Characteristics of an isomenthone‐rich somaclonal mutant isolated in a geraniol‐rich rose‐scented geranium accession of Pelargonium graveolens

Abstract

A somaclonal essential oil mutant (IRPG) was identified among the regenerants induced in callus cultures initiated with the leaf explants of geranium Pelargonium graveolens cv. Kunti. While the shoot essential oil of the wild-type parent was rich in geraniol, the oil of the IRPG had isomenthone as the major monoterpenoid component. The IRPG oil had about 71% isomenthone, 6% citronellol and 3% geraniol, as compared to the parental variety oil, in which isomenthone, citronellol and geraniol contents were about 8%, 13% and 40%, respectively.

Distinct metabolic pathways drive monoterpenoid biosynthesis in a natural population of Pelargonium graveolens

“…The overall magnitude of flux also grossly favored (−)-isomenthone production when the calculated rates of labeling were compared between the main end-products in each of the three chemotypes (1719 pmol 13 C mg −1 FW h −1 (−)-isomenthone in the (−)-isomenthone chemotype versus 218 and 70 pmol 13 C mg −1 FW h −1 (−)-citronellol and geraniol, respectively, in their respective chemotypes). Such a dominant role of the p -menthane pathway in determining product profiles would also be consistent with instances of spontaneous reversion of geraniol-rich cultivars to isomenthone-rich lines (Kulkarni et al , 1998; Gupta et al , 2001; Saxena et al , 2004). The identification of protein targets to overcome this natural tendency towards (−)-isomenthone production would be of value to breeders aiming to maximize geraniol and (−)-citronellol production, as well as their highly valued esters.…”

“…However, a high C:G ratio also correlates with low night-time temperatures in the ‘Graveolens G1’ clone (Doimo et al , 1999). Interestingly, citronelloid dominant cultivars readily revert to a wild-type, isomenthone-rich phenotype as a result of somatic mutagenesis (Kulkarni et al , 1998; Gupta et al , 2001; Saxena et al , 2004). Thus, the C:G ratio in citronelloid-rich cultivated varieties is under environmental control while the prevailing structural group (i.e.…”

Comparative investigations of the essential oils of two scented geranium (Pelargonium spp.) cultivars grown on Reunion Island

“…In this way, a comparative study of the composition of commercial rose-scented geranium oils from different countries revealed that there are various chemotypes, among which the Reunion Island or 'Bourbon' type, the Egyptian or North African type and the Chinese type are distinguished. 11,16,[28][29][30] The Chinese geranium oil is characterized by its high citronellol content and low geraniol content (ratio 3-4:1), whereas both the 'Bourbon' and the Egyptian types contain the main constituents citronellol and the geraniol in 1:1 ratio. 'Bourbon' and the Egyptian geranium oils are distinguished by their relative contents of guaia-6,9-diene and 10-epi-γ-eudesmol.…”

The Phytochemical Composition, Biological Effects and Biotechnological Approaches to the Production of High-Value Essential Oil from Geranium

“…In geranium, many authors reported the occurrence of somaclonal variations, which are different in morphology as well as in phytochemical compositions (Dunbar and Stephens 1989;Gupta et al 2001;Gupta et al 2002;Kulkarni et al 2012;Ravindra et al 2004;Ravindra and Kulkarni 2015). During the screening of calliclones of geranium, Saxena et al (2008a) observed two morphotypes that differed in the dentation patterns of leaves: one morphotype was with high dentated leaves (HDLs), and another was with low dentated round leaves (LDLs).…”