Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznań, Poland.
Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznań, Poland; Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479, Poznań, Poland.
Phytochemistry. 2021 Jan;181:112571. doi: 10.1016/j.phytochem.2020.112571. Epub 2020 Oct 30.
Glucosinolates are unique thioglucosides that evolved in the order Brassicales. These compounds function in plant adaptation to the environment, including combating plant pathogens, herbivore deterrence and abiotic stress tolerance. In line with their defensive functions glucosinolates usually accumulate constitutively in relatively high amounts in all tissues of Brassicaceae plants. Here we performed glucosinolate analysis in different organs of selected species representing Capsella, Camelina and Neslia genera, which similarly as the model plant Arabidopsis thaliana belong to the Camelineae tribe. We also identified orthologs of A. thaliana glucosinolate biosynthetic genes in the published genomes of some of the investigated species. Subsequent gene expression and phylogenetic analyses enabled us an insight into the evolutionary changes in the transcription of these genes and in the sequences of respective proteins that occurred within the Camelineae tribe. Our results indicated that glucosinolates are highly abundant in siliques and roots of the investigated species but hardly, if at all, produced in leaves. In addition to this unusual tissular distribution we revealed reduced structural diversity of methionine-derived aliphatic glucosinolates (AGs) with elevated accumulation of rare long chain AGs. This preference seems to correlate with evolutionary changes in genes encoding methylthioalkylmalate synthases that are responsible for the elongation of AG side chains. Finally, our results indicate that the biosynthetic pathway for tryptophan-derived indolic glucosinolates likely lost its main functions in immunity and resistance towards sucking insects and is on its evolutionary route to be shut off in the investigated species.
硫葡糖苷是 Brassicales 目中特有的硫葡糖苷。这些化合物在植物适应环境中发挥作用，包括抵御植物病原体、防止草食动物侵害和耐受非生物胁迫。根据其防御功能，硫葡糖苷通常在芸薹属植物的所有组织中以相对较高的量组成型积累。在这里，我们对代表荠属、芝麻菜属和雀儿豆属的选定物种的不同器官进行了硫葡糖苷分析，这些物种与模式植物拟南芥一样，属于芝麻菜族。我们还在一些研究物种的已发表基因组中鉴定了拟南芥硫葡糖苷生物合成基因的同源物。随后的基因表达和系统发育分析使我们能够深入了解这些基因在转录水平上以及在芝麻菜族内发生的相应蛋白质序列上的进化变化。我们的结果表明，硫葡糖苷在调查物种的蒴果和根中含量很高，但在叶片中几乎不产生，如果产生的话也很少。除了这种不寻常的组织分布外，我们还发现甲硫氨酸衍生的直链硫葡糖苷 (AGs) 的结构多样性降低，而罕见的长链 AGs 积累增加。这种偏好似乎与编码甲基硫代烷基丙二酸合酶的基因的进化变化相关，这些基因负责 AG 侧链的延长。最后，我们的结果表明，色氨酸衍生的吲哚硫葡糖苷的生物合成途径可能在免疫和抵抗刺吸式昆虫方面失去了其主要功能，并且在进化过程中可能在研究物种中被关闭。
