Cellular and gene expression patterns associated with root bifurcation in Selaginella
Cellular and gene expression patterns associated with root bifurcation in Selaginella
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DOI：
10.1101/2022.01.03.474808
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发表时间：
2022-01
期刊：
影响因子：
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通讯作者：
Tao Fang;Hans Motte;B. Parizot;Wouter Smet;Xilan Yang;L. Walker;M. Njo;G. Bassel;T. Beeckman
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文献类型：
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作者：
Tao Fang;Hans Motte;B. Parizot;Wouter Smet;Xilan Yang;L. Walker;M. Njo;G. Bassel;T. Beeckman
石松植物的根是通过二分或分叉进行分支的，即根尖分裂成两个子根。这在形态上不同于现存的真叶植物中的侧根（LR）分支，其中LR在距顶端不同的距离处沿沿着根轴发育。根分叉的过程知之甚少，但这些知识可能很重要，因为它可能代表了一种进化上古老的策略，即根招募形成新的干细胞或分生组织。在这项研究中，我们研究了石松卷柏的根分叉。我们的特点是在体外发育的时间框架的基础上重复的顶端分叉，使我们能够采样不同阶段的二叉根分支和分析的根分生组织和根分支在S。moellendorffii在显微镜和转录水平。我们的研究结果表明，与以前的假设相反，根分生组织中的初始细胞大多不是四面体，而是显示出不规则的形状。追踪早期阶段，在根分支主张发生对称分裂的单个初始细胞导致两个顶端干细胞允许根分生组织分叉。此外，我们还生成了一个S。moellendorffii根分支转录组，这导致了核心分生组织基因的子集的描绘。多个分生组织相关的直向同源物在这个数据集中的出现，包括SCARECROW（SCR）与视网膜母细胞瘤-RACTED 1（RBR 1）同源物的负相关的表达谱表明存在保守的途径控制分生组织和根干细胞的建立或维持。一句话总结穗藓卷柏的根分叉后，一个对称的细胞分裂的单个干细胞，并涉及保守的遗传模块已知的被子植物根。
The roots of lycophytes branch through dichotomy or bifurcation, which means that the root apex splits into two daughter roots. This is morphologically distinct from lateral root (LR) branching in the extant euphyllophytes, where LRs develop along the root axis at different distances from the apex. The process of root bifurcation is poorly understood, while such knowledge can be important, as it may represent an evolutionarily ancient strategy that roots recruited to form new stem cells or meristems. In this study, we examined root bifurcation in the lycophyte Selaginella moellendorffii. We characterized an in vitro developmental time-frame based on repetitive apex bifurcations, allowing us to sample different stages of dichotomous root branching and analyze the root meristem and root branching in S. moellendorffii at the microscopical and transcriptional level. Our results show that, in contrast to previous assumptions, initial cells in the root meristem are mostly not tetrahedral but rather show an irregular shape. Tracking down the early stages during root branching argues for the occurrence of a symmetric division of the single initial cell resulting in two apical stem cells allowing for root meristem bifurcation. Moreover, we generated a S. moellendorffii root branching transcriptome, which resulted in the delineation of a subset of core meristem genes. The occurrence of multiple meristem-related orthologues in this dataset, including inversely correlated expression profiles of a SCARECROW (SCR) versus a RETINOBLASTOMA-RELATED1 (RBR1) homologue suggests the presence of conserved pathways in the control of meristem and root stem cell establishment or maintenance. One-sentence summary The root of the spike moss Selaginella moellendorffii bifurcates following a symmetric cell division of the single stem cell and involves conserved genetic modules known from angiosperm roots.