Singer Kamy, Lee Lan-Ying, Yuan Jing, Gelvin Stanton B
Department of Biological Sciences, Purdue University, West Lafayette, IN, United States.
Front Plant Sci. 2022 May 6;13:849930. doi: 10.3389/fpls.2022.849930. eCollection 2022.
transfers T-DNA to plants where it may integrate into the genome. Non-homologous end-joining (NHEJ) has been invoked as the mechanism of T-DNA integration, but the role of various NHEJ proteins remains controversial. Genetic evidence for the role of NHEJ in T-DNA integration has yielded conflicting results. We propose to investigate the formation of T-circles as a proxy for understanding T-DNA integration. T-circles are circular double-strand T-DNA molecules, joined at their left (LB) and right (RB) border regions, formed in plants. We characterized LB-RB junction regions from hundreds of T-circles formed in or . These junctions resembled T-DNA/plant DNA junctions found in integrated T-DNA: Among complex T-circles composed of multiple T-DNA molecules, RB-RB/LB-LB junctions predominated over RB-LB junctions; deletions at the LB were more frequent and extensive than those at the RB; microhomology was frequently used at junction sites; and filler DNA, from the plant genome or various replicons, was often present between the borders. Ku80 was not required for efficient T-circle formation, and a VirD2 mutation affected T-circle formation and T-DNA integration similarly. We suggest that investigating the formation of T-circles may serve as a surrogate for understanding T-DNA integration.
它将T-DNA转移至植物中，并可能整合到基因组中。非同源末端连接（NHEJ）被认为是T-DNA整合的机制，但各种NHEJ蛋白的作用仍存在争议。关于NHEJ在T-DNA整合中作用的遗传证据产生了相互矛盾的结果。我们建议研究T环的形成，以此作为理解T-DNA整合的替代方法。T环是在植物中形成的环状双链T-DNA分子，在其左（LB）和右（RB）边界区域相连。我们对在[具体植物1]或[具体植物2]中形成的数百个T环的LB-RB连接区域进行了表征。这些连接类似于整合的T-DNA中发现的T-DNA/植物DNA连接：在由多个T-DNA分子组成的复杂T环中，RB-RB/LB-LB连接比RB-LB连接占主导；LB处的缺失比RB处更频繁且更广泛；连接位点经常使用微同源性；并且在边界之间经常存在来自植物基因组或各种[具体复制子]复制子的填充DNA。高效形成T环不需要Ku80，并且VirD2[具体突变]对T环形成和T-DNA整合的影响类似。我们认为研究T环的形成可作为理解T-DNA整合的替代方法。
