Genome Center of Wisconsin and Department of Horticulture, 1575 Linden Drive, University of Wisconsin-Madison, Madison, WI 53706, USA.
Plant J. 2010 Dec;64(6):990-1001. doi: 10.1111/j.1365-313X.2010.04386.x. Epub 2010 Nov 17.
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.
拟南芥 T-DNA 插入系的有序集合已成为植物科学家进行遗传研究的重要资源。先前的报告表明，T-DNA 插入系可能与 T-DNA 插入位点相关联的染色体易位，但这些重排的普遍性尚未得到很好的记录。为了确定在广泛使用的 T-DNA 插入系集合中易位出现的频率，我们分析了来自 Salk T-DNA 突变体集合的 64 个独立系。在所调查的 64 个系中的 12 个（19%）中检测到染色体易位。使用两种测定法筛选 T-DNA 系的易位：花粉活力和全基因组遗传作图。虽然花粉活力的测量是检测易位存在的间接筛选，但使用遗传作图分析时，所有 11 个表现出异常花粉表型的 T-DNA 系均被发现含有易位。然而，正常的花粉表型并不能保证不存在易位。我们观察到一个 T-DNA 系的花粉正常，但根据遗传作图结果仍存在易位。通过我们的遗传作图实验观察到的另一个现象是，在某些情况下，靶基因的 5'和 3'侧的 T-DNA 接头可以在遗传上彼此分离。我们调查的两条系中都显示了这种“T-DNA 边界分离”现象。本文介绍并讨论了用于有效筛选 T-DNA 系中染色体异常存在的实验程序。
