SummaryThe origin story of land plants – the pivotal evolutionary event that paved the way for terrestrial ecosystems of today to flourish – lies within their closest living relatives: the streptophyte algae. Streptophyte cell wall composition has evolved such that profiles of cell wall polysaccharides can be used as taxonomic markers. Since xyloglucan is restricted to the streptophyte lineage, we hypothesized that fungal enzymes evolved in response to xyloglucan availability in streptophyte algal or land plant cell walls. The record of the origins of these enzymes is embedded in fungal genomes, and comparing genomes of fungi that share an ancient common ancestor can provide insights into fungal interactions with early plants. This Viewpoint contributes a review of evidence underlying current assumptions about the distribution of xyloglucan in plant and algal cell walls. We evaluate evolutionary scenarios that may have given rise to the observed distribution of putative xyloglucanases in fungi and discuss possible biological contexts in which these enzymes could have evolved. Our findings suggest that fungal xyloglucanase evolution was more likely driven by land plant diversification and biomass accumulation than by the first origins of xyloglucan in streptophyte algal cell walls.

中文翻译：

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真菌中木葡聚糖降解酶的起源


摘要陆地植物的起源故事——为当今陆地生态系统的繁荣铺平道路的关键进化事件——在于它们最近的现存亲戚：链藻。链霉菌细胞壁组成已经进化，因此细胞壁多糖的谱可以用作分类标记。由于木葡聚糖仅限于链霉菌谱系，我们假设真菌酶是响应链藻或陆地植物细胞壁中木葡聚糖的可用性而进化的。这些酶起源的记录嵌入在真菌基因组中，比较具有古老共同祖先的真菌基因组可以深入了解真菌与早期植物的相互作用。本观点有助于回顾当前关于木葡聚糖在植物和藻类细胞壁中分布的假设所依据的证据。我们评估了可能导致在真菌中观察到的假定木葡聚糖酶分布的进化情景，并讨论了这些酶可能进化的可能生物学背景。我们的研究结果表明，真菌木葡聚糖酶的进化更可能是由陆地植物多样化和生物量积累驱动的，而不是由链藻藻细胞壁中木葡聚糖的最初起源驱动的。