How Embryophytic is the Biosynthesis of Phenylpropanoids and their Derivatives in Streptophyte Algae?
How Embryophytic is the Biosynthesis of Phenylpropanoids and their Derivatives in Streptophyte Algae?
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DOI：
10.1093/pcp/pcx037
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发表时间：
2017-05-01
影响因子：
4.9
通讯作者：
Archibald, John M.
中科院分区：
文献类型：
--
作者：
de Vries, Jan;de Vries, Sophie;Archibald, John M.
陆地植物起源于藻类是进化生物学中一个长期存在的问题。越来越清楚的是，许多曾经被认为是“胚体特异性”的特征实际上可以在它们最接近的藻类亲戚--链藻中找到。一个这样的情况是苯丙烷途径。虽然生物化学数据表明，链霉菌藻类港口木质素样成分，苯丙素核心途径，这是木质素生物合成的骨干，已提出已经出现在陆地植物的基础。在这里，我们重新审视这一假设，使用丰富的新的序列数据从链藻。追踪木质素生物合成的生化途径，我们发现，苯丙素合成所需的基因和木质素生产的前体已经存在于链霉菌藻类。然而，系统发育分析和蛋白质结构预测的关键酶类之一，木质素生产，肉桂醇脱氢酶（CAD），表明链霉菌藻类的CAD更类似于芥子醇脱氢酶（SAD）。这表明链藻中导致木质素生物合成的途径的终产物可能促进木质素样化合物和防御分子的产生。我们假设链霉菌藻类已经拥有遗传工具包，随后在维管植物中进化出产生木质素的能力。
The origin of land plants from algae is a long-standing question in evolutionary biology. It is becoming increasingly clear that many characters that were once assumed to be 'embryophyte specific' can in fact be found in their closest algal relatives, the streptophyte algae. One such case is the phenylpropanoid pathway. While biochemical data indicate that streptophyte algae harbor lignin-like components, the phenylpropanoid core pathway, which serves as the backbone of lignin biosynthesis, has been proposed to have arisen at the base of the land plants. Here we revisit this hypothesis using a wealth of new sequence data from streptophyte algae. Tracing the biochemical pathway towards lignin biogenesis, we show that most of the genes required for phenylpropanoid synthesis and the precursors for lignin production were already present in streptophyte algae. Nevertheless, phylogenetic analyses and protein structure predictions of one of the key enzyme classes in lignin production, cinnamyl alcohol dehydrogenase (CAD), suggest that CADs of streptophyte algae are more similar to sinapyl alcohol dehydrogenases (SADs). This suggests that the end-products of the pathway leading to lignin biosynthesis in streptophyte algae may facilitate the production of lignin-like compounds and defense molecules. We hypothesize that streptophyte algae already possessed the genetic toolkit from which the capacity to produce lignin later evolved in vascular plants.