Aging and/or tissue‐specific regulation of patchoulol and pogostone in two Pogostemon cablin (Blanco) Benth. cultivars

Abstract

In Pogostemon cablin (Blanco) Benth. essential oil, patchoulol and pogostone are the two major bioactive phytochemicals while their in vivo biosynthesis remains largely unknown. In this study, seven genes of the plastidic methylerythritol 4-phosphate pathway (MEP) and three genes of the cytoplasmic mevalonate pathway (MVA) in two cultivars, HN and YN, were isolated. Gene expression and phytochemical profiles across leaves and stems at different developmental stages of the two cultivars were evaluated using quantitative reverse-transcription polymerase chain reaction and gas chromatography-mass spectrometry, respectively. Hierarchical analysis showed that the expression of MVA- and MEP-related genes was clustered similarly in the two cultivars. Phytochemical assay revealed that the contents of patchoulol in leaves and pogostone in stems were regulated in an aging-dependent manner. Pogostone was only detected in stems but not in leaves of the two cultivars. The Pearson correlation analysis suggested that several genes were presumably involved in the biosynthesis of patchoulol and pogostone. In the YN cultivar, the 1-deoxy-d-xylulose-5-phosphate reductoisomerase and isopentenyl pyrophosphate isomerase 2 genes, and 2-C-methyl-d-erythritol 4-phosphate cytidylyltransferase were positively responsible for patchoulol and pogostone biosynthesis, respectively. In the HN cultivar, 3-hydroxy-3-methylglutaryl-coenzyme A reductase and mevalonate diphosphate decarboxylase, and mevalonate kinase expression were positively associated with pogostone and patchoulol biosynthesis, respectively. The genes identified in this study are good candidates for the enhancement of patchoulol content in the leaves or pogostone content in the stems of P. cablin. Taken together, our results lay a solid foundation for better understanding of the mechanism underlying patchoulol and pogostone biosynthesis, which in turn may help to improve their content in P. cablin.

The essential oil of patchouli, Pogostemon cablin: A review

“…Pogostone was first identified by Klein et al The ratio of patchoulol to pogostone varies markedly in PEO, which may be due to the existence of different chemotypes of P. cablin , and/or selective accumulation of pogostone in stems . Very recently, two independent research groups have investigated these hypotheses in more detail and moreover suggested that tissue age may also play a role . All these factors together could certainly account for the high variability of the pogostone content in PEO, depending of the proportions of stems versus leaves and age of the cultivar used for the production of PEO.…”

“…Surveying the literature, there are quantitative papers on patchoulol and pogostone only. Both internal and external standardisation have been applied.…”

“…nonyl acetate 54 was used, which is an unfortunate choice as this is the only simple ester naturally occurring in PEO, albeit in low concentrations. The last two methods both used octadecane as i.s . Its b.p.…”

“…The detector temperature was 280 °C . In the last method the injector temperature was 230 °C and 1 μL (5% PEO in hexane) was injected with a split of 1:50 . Overall the fully published methods do not appear superior to the method using 1‐pentadecanol published 30 years ago .…”

Transcriptome analysis of two Pogostemon cablin chemotypes reveals genes related to patchouli alcohol biosynthesis

“…Recently, a number of studies have focused on individual key enzyme genes and transcription factors to elucidate the biosynthetic mechanism of PA ( Yan et al, 2021 ; Zhang et al, 2019b , 2019c ; Yu et al, 2015 ; Wang et al, 2019 ; Chen et al, 2020 ; Li et al, 2021 ). There are also some reports on the regulation of the synthesis of PA by exogenous plant hormones, circadian rhythms and developmental stages ( Wang et al, 2019 ; Chen et al, 2019 ; Ouyang et al, 2016 ; Liu et al, 2018 ). However, understanding the biosynthetic pathway and molecular regulation mechanism of PA is the key to effectively increasing its production.…”