Unravelling the meiotic single-cell transcriptomic atlas for the control of recombination.

揭示减数分裂单细胞转录组图谱以控制重组。

• 批准号: BB/Y001591/1
• 负责人: Christophe Lambing
• 金额: $ 82.45万
• 依托单位: Rothamsted Research
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FY001591%2F1
• 关键词: Unravelling; meiotic; single; cell; transcriptomic

Most organisms that reproduce sexually use a special type of cell division, called meiosis, that is important for the creation of genetic variation and halving the chromosome numbers in gametes. During meiosis, numerous programmed DNA double strand-breaks (DSBs) are formed and processed by the meiotic recombination pathway to form crossovers, which are the points of reciprocal exchange of genetic information between chromosomes. Crossovers are essential to create novel genetic variation in each generation. There is a major interest to understand meiosis in plants because domestication and intense selective breeding have led to a substantial loss of genetic variation in crops. Continued genetic improvement of elite cultivars to mitigate the challenge of climate change will require the introgression of beneficial alleles from wild varieties through the formation of crossovers. Unfortunately, crossovers are mainly formed at the end of the chromosomes, representing less than 15% of the genome, whereas more centric regions, which contain certain genes of agricultural relevance, like defence response genes, rarely recombine in most major crops. Therefore, it is both timely and imperative to understand the factors influencing crossover patterning and to create strategies to reposition crossovers in crops. Substantial cellular variation in DSB and crossover numbers is observed between species and within individuals. Arabidopsis and wheat anthers contain a mixture of hypo- and hyper-recombinant meiotic cells varying in DSB and crossover numbers by up to 70%. Our previous studies revealed that the frequency and position of the crossovers are influenced by the transcript levels of ASY1 and HEI10 in Arabidopsis. Therefore, we propose that the recombination outcome of a meiocyte is influenced by a fine balance of expression of several genes. Hence, heterogeneity in the transcriptome could be responsible for the hypo- and hyper-recombination meiocytes observed in anthers. However, all genomic studies carried out on plant meiosis have so far included pools of cells, thus preventing the identification of heterogeneous factors responsible for such variation. In this project, we propose to generate a single cell transcriptomic atlas of Arabidopsis meiocytes at two key time points of meiotic recombination (T1 during DSB formation, T2 during crossover formation) to understand the transcriptome dynamics from the formation of DSBs to their conversion into crossovers. In addition, we will group cells that are transcriptionally highly correlated and infer the cluster of cells that contains the hyper-recombinant meiocytes using information from known genes (e.g. higher HEI10 transcript level corresponds to higher crossover rate). We will then use this data to identify genes with a putative role in recombination heterogeneity. We will complement this study with the characterisation of a set of Arabidopsis over-expressing lines to find genes influencing recombination based on their transcript level. Lastly, we will perform a proof-of-principle experiment, using the dosage-sensitive gene ASY1 as a reference, to test if increasing meiotic gene expression in wheat could reposition crossovers to favour recombination in regions which are not easily accessible in conventional breeding. These new data will provide impact through the use of innovative approaches to understand the inter-relationship between transcriptome and recombination heterogeneity, decipher the transcriptome dynamics during meiosis and discover genes involved in meiosis. This project also aims to explore a novel route for impact in wheat using gene over-expression to influence the recombination landscape, which could confer lasting benefits for the breading sector. This proposed work supports BBSRC strategic priorities "Frontier bioscience: understanding the rules of life" and "Bioscience for sustainable agriculture and food".

大多数重现性使用特殊类型的细胞分裂的生物（称为减数分裂），这对于产生遗传变异和使配子中的染色体数量减半很重要。在减数分裂过程中，由减数分裂重组途径形成并处理了许多编程的DNA双链破裂（DSB），以形成交叉，这是染色体之间遗传信息的相互交换的点。跨界对于在每一代中创造新的遗传变异至关重要。了解植物中的减数分裂是一个主要的兴趣，因为驯化和强烈的选择性育种导致农作物遗传变异大大丧失。精英品种持续的遗传改善以减轻气候变化的挑战将需要通过跨界形成从野生品种中渗入有益等位基因。不幸的是，交叉主要在染色体的末端形成，不到基因组的15％，而含有某些农业相关性基因的中心区域（例如国防反应基因）在大多数主要的主要农作物中很少重新组合。因此，了解影响交叉模式的因素并创建在农作物中重新定位跨界的策略既及时又必须进行。在物种和个体内部观察到DSB的大量细胞变异和交叉数量。拟南芥和小麦花药含有多种多样的减数分裂细胞在DSB中变化，交叉数量的混合物高达70％。我们先前的研究表明，跨界的频率和位置受拟南芥中ASY1和HEI10的转录水平的影响。因此，我们提出，限量细胞的重组结果受几种基​​因表达的良好平衡的影响。因此，转录组中的异质性可能是导致在花药中观察到的低组化和过度重组的减数量的原因。但是，到目前为止，所有关于植物减数分裂的基因组研究都包括细胞池，从而阻止了导致这种变异的异质因素的鉴定。在这个项目中，我们建议在减数分裂重组的两个关键时间点（DSB形成期间的T1，T2在交叉形成过程中）生成一个单细胞转录图，以了解从DSB的形成到交叉转换的转录组动力学。此外，我们将使用来自已知基因的信息（例如，较高的HEI10转录物水平对应于较高的交叉率），将在转录高度相关的细胞分组，并推断包含超重组细胞的细胞簇。然后，我们将使用这些数据来识别在重组异质性中具有推定作用的基因。我们将通过一组拟南芥过表达的线的表征来补充这项研究，以根据其转录水平找到影响重组的基因。最后，我们将使用对剂量敏感的基因ASY1进行原则证明实验，以测试小麦中增加的减数分裂基因表达是否可以重新放置交叉以有利于在常规育种中不容易获得的区域中重新组合。这些新数据将通过使用创新方法来理解转录组和重组异质性之间的相互关系，破译减数分裂过程中的转录组动力学并发现与减数分裂有关的基因。该项目还旨在探索使用基因过表达来影响重组景观的新型小麦影响途径，这可能会给面包屑带来持久的好处。这项拟议的工作支持BBSRC战略重点“边境生物科学：了解生命规则”和“可持续农业和食品的生物科学”。