Developmental mechanisms that buffer mutational load in plants

项目摘要 由于DNA损伤和细胞内的错误，多细胞生物面临着持续的突变压力 组织。新的突变在整个发育过程中不断积累，并可能导致癌症， 衰老和不孕不育。随着通过深度测序检测突变的灵敏度增加，它已经 越来越清楚的是，即使健康的人也是遗传异质性的，并携带大量的后遗症 他们的体细胞和生发细胞中都存在合子突变。这项提案旨在了解如何 有机体在发育过程中应对持续的突变，重点是玉米和拟南芥。第一, 我们将研究突变在整个生命周期中在不同组织中的积累。追随 新的突变，我们专注于转座子，因为它可以量化罕见的，最近的高突变 敏感度。我们假设发展是以一种保持多样性的方式组织的 分生组织干细胞生态位，避免了关键储藏细胞的种群瓶颈，从而防止了 任何单一的体细胞突变都不会在整个生物体内达到固定。我们将测试植物是否 随着生长模式的改变和分生组织的缺陷，更频繁地积累新的突变 因为他们无法维持干细胞的多样性。第二，我们将研究染色体 玉米花粉发育过程中胞体和种系的调控。每粒花粉都是一粒简单的 3细胞生物体，有一个体细胞和两个生殖细胞。我们将研究如何激活 单倍体花粉基因组，然后确定表观遗传标记如何区分体细胞和种系 都是建立和维护的。基因组变化将使用单细胞RNA-SEQ进行跟踪， 染色质分析和显微镜检查。我们将使用一种新的方法来识别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，允许数百万个突变 每株进行化验。最终，这项工作将深入了解生物体如何调节多细胞 减少新突变对发育和染色体结构的影响。

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.