2019/08/29 by Matthew E. Bergman, Ángel Chávez, Albert Ferrer +1 · 34 citations
Biochemistry, Genetics and Molecular Biology · Agricultural and Biological Sciences · Chemistry · #Plant biochemistry and biosynthesis #Essential Oils and Antimicrobial Activity #Plant and animal studies #Monoterpene #Geraniol #Pulegone #Citronellol #Chemotype #Carvone #Botany #Terpene #Population #Chemistry #Pelargonium #Biology #Biosynthesis #Sesquiterpene #Limonene #Biochemistry #Essential oil #Enzyme
paper · pdf · doi:10.1093/jxb/erz397
published in Journal of Experimental Botany 71(1), 258-271 (Oxford University Press)
openalex publication_date 2019/08/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Pelargonium graveolens is a wild predecessor to rose-scented geranium hybrids prized for their essential oils used as fragrances and flavorings. However, little is known about their biosynthesis. Here we present metabolic evidence that at least two distinct monoterpene biosynthetic pathways contribute to their volatile profiles, namely, cyclic p-menthanes such as (-)-isomenthone and acyclic monoterpene alcohols such as geraniol and (-)-citronellol and their derivatives (referred to here as citronelloid monoterpenes). We established their common origin via the 2C-methyl-d-erythritol-4-phosphate pathway but found no indication these pathways share common intermediates beyond geranyl diphosphate. Untargeted volatile profiling of 22 seed-grown P. graveolens lines demonstrated distinct chemotypes that preferentially accumulate (-)-isomenthone, geraniol, or (-)-citronellol along with approximately 85 minor volatile products. Whole plant 13CO2 isotopic labeling performed under physiological conditions permitted us to measure the in vivo rates of monoterpenoid accumulation in these lines and quantify differences in metabolic modes between chemotypes. We further determined that p-menthane monoterpenoids in Pelargonium are likely synthesized from (+)-limonene via (+)-piperitone rather than (+)-pulegone. Exploitation of this natural population enabled a detailed dissection of the relative rates of competing p-menthane and citronelloid pathways in this species, providing real time rates of monoterpene accumulation in glandular trichomes.