Department of Biology, East China Normal University, 3663 North Zhong Shan Road, Shanghai 200062, China.
Plant J. 2012 Oct;72(2):271-81. doi: 10.1111/j.1365-313X.2012.05075.x. Epub 2012 Jul 26.
DNA double-strand break (DSB) formation is the initial event for meiotic recombination catalyzed by the conserved Spo11 protein. In Arabidopsis, several proteins have been reported to be involved in DSB formation. Here, we report an Arabidopsis DSB forming (DFO) gene in Arabidopsis that is involved in DSB formation. The dfo mutant exhibits reduced fertility, producing polyads with an abnormal number of microspores, unlike the tetrads in the wild type. The dfo meiocytes were defective in homologous chromosome synapsis and segregation. Genetic analysis revealed that the homologous recombination of Atdfo-1 is severely affected in meiotic prophase I. DFO encodes a protein without any known conserved domain. There was no homologue identified outside the plant kingdom, indicating that AtDFO is a plant-specific protein. AtMRE11 has been reported to be responsible for processing SPO11-generated DSBs. The Atmre11 mutant displays chromosome fragmentation during meiosis. However, the Atdfo Atmre11 double mutant had no such chromosome fragmentation, indicating that AtDFO is required for DSB formation.
DNA 双链断裂（DSB）的形成是由保守的 Spo11 蛋白催化的减数分裂重组的初始事件。在拟南芥中，已经报道了几种参与 DSB 形成的蛋白质。在这里，我们在拟南芥中报告了一个参与 DSB 形成的拟南芥 DSB 形成（DFO）基因。dfo 突变体表现出降低的育性，产生具有异常微孢子数目的多联体，与野生型中的四分体不同。dfo 减数分裂细胞在同源染色体联会和分离中存在缺陷。遗传分析表明，dfo-1 的同源重组在减数分裂前期 I 中受到严重影响。DFO 编码一种没有任何已知保守结构域的蛋白质。在植物界之外没有鉴定出同源物，表明 AtDFO 是一种植物特异性蛋白。AtMRE11 已被报道负责处理 SPO11 产生的 DSB。Atmre11 突变体在减数分裂过程中表现出染色体碎片化。然而，Atdfo Atmre11 双突变体没有这种染色体碎片化，表明 AtDFO 是 DSB 形成所必需的。
