Dries Eloise, Meyers Yannick, Liesner Daniel, Gonzaga Floriele M, Becker Jakob F M, Zakka Eliane E, Beeckman Tom, Coelho Susana M, De Clerck Olivier, Bogaert Kenny A
Phycology Research Group, Department of Biology, Ghent University, Krijgslaan 281 S8, Ghent, B-9000, Belgium.
Laboratory of Cell and Developmental Biology, Wageningen University & Research, Droevendaalsesteeg 1, Wageningen, 6708 PB, the Netherlands.
New Phytol. 2024 Sep;243(5):1887-1898. doi: 10.1111/nph.19953. Epub 2024 Jul 10.
The role of maternal tissue in embryogenesis remains enigmatic in many complex organisms. Here, we investigate the contribution of maternal tissue to apical-basal patterning in the kelp embryo. Focussing on Undaria pinnatifida, we studied the effects of detachment from the maternal tissue using microsurgery, staining of cell wall modifications, morphometric measurements, flow cytometry, genotyping and a modified kelp fertilisation protocol synchronising kelp embryogenesis. Detached embryos are rounder and often show aberrant morphologies. When a part of the oogonial cell wall remains attached to the zygote, the apical-basal patterning is rescued. Furthermore, the absence of contact with maternal tissue increases parthenogenesis, highlighting the critical role of maternal signals in the initial stages of development. These results show a key role for the connection to the maternal oogonial cell wall in apical-basal patterning in kelps. This observation is reminiscent of another brown alga, Fucus, where the cell wall directs the cell fate. Our findings suggest a conserved mechanism across phylogenetically distant oogamous lineages, where localised secretion of sulphated F2 fucans mediates the establishment of the apical-basal polarity. In this model, the maternal oogonial cell wall mediates basal cell fate determination by providing an extrinsic patterning cue to the future kelp embryo.
在许多复杂生物体中，母体组织在胚胎发生中的作用仍然是个谜。在这里，我们研究了母体组织对海带胚胎顶 - 基模式形成的贡献。以裙带菜为研究对象，我们使用显微手术、细胞壁修饰染色、形态测量、流式细胞术、基因分型以及一种同步海带胚胎发生的改良海带受精方案，研究了与母体组织分离的影响。分离的胚胎更圆，且常常表现出异常形态。当卵原细胞的一部分细胞壁仍附着在合子上时，顶 - 基模式形成得以挽救。此外，与母体组织缺乏接触会增加孤雌生殖，这突出了母体信号在发育初始阶段的关键作用。这些结果表明，与母体卵原细胞壁的连接在海带的顶 - 基模式形成中起关键作用。这一观察结果让人联想到另一种褐藻——墨角藻，在墨角藻中细胞壁决定细胞命运。我们的研究结果表明，在系统发育上相距遥远的卵式生殖谱系中存在一种保守机制，其中硫酸化F2岩藻聚糖的局部分泌介导了顶 - 基极性的建立。在这个模型中，母体卵原细胞壁通过为未来的海带胚胎提供外部模式线索来介导基细胞命运的决定。
