Developmental mechanisms that buffer mutational load in plants

项目摘要 多细胞生物由于细胞内的DNA损伤和错误而面临恒定的突变压力 师.新的突变在整个发育过程中不断积累，可能导致癌症， 衰老和不育随着通过深度测序检测突变的灵敏度增加， 很明显，即使是健康的个体也是遗传异质性的，并携带许多后- 体细胞和生殖细胞中的合子突变。该提案旨在了解如何 生物在发育过程中科普持续的突变，重点是玉米和拟南芥。第一、 我们将研究在整个生命周期中不同组织中突变的积累。遵循 新的突变，我们专注于转座子，因为它可以量化罕见的，最近的突变与高 灵敏度我们假设，发展是以一种保持多样性的方式组织起来的。 分生组织干细胞生态位，避免关键储库细胞中的群体瓶颈，从而防止 任何单一的体细胞突变都无法在整个生物体中固定下来。我们将测试植物是否 随着生长模式和分生组织缺陷的改变， 因为它们无法维持干细胞的多样性。其次，我们将研究染色体 玉米花粉发育过程中索马和胚系的调控。每粒花粉都是一个简单的 3-细胞生物，具有一个体细胞和两个生殖细胞。我们将研究 然后确定区分索马和种系表观遗传标记 建立和维护。将使用单细胞RNA-seq跟踪基因组变化， 染色质分析和显微镜检查。我们将使用一种新的方法来鉴定调节这一过程的基因。 直接在单倍体花粉中进行遗传筛选的策略，允许数百万的突变被 每株植物测定。最终，这项工作将深入了解生物体如何调节多细胞 发育和染色体结构，以减少新突变的影响。

Project Summary Multicellular organisms face constant mutational pressures due to DNA damage and errors in cell division. New mutations continually accumulate throughout development and can result in cancer, aging, and infertility. With the increased sensitivity to detect mutations by deep sequencing, it has become clear that even healthy individuals are genetically heterogeneous and carry numerous post- zygotic mutations in both their somatic and germinal cells. This proposal aims to understand how organisms cope with ongoing mutation during development, focusing on maize and Arabidopsis. First, we will investigate the accumulation of mutations in different tissues throughout the life cycle. To follow new mutations, we focus on transposons as it is possible to quantify rare, recent mutations with high sensitivity. We hypothesize that development is organized in a way that maintains the diversity of the meristem stem cell niche, avoiding population bottlenecks in critical reservoir cells and thus preventing any single somatic mutation from reaching fixation across the organism. We will test whether plants with altered growth patterns and meristem defects accumulate new mutations more frequently because they are unable to maintain stem cell diversity. Second, we will investigate chromosomal regulation in the soma and germline during maize pollen development. Each grain of pollen is a simple 3-celled organism, with a single somatic cell and two germ cells. We will study the activation of the haploid pollen genome and then determine how epigenetic marks that differentiate soma and germline are established and maintained. Genome changes will be followed using single-cell RNA-seq, chromatin profiling, and microscopy. We will identify genes that regulate this process using a novel strategy to perform genetic screens directly in haploid pollen, allowing millions of mutations to be assayed per plant. Ultimately, this work will shed insight into how organisms regulate multicellular development and chromosomal structure to reduce the impact of new mutations.