The Plant Journal:华南农大胡宇飞研究组发布T-DNA整合机制的重要证
2017年2月28日，国际植物学权威期刊《The plant Journal》在线发表了华南农业大学生命科学学院胡宇飞研究员和黄吉雷研究员的一篇研究论文，论文发表了关于T-DNA整合与DNA断裂修复机制之间关联的重要证据。论文题为“Cascade of chromosomal rearrangements caused by a heterogeneous T-DNA integration supports the double-strand break repair model for T-DNA integration”。生命科学学院教师胡宇飞为第一作者及共同通讯作者，学校测试中心黄吉雷为共同通讯作者。
农杆菌介导的T-DNA整合是实现植物转基因的基础，但T-DNA如何整合到植物宿主基因组的机制并不清楚。该论文首次在拟南芥中发现并证实了T-DNA分子的两个末端可以整合到染色体不同断裂点(DSB)中，并将此现象称之为heteroGENEous T-DNA 整合，该现象充分说明DSB修复机制在T-DNA整合过程中发挥重要作用。在heterogeneous T-DNA整合发生时，T-DNA两个末端的独立整合行为引发植物基因组集中出现级联的错误DSB修复，最终导致所有常见染色体畸变，包括移位、倒位、重复和缺失。广泛出现的DNA错误修复暗示农杆菌侵染对植物内源DSB修复机制具有劫持的可能。
原文链接：
Cascade of chromosomal rearrangements caused by a heterogeneous T-DNA integration supports the double-strand break repair model for T-DNA integration
原文摘要：
Transferred DNA (T-DNA) from Agrobacterium tumefaciens can be integrated into the plant genome. The double-strand break repair (DSBR) pathway is a major model for T-DNA integration. From this model, we expect that two ends of a T-DNA molecule would invade into a single DNA double-strand break (DSB) or independent DSBs in the plant genome. We call the later phenomenon a heterogeneous T-DNA integration which has never been observed. In this work, we demonstrated it in an Arabidopsis T-DNA insertion mutant seb19. To resolve the chromosomal structural changes caused by T-DNA integration at both the nucleotide and chromosome levels, we performed inverse PCR, genome resequencing, fluorescence in situ hybridization and linkage analysis. We found, in seb19, a single T-DNA connected two different chromosomal loci and caused complex chromosomal rearrangements. The specific break-junction pattern in seb19 is consistent with the result of heterogeneous T-DNA integration but not of recombination between two T-DNA insertions. We demonstrated that, in seb19, heterogeneous T-DNA integration evoked a cascade of incorrect repair of seven DSBs on chromosome 4 and 5, and then produced translocation, inversion, duplication and deletion. Heterogeneous T-DNA integration supports the DSBR model and suggests that two ends of a T-DNA molecule could be integrated into the plant genome independently. Our results also show a new origin of chromosomal abnormalities.
作者：胡宇飞
