Key message

The investigation provides initial knowledge on the distribution and evolution of the high and low methyl salicylate-producing trait in the Betula genus. Mislabelled birch species could be identified and removed.

Abstract

The genus Betula is the largest group of ecologically and economically dominant perennial woody plants in subalpine forests. The taxonomy of Betula is complex due to an extensive history of hybridization and periodic introgression events among the species. Although almost all land plants including birches produce methyl salicylate (MeSA) as a signaling molecule and in response to stress (“low MeSA producer”), some birch species produce high amounts of MeSA in the leaves and bark (“high MeSA producer”). Unfortunately, the evolution of high levels of MeSA production in the genus Betula remains unclear. The salicylic acid-binding protein 2 (SABP2) and salicylic acid methyltransferase (SAMT) genes involved in MeSA biosynthesis were incorporated into this study to examine the interspecific relationship of high and low MeSA-producing birches. Additionally, eight chloroplast and three nuclear regions were included to evaluate their potential application in species determination. The analysis resulted in 25 and 61 nucleotide variations, respectively, which allowed for a visualization of the genetic architecture in the 18 Betula species investigated. The high MeSA-producing B. lenta, B. grossa, and B. alleghaniensis formed the basal clade in the phylogenetic analysis, thus revealing their ancestral status, and the network analysis postulates that the diploid B. lenta is one of the ancestors of the genus Betula. The results indicate that the ability to produce high levels of MeSA that were initially present in the genus has been lost several times during its evolution. Placing species of the subgenus Acuminata alongside the subgenus Betula, together with a fragrance analysis, questions their ability to produce high levels of MeSA.

中文翻译：

---

从多个叶绿体和核区域推断的桦属（Betula）属的种类确定和系统发育关系揭示了祖先的高水杨酸甲酯产生能力

关键信息

该研究提供了关于 桦 属中高和低水杨酸甲酯产生性状的分布和进化的初步知识。标识错误的桦树种可以被识别并去除。

抽象

桦树属是亚高山森林中具有生态和经济优势的多年生木本植物的最大种类。由于广泛的杂交历史和物种间的周期性渗入事件，桦属的分类学很复杂。尽管包括桦树在内的几乎所有陆地植物都产生水杨酸甲酯（MeSA）作为信号分子并响应压力（“ MeSA较低的生产者”），但某些桦树种在叶片和树皮中产生大量的MeSA（“ MeSA较高的生产者”） 。不幸的是，在桦属中高水平的MeSA生产的进化仍不清楚。水杨酸结合蛋白2（SABP2）和水杨酸甲基转移酶（SAMT）参与MeSA生物合成的基因被整合到这项研究中，以检验产生高和低MeSA桦树的种间关系。此外，还包括八个叶绿体和三个核区，以评估它们在物种确定中的潜在应用。该分析分别导致25和61个核苷酸变异，这使所研究的18种桦属物种的遗传结构可视化。高MeSA产生的B. lenta，B。grossa和B. alleghaniensis在系统发育分析中形成了基部进化枝，从而揭示了它们的祖先地位，并且网络分析假定该二倍体B. lenta是该祖先的祖先之一。桦属。结果表明，最初在该属中产生的高水平MeSA能力已经在其进化过程中丧失了数次。将Acuminata菌种与Betula菌种一起放置，并进行香气分析，质疑它们产生高水平MeSA的能力。