of DNA that move from one location to another within a plant's chromosomes. The movement of these elements is very important. Alterations to the message established by DNA sequence can occur due to these relocation events. Therefore, it is important to identify and characterize TEs when they are discovered. This report describes the identification of two new TEs from maize, which belong to a family of TEs called CACTA elements. The general DNA structure of these TEs is given.
Technical Abstract: Transposable element (TE) specific features are terminal inverted repeats and a target site duplication upon integration. Elements containing identical inverted repeats have been grouped into families. The characteristics of the CACTA family are the CACTA terminal inverted repeats and a 3 bp target site duplication. We have found two further such elements in maize through the molecular analysis of anthocyanin genes. These new CACTA elements have been identified through the analysis of the In (Intensifier) gene and the C2 (Chalcone synthase) mutant C2-Idf (Inhibitor diffuse). In Intron 6 of In a 948 bp long CACTA element and a 3 bp target site duplication have been identified by comparing the sequences of the alleles In and In-D (Intensifier dilute). The highly repetitive element contains several direct and indirect repeats, and palindromic sequences. The analysis of this transposable element showed a region of 450 bp with a high AT content (69%). Polyadenylated homologous transcripts of this element have been found in young seedlings, roots, embryos and tassels. Six such transcripts were isolated from a cDNA library and sequenced. The sequences are highly conserved (78-88%) and vary between 109 bp and 153 bp in length. Part of the CACTA element (about 500 bp) is also inserted in the C2, Whp, and C1 genes. So far, no regulatory function of this element could be detected. Upon sequence analysis of the C2-Idf allele another member of the CACTA element family was discovered. It is integrated into the promoter of one of the three known "C2 copies" present in the mutant C2-Idf. This element is 1165 bp in length.