PDF(Pubmed)
Abstract：
BACKGROUND: Plant meristems are structured organs consisting of distinct layers of stem cells, which differentiate into new plant tissue. Mutations in meristematic layers can propagate into large sectors of the plant. However, the characteristics of meristematic mutations remain unclear, limiting our understanding of the genetic basis of somaclonal phenotypic variation.
RESULTS: Here, we analyse the frequency and distribution of somatic mutations in an apricot tree. We separately sequence the epidermis (developing from meristem layer 1) and the flesh (developing from meristem layer 2) of several fruits sampled across the entire tree. We find that most somatic mutations (> 90%) are specific to individual layers. Interestingly, layer 1 shows a higher mutation load than layer 2, implying different mutational dynamics between the layers. The distribution of somatic mutations follows the branching of the tree. This suggests that somatic mutations are propagated to developing branches through axillary meristems. In turn, this leads us to the unexpected observation that the genomes of layer 1 of distant branches are more similar to each other than to the genomes of layer 2 of the same branches. Finally, using single-cell RNA sequencing, we demonstrate that layer-specific mutations were only transcribed in the cells of the respective layers and can form the genetic basis of somaclonal phenotypic variation.
CONCLUSIONS: Here, we analyse the frequency and distribution of somatic mutations with meristematic origin. Our observations on the layer specificity of somatic mutations outline how they are distributed, how they propagate, and how they can impact clonally propagated crops.
RESULTS: Here, we analyse the frequency and distribution of somatic mutations in an apricot tree. We separately sequence the epidermis (developing from meristem layer 1) and the flesh (developing from meristem layer 2) of several fruits sampled across the entire tree. We find that most somatic mutations (> 90%) are specific to individual layers. Interestingly, layer 1 shows a higher mutation load than layer 2, implying different mutational dynamics between the layers. The distribution of somatic mutations follows the branching of the tree. This suggests that somatic mutations are propagated to developing branches through axillary meristems. In turn, this leads us to the unexpected observation that the genomes of layer 1 of distant branches are more similar to each other than to the genomes of layer 2 of the same branches. Finally, using single-cell RNA sequencing, we demonstrate that layer-specific mutations were only transcribed in the cells of the respective layers and can form the genetic basis of somaclonal phenotypic variation.
CONCLUSIONS: Here, we analyse the frequency and distribution of somatic mutations with meristematic origin. Our observations on the layer specificity of somatic mutations outline how they are distributed, how they propagate, and how they can impact clonally propagated crops.
摘要：
背景：植物分生组织是由不同的干细胞层组成的结构化器官，分化为新的植物组织。分生组织层中的突变可以传播到植物的大部分。然而,分生组织突变的特征仍不清楚，限制了我们对体细胞克隆表型变异的遗传基础的理解。
结果：这里，我们分析了杏树体细胞突变的频率和分布。我们分别对整个树上采样的几种果实的表皮（从分生组织层1发育）和果肉（从分生组织层2发育）进行测序。我们发现大多数体细胞突变（>90％）是个体层特有的。有趣的是,层1显示比层2更高的突变负荷，这意味着层之间的突变动力学不同。体细胞突变的分布遵循树的分支。这表明体细胞突变通过腋生分生组织传播到发育中的分支。反过来,这导致了我们意想不到的观察，即远处分支的第1层的基因组比相同分支的第2层的基因组更相似。最后,使用单细胞RNA测序，我们证明，层特异性突变仅在相应层的细胞中转录，并且可以形成体细胞克隆表型变异的遗传基础。
结论：这里，我们分析了分生组织起源的体细胞突变的频率和分布。我们对体细胞突变的层特异性的观察概述了它们是如何分布的，它们是如何传播的，以及它们如何影响克隆繁殖的作物。
结果：这里，我们分析了杏树体细胞突变的频率和分布。我们分别对整个树上采样的几种果实的表皮（从分生组织层1发育）和果肉（从分生组织层2发育）进行测序。我们发现大多数体细胞突变（>90％）是个体层特有的。有趣的是,层1显示比层2更高的突变负荷，这意味着层之间的突变动力学不同。体细胞突变的分布遵循树的分支。这表明体细胞突变通过腋生分生组织传播到发育中的分支。反过来,这导致了我们意想不到的观察，即远处分支的第1层的基因组比相同分支的第2层的基因组更相似。最后,使用单细胞RNA测序，我们证明，层特异性突变仅在相应层的细胞中转录，并且可以形成体细胞克隆表型变异的遗传基础。
结论：这里，我们分析了分生组织起源的体细胞突变的频率和分布。我们对体细胞突变的层特异性的观察概述了它们是如何分布的，它们是如何传播的，以及它们如何影响克隆繁殖的作物。
