Peptidoglycan has been retained in chloroplasts that have evolved from cyanobacteria along some evolutionary tracks, but has seemingly been quickly eliminated during evolution of others. It has been eliminated in Rhodophyta, Chlorophyta, Pteridophyta and Spermatophyta, but has been retained in streptophyte algae, Glaukophyta, and Lycophyta. In this article questions emerging from this are raised, and for some of them answers are suggested.

中文翻译：

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真核生物中的肽聚糖：未解决的问题

肽聚糖一直保留在从蓝藻沿某些进化轨迹进化而来的叶绿体中，但似乎在其他进化过程中很快被消除了。它已在红藻门、绿藻门、蕨类植物和精子植物中被消除，但在链藻、绿藻门和石藻门中保留。本文提出了由此产生的问题，并为其中一些问题提供了答案。