A site-specific insertion sequence in flax genotrophs induced by environment

Area of Science:

• Genetics
• Molecular Biology
• Plant Science

Background:

• Environmentally induced heritable changes in flax (Linum usitatissimum) lead to stable lines called genotrophs.
• Specific DNA alterations are associated with the formation of these genotrophs.

Purpose of the Study:

• To identify and characterize a specific DNA fragment involved in genotroph formation.
• To investigate the nature and occurrence of this DNA insertion in flax varieties.

Main Methods:

• Cloning and sequencing of the insertion sequence (LIS-1) and its flanking regions from genomic libraries.
• Polymerase Chain Reaction (PCR) amplification, cloning, and sequencing of insertion and surrounding DNA.
• Analysis of insertion site characteristics, including duplication and sequence alterations.

Main Results:

• A single-copy 5.7 kb DNA fragment, Linum Insertion Sequence 1 (LIS-1), was identified.
• LIS-1 insertion into a 3.7 kb EcoRI fragment in the plastic line (Pl) resulted in a 3 bp duplication and other sequence changes.
• The identical LIS-1 insertion was observed in other genotrophs and flax varieties, though the intact element was not found in Pl.
• LIS-1 appears to arise from a specific, complex insertion event during genotroph formation and is naturally present in many flax varieties.

Conclusions:

• LIS-1 represents a significant DNA change associated with environmentally induced heritable traits in flax.
• The insertion mechanism is targeted, highly specific, and complex, occurring during genotroph development.
• LIS-1 is a naturally occurring element in numerous flax and linseed varieties, indicating its broader relevance beyond induced genotrophs.