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".

大多数有性繁殖的生物体都使用一种特殊类型的细胞分裂，称为减数分裂，这对于遗传变异的产生和配子中染色体数量减半非常重要。在减数分裂过程中，形成许多程序化的DNA双链断裂（DSB），并通过减数分裂重组途径进行处理以形成交叉，这是染色体之间遗传信息相互交换的点。交叉对于在每一代中创造新的遗传变异至关重要。人们对了解植物减数分裂非常感兴趣，因为驯化和强烈的选择性育种已导致作物遗传变异的大量丧失。继续对优良品种进行遗传改良以减轻气候变化的挑战将需要通过形成交叉从野生品种中引入有益等位基因。不幸的是，交叉主要形成于染色体末端，占基因组的不到 15%，而包含某些与农业相关的基因（如防御反应基因）的中心区域很少在大多数主要作物中重组。因此，了解影响交叉模式的因素并制定重新定位作物交叉的策略是及时且必要的。在物种之间和个体内部观察到 DSB 和交叉数的显着细胞差异。拟南芥和小麦花药含有低重组和高重组减数分裂细胞的混合物，其 DSB 和交叉数差异高达 70%。我们之前的研究表明，拟南芥中交换的频率和位置受ASY1和HEI10转录水平的影响。因此，我们认为性母细胞的重组结果受到多个基因表达的精细平衡的影响。因此，转录组的异质性可能是花药中观察到的性母细胞低重组和高重组的原因。然而，迄今为止，对植物减数分裂进行的所有基因组研究都包括细胞池，因此无法识别导致这种变异的异质因素。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，交叉形成期间的T2）生成拟南芥性母细胞的单细胞转录组图谱，以了解从DSB形成到转化为交叉的转录组动态。此外，我们将对转录高度相关的细胞进行分组，并使用已知基因的信息推断包含超重组性母细胞的细胞簇（例如，较高的 HEI10 转录水平对应于较高的交叉率）。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系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，我们将进行原理验证实验，使用剂量敏感基因 ASY1 作为参考，测试增加小麦减数分裂基因表达是否可以重新定位交叉，以有利于传统育种中不易进入的区域进行重组。这些新数据将通过使用创新方法来了解转录组和重组异质性之间的相互关系，破译减数分裂期间的转录组动态并发现参与减数分裂的基因，从而产生影响。该项目还旨在探索一种利用基因过度表达来影响重组景观的小麦影响新途径，这可以为面包行业带来持久的利益。这项拟议的工作支持 BBSRC 的战略重点“前沿生物科学：了解生命规则”和“可持续农业和食品的生物科学”。