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".

大多数有性生殖的生物体都使用一种特殊的细胞分裂方式，称为减数分裂，这对产生遗传变异和配子中染色体数量减半非常重要。在减数分裂过程中，许多程序化的DNA双链断裂（DSB）形成，并通过减数分裂重组途径处理以形成交换，这是染色体之间相互交换遗传信息的点。杂交对于在每一代中创造新的遗传变异是必不可少的。了解植物减数分裂是一个很大的兴趣，因为驯化和强烈的选择性育种导致了农作物遗传变异的大量损失。继续对优良品种进行遗传改良以减轻气候变化的挑战，将需要通过形成杂交使野生品种的有益等位基因渐渗。不幸的是，交叉主要在染色体末端形成，占基因组的不到15%，而含有某些农业相关基因（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，了解影响杂交模式的因素，并制定策略来重新定位作物中的杂交品种是及时和必要的。在种属之间和个体内观察到DSB和交叉数的大量细胞变异。拟南芥和小麦花药中含有低重组和高重组减数分裂细胞的混合物，DSB和交换数高达70%。我们的前期研究表明，拟南芥中ASY1和HEI10的转录水平影响着交换的频率和位置。因此，我们认为性母细胞的重组结果受到几个基因表达的精细平衡的影响。因此，在转录组的异质性可能是负责的低和超重组性母细胞观察花药。然而，迄今为止，所有对植物减数分裂进行的基因组研究都包括细胞池，从而阻止了对导致这种变异的异质性因素的鉴定。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（T1在DSB形成期间，T2在交换形成期间）生成拟南芥性母细胞的单细胞转录组图谱，以了解从DSB形成到它们转化为交换的转录组动态。此外，我们将对转录高度相关的细胞进行分组，并使用来自已知基因的信息推断含有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换率）。然后，我们将使用这些数据来确定基因与重组异质性的假定作用。我们将补充这项研究的一组拟南芥过表达线的特点，找到基因影响重组的基础上，他们的转录水平。最后，我们将使用剂量敏感基因ASY1作为参考进行原理验证实验，以测试小麦中减数分裂基因表达的增加是否可以重新定位杂交，以有利于在常规育种中不易接近的区域进行重组。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新的途径，利用基因过表达来影响小麦的重组景观，这可能会为育种部门带来持久的利益。这项拟议的工作支持BBSRC的战略优先事项“前沿生物科学：了解生命规则”和“生物科学促进可持续农业和粮食”。