Chromosomal translocations are a common phenomenon in Arabidopsis thaliana T‐DNA insertion lines
2010
Clark, Katie A. | Krysan, Patrick J.
Ordered collections of Arabidopsis thaliana lines containing mapped T‐DNA insertions have become an important resource for plant scientists performing genetic studies. Previous reports have indicated that T‐DNA insertion lines can have chromosomal translocations associated with the T‐DNA insertion site, but the prevalence of these rearrangements has not been well documented. To determine the frequency with which translocations are present in a widely‐used collection of T‐DNA insertion lines, we analyzed 64 independent lines from the Salk T‐DNA mutant collection. Chromosomal translocations were detected in 12 of the 64 lines surveyed (19%). Two assays were used to screen the T‐DNA lines for translocations: pollen viability and genome‐wide genetic mapping. Although the measurement of pollen viability is an indirect screen for the presence of a translocation, all 11 of the T‐DNA lines showing an abnormal pollen phenotype were found to contain a translocation when analyzed using genetic mapping. A normal pollen phenotype does not, however, guarantee the absence of a translocation. We observed one T‐DNA line with normal pollen that nevertheless had a translocation based on genetic mapping results. One additional phenomenon that we observed through our genetic mapping experiments was that the T‐DNA junctions on the 5′‐ and 3′‐sides of a targeted gene can genetically separate from each other in some cases. Two of the lines in our survey displayed this ‘T‐DNA borders separate' phenomenon. Experimental procedures for efficiently screening T‐DNA lines for the presence of chromosomal abnormalities are presented and discussed.
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