Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466 Gatersleben, Germany.
Plant J. 2011 Oct;68(1):28-39. doi: 10.1111/j.1365-313X.2011.04662.x. Epub 2011 Jul 11.
Minichromosomes possess functional centromeres and telomeres and thus should be stably inherited. They offer an enormous opportunity to plant biotechnology as they have the potential to simultaneously transfer and stably express multiple genes. Segregating independently of host chromosomes, they provide a platform for accelerating plant breeding. Following a top-down approach, we truncated endogenous chromosomes in Arabidopsis thaliana by Agrobacterium-mediated transfer of T-DNA constructs containing telomere sequences. Blocks of A. thaliana telomeric repeats were inserted into a binary vector suitable for stable transformation. After transfer of these constructs into the natural tetraploid A. thaliana accession Wa-1, chromosome truncation by T-DNA-induced de novo formation of telomeres could be confirmed by DNA gel blot analysis, PCR (polymerase chain reaction), and fluorescence in situ hybridisation. The addition of new telomere repeats in this process could start alternatively from within the T-DNA-derived telomere repeats or from adjacent sequences close to the right border of the T-DNA. Truncated chromosomes were transmissible in sexual reproduction, but were inherited at rates lower than expected according to Mendelian rules.
微染色体具有功能的着丝粒和端粒，因此应该能够稳定遗传。它们为植物生物技术提供了巨大的机会，因为它们有可能同时转移和稳定表达多个基因。微染色体与宿主染色体独立分离，为加速植物育种提供了一个平台。我们采用自上而下的方法，通过农杆菌介导的含有端粒序列的 T-DNA 构建体转移，在拟南芥中截断内源性染色体。将 A. thaliana 的端粒重复序列块插入适合稳定转化的二元载体中。将这些构建体转移到天然四倍体 A. thaliana 品系 Wa-1 中后，通过 T-DNA 诱导从头形成端粒的 DNA 凝胶印迹分析、PCR（聚合酶链反应）和荧光原位杂交，可以证实 T-DNA 诱导的染色体截断。在这个过程中，新的端粒重复序列可以从 T-DNA 衍生的端粒重复序列内部或靠近 T-DNA 右边界的邻近序列开始添加。截断的染色体在有性繁殖中是可传递的，但遗传率低于孟德尔法则所预期的。
