Department of Plant Sciences, University of Cambridge, Cambridge, UK.
Department of Life Sciences, Pohang University of Science and Technology, Pohang, Republic of Korea.
Nat Plants. 2021 Apr;7(4):452-467. doi: 10.1038/s41477-021-00889-y. Epub 2021 Apr 12.
Meiotic crossovers are tightly restricted in most eukaryotes, despite an excess of initiating DNA double-strand breaks. The majority of plant crossovers are dependent on class I interfering repair, with a minority formed via the class II pathway. Class II repair is limited by anti-recombination pathways; however, similar pathways repressing class I crossovers have not been identified. Here, we performed a forward genetic screen in Arabidopsis using fluorescent crossover reporters to identify mutants with increased or decreased recombination frequency. We identified HIGH CROSSOVER RATE1 (HCR1) as repressing crossovers and encoding PROTEIN PHOSPHATASE X1. Genome-wide analysis showed that hcr1 crossovers are increased in the distal chromosome arms. MLH1 foci significantly increase in hcr1 and crossover interference decreases, demonstrating an effect on class I repair. Consistently, yeast two-hybrid and in planta assays show interaction between HCR1 and class I proteins, including HEI10, PTD, MSH5 and MLH1. We propose that HCR1 plays a major role in opposition to pro-recombination kinases to restrict crossovers in Arabidopsis.
在大多数真核生物中，减数分裂交叉被严格限制，尽管有过量的起始 DNA 双链断裂。大多数植物交叉依赖于 I 类干扰修复，少数通过 II 类途径形成。II 类修复受到抗重组途径的限制；然而，尚未鉴定出抑制 I 类交叉的类似途径。在这里，我们使用荧光交叉报告基因在拟南芥中进行正向遗传筛选，以鉴定重组频率增加或减少的突变体。我们发现 HIGH CROSSOVER RATE1 (HCR1) 抑制交叉并编码蛋白磷酸酶 X1。全基因组分析表明 hcr1 交叉在远端染色体臂中增加。MLH1 焦点在 hcr1 中显著增加，交叉干扰减少，表明对 I 类修复有影响。一致地，酵母双杂交和体内测定表明 HCR1 与 I 类蛋白（包括 HEI10、PTD、MSH5 和 MLH1）之间存在相互作用。我们提出 HCR1 在拟南芥中发挥主要作用，以对抗促进重组的激酶来限制交叉。
