Characterization of a highly conserved sequence related to mutator transposable elements in maize

Area of Science:

• Genetics
• Molecular Biology
• Plant Science

Background:

• Maize mutator stocks display high mutation rates linked to transposable element activity, primarily Mu1 and Mu1.7.
• These elements are abundant in mutator stocks but scarce in nonmutator lines.
• Component parts of Mu elements, like terminal inverted repeats and internal sequences, exist separately in the maize genome.

Purpose of the Study:

• To characterize the structure and genomic distribution of a Mu-homologous sequence, MRS-A.
• To investigate the evolutionary conservation and transcriptional activity of MRS-A.
• To explore the potential role of MRS-A in the generation of Mu transposable elements.

Main Methods:

• DNA sequencing to determine the structure of MRS-A.
• Genomic Southern analysis to assess the distribution of MRS-A in maize and related species.
• RNA analysis to detect transcripts homologous to MRS-A.

Main Results:

• MRS-A is homologous to the internal region of Mu1/Mu1.7 elements but lacks transposable element termini.
• MRS-A is present in one to two copies in all maize lines and is conserved across the genus Zea.
• A similar sequence exists in Tripsacum dactyloides, and MRS-A transcripts are detected in both mutator and nonmutator maize.

Conclusions:

• MRS-A represents a stable, functional maize genomic region.
• The high conservation and transcription suggest MRS-A is not a mere remnant but a significant genomic component.
• It is hypothesized that MRS-A, when associated with Mu termini, could form a functional Mu transposable element.