Schmiderer Corinna, Steinborn Ralf, Novak Johannes
Institute of Animal Nutrition and Functional Plant Compounds, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
Genomics Core Facility, VetCore, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
Plant Physiol Biochem. 2023 Mar;196:318-327. doi: 10.1016/j.plaphy.2023.01.034. Epub 2023 Jan 19.
The diversity of plant monoterpenes is largely based on the catalytic activity of monoterpene synthases. Additionally, copy number variation of monoterpene synthase genes may contribute to the quantity of transcripts and hence to the essential oil profile. This study used whole-genome sequencing and digital PCR for the measurement of copy number variation and quantification of gene expression in three closely related Salvia species, namely Salvia officinalis, Salvia pomifera and Salvia fruticosa. Twelve, 13 and 15 monoterpene synthase-encoding open-reading frames were predicted for Salvia officinalis, Salvia pomifera and Salvia fruticosa, respectively. In Salvia officinalis, one of the open reading frames was disrupted indicating a pseudogene. Monoterpene synthase genes were generally single copy per haploid genome, only a few were double or triple copy genes. Expression levels of monoterpene synthases in leaves corresponded generally well with essential oil composition. In some cases, a higher expression level of a certain monoterpene synthase could be explained by its duplication or triplication. The very high content of thujones in Salvia pomifera, for example, was accompanied by gene duplication and increased gene expression of (+)-sabinene synthase responsible for the thujone precursor sabinene. In Salvia officinalis, three individuals different in their essential oil profile showed significant differences in their monoterpene synthase expression levels corresponding roughly to the profile of the essential oils. Transcript expression of monoterpene synthase genes were measured in leaf, calyx and corolla. The corolla differed significantly from leaves, while calyces usually showed a profile intermediary between leaf and corolla.
植物单萜的多样性很大程度上基于单萜合酶的催化活性。此外，单萜合酶基因的拷贝数变异可能会影响转录本的数量，进而影响精油的成分。本研究利用全基因组测序和数字PCR技术，对三种近缘鼠尾草属植物，即药用鼠尾草、石榴鼠尾草和灌木鼠尾草的拷贝数变异进行了测定，并对基因表达进行了定量分析。分别预测出药用鼠尾草、石榴鼠尾草和灌木鼠尾草有12个、13个和15个编码单萜合酶的开放阅读框。在药用鼠尾草中，有一个开放阅读框被破坏，表明是一个假基因。单萜合酶基因通常在每个单倍体基因组中为单拷贝，只有少数是双拷贝或三拷贝基因。叶片中单萜合酶的表达水平通常与精油成分吻合良好。在某些情况下，特定单萜合酶较高的表达水平可以通过其基因重复或三倍化来解释。例如，石榴鼠尾草中侧柏酮的含量非常高，同时伴随着负责侧柏酮前体桧烯的(+)-桧烯合酶的基因重复和基因表达增加。在药用鼠尾草中，三种精油成分不同的个体在单萜合酶表达水平上表现出显著差异，大致与精油成分相符。在叶片、花萼和花冠中测定了单萜合酶基因的转录表达。花冠与叶片有显著差异，而花萼的表达模式通常介于叶片和花冠之间。
