Transposable element Mu1 is found in multiple copies only in Robertson's Mutator maize lines

Area of Science:

• Molecular Biology
• Genetics
• Plant Science

Background:

• The Robertson's Mutator system in maize is associated with genetic instability.
• Understanding the genetic elements responsible for this instability is crucial for maize genetics.

Purpose of the Study:

• To clone and characterize the DNA fragment responsible for mutations in Robertson's Mutator maize.
• To determine if this element is a transposable element and assess its genomic distribution.

Main Methods:

• Cloning of a 1.4 kb DNA fragment (Mu1) from the Adh1 locus of maize.
• Analysis of DNA hybridization patterns and genomic distribution in various maize lines and relatives.

Main Results:

• The cloned 1.4 kb DNA fragment, designated Mu1, was identified as a transposable element due to its characteristics, including terminal inverted repeats and induced mutation instability.
• Mu1-like elements are present in 10-70 copies per diploid genome in all Robertson's Mutator corn lines.
• These elements exhibit high mobility, appearing on different genomic restriction fragments in closely related individuals.
• No strongly cross-hybridizing DNA was detected in non-Mutator maize lines or their relatives.

Conclusions:

• The Mu1 element is a transposable element responsible for mutations in the Robertson's Mutator system of maize.
• The presence and high mobility of Mu1-like elements are characteristic of Robertson's Mutator maize.
• Mu1 represents a distinct genetic element not found in other tested maize varieties or relatives.