背景回顾：Long-lived plants face the challenge of ever-increasing mutational burden across their long lifespan. 

提出问题：Early sequestration of meristematic stem cells is supposed to efficiently slow down this process, but direct measurement of somatic mutations that accompanies segregated cell lineages in plants is still rare. 

主要研究：Here we tracked somatic mutations in 33 leaves and 22 adventitious roots from 22 stem-cuttings across eight major branches of a shrub willow (Salix suchowensis). 

结果1-叶v.s.根：We found that most mutations propagated separately in leaves and roots, providing clear evidence for early segregation of underlying cell lineages. 

结果2-叶：By combining lineage tracking with allele frequency analysis, our results revealed a set of mutations shared by distinct branches, but were exclusively present in leaves and not in roots. These mutations were likely propagated by rapidly dividing somatic cell lineages which survive several iterations of branching, distinct from the slowly dividing axillary stem cell lineages. Leaf is thus contributed by both slowly and rapidly dividing cell lineages, leading to varied fixation chances of propagated mutations.

结果3-根：By contrast, each root likely arises from a single founder cell within the adventitious stem cell lineages.

结论：Our findings give straightforward evidence that early segregation of meristems slows down mutation accumulation in axillary meristems, implying a plant “germline” paralogue to the germline of animals through convergent evolution.

 摘 要 

长寿植物在其漫长的生命周期中需要面对不断增加的突变负担的挑战。分生组织干细胞的早期“分隔”被认为可以有效地减缓这一过程，但直接测量伴随着分隔的细胞系的体细胞突变在植物中还是很少见。本文中，作者追踪了簸箕柳（一种灌木状柳树）8个主要枝条上22个茎插条的33片叶子和22个不定根的体细胞突变。作者发现，大多数的突变在叶和根中分别传播，这些证据表明基础细胞谱系在早期就已经分隔。通过结合谱系追踪和等位基因频率分析，作者鉴定到了一小群由不同分枝所共同拥有的一些突变，这些突变只在叶中有，而根中没有。这些突变很可能是通过快速分裂的体细胞谱系进行传播，并在多次分枝后保存下来，区别于分裂较慢的腋生干细胞谱系。因此，叶片是由缓慢和快速分裂的细胞谱系共同作用的，从而导致传播的突变存在不同固定机会。相反，每一个根很有可能是起始于不定干细胞系中的单个建成细胞。本文的发现直接表明了分生组织的早期分隔减缓了腋生分生组织中的突变积累，揭示了植物通过趋同演化获得了一种类似于动物生殖系的策略。