Instituto de Biología, Universidad de Antioquia, Medellín, Colombia.
Centro Nacional de Secuenciación Genómica (CNSG), Sede de Investigación Universitaria, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia.
Ann Bot. 2021 May 7;127(6):749-764. doi: 10.1093/aob/mcab033.
The epidermis constitutes the outermost tissue of the plant body. Although it plays major structural, physiological and ecological roles in embryophytes, the molecular mechanisms controlling epidermal cell fate, differentiation and trichome development have been scarcely studied across angiosperms, and remain almost unexplored in floral organs.
In this study, we assess the spatio-temporal expression patterns of GL2, GL3, TTG1, TRY, MYB5, MYB6, HDG2, MYB106-like, WIN1 and RAV1-like homologues in the magnoliid Aristolochia fimbriata (Aristolochiaceae) by using comparative RNA-sequencing and in situ hybridization assays.
Genes involved in Aristolochia fimbriata trichome development vary depending on the organ where they are formed. Stem, leaf and pedicel trichomes recruit most of the transcription factors (TFs) described above. Conversely, floral trichomes only use a small subset of genes including AfimGL2, AfimRAV1-like, AfimWIN1, AfimMYB106-like and AfimHDG2. The remaining TFs, AfimTTG1, AfimGL3, AfimTRY, AfimMYB5 and AfimMYB6, are restricted to the abaxial (outer) and the adaxial (inner) pavement epidermal cells.
We re-evaluate the core genetic network shaping trichome fate in flowers of an early-divergent angiosperm lineage and show a morphologically diverse output with a simpler genetic mechanism in place when compared to the models Arabidopsis thaliana and Cucumis sativus. In turn, our results strongly suggest that the canonical trichome gene expression appears to be more conserved in vegetative than in floral tissues across angiosperms.
表皮是植物体的最外层组织。尽管它在胚胎植物中发挥着主要的结构、生理和生态作用，但控制表皮细胞命运、分化和毛状体发育的分子机制在被子植物中研究甚少，在花器官中几乎未被探索。
在这项研究中，我们通过比较 RNA 测序和原位杂交试验，评估了在木兰类植物马兜铃科马兜铃属（Aristolochia fimbriata）中 GL2、GL3、TTG1、TRY、MYB5、MYB6、HDG2、MYB106 类、WIN1 和 RAV1 类同源物的时空表达模式。
参与马兜铃属毛状体发育的基因因形成器官而异。茎、叶和花梗毛状体募集了上述大部分转录因子（TFs）。相反，花毛状体仅使用一小部分基因，包括 AfimGL2、AfimRAV1-like、AfimWIN1、AfimMYB106-like 和 AfimHDG2。其余的 TFs，AfimTTG1、AfimGL3、AfimTRY、AfimMYB5 和 AfimMYB6，仅局限于背侧（外）和腹侧（内）的扁平表皮细胞。
我们重新评估了形成花毛状体命运的核心遗传网络，并展示了一个形态多样的输出，与拟南芥和黄瓜的模型相比，其遗传机制更为简单。反过来，我们的结果强烈表明，在被子植物中，经典毛状体基因表达在营养组织中比在花组织中更为保守。
