TITLE:
Genetic Variability and Elite Line Selection for High Essential Oil and Nepetalactone Content in Catmint (Nepeta cataria L.)
AUTHORS:
Abhilasha Srivastava, Soni Gupta, Swati Singh, Ram Swaroop Verma, Ramesh Kumar Srivastava, Anil Kumar Gupta, Raj Kishori Lal
KEYWORDS:
Gas Chromatography-Mass Spectrometry, Genetic Improvement, Half-Sib Selection, Insect Repellent, Principal Component Analysis
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.12 No.7,
July
29,
2021
ABSTRACT: Nepeta cataria L., commonly known as catmint
or catnip, belongs to the family “Lamiaceae” and is indigenous to Europe and Asia. The essential oil of this species
is known for the richness and diversity of nepetalactones (NPL) which are used
as mosquito/insect repellents in perfumery and cosmetic industries. Reports on
Indian catmint germplasm are very meager and warrants exploration of its
commercial potential as a natural, non-toxic source of insect repellents. With
this objective, commercial open-pollinated seeds of catmint collected from its
native, temperate habitat in Himalayas were introduced in the tropical plains.
Subsequent to adaptation to a new zone we were able to isolate nineteen
individual plants based on plant growth. Hydrodistillation of the fresh herb
yielded essential oil in the range of 0.01% to 0.2%. Gas Chromatography (GC) and
GC-Mass Spectrometry (GC-MS) analyses of the oil revealed the dominance of
monoterpene hydrocarbon, namely, 4aα,7α,7aα NPL (1) isomer (84%). The
other two isomers of nepetalactone, 4aα,7α,7aβ NPL (2) and 4aα,7β,7aα
NPL (3) were also present, although in very less amounts (1.0% and 1.6%,
respectively). Sesquiterpenes identified were α-humulene (traces), (E)-caryophyllene (0.6%) and
caryophyllene oxide (1.7%). We compared the identified Indian catmint chemotype
with the other oils from temperate, sub-tropical and tropical locations based
on literature search. The Indian chemotype was found to be similar to the oils
from Burundi, France, Turkey, UK and USA, mainly due to more accumulation of 4aα,7α,7aα
NPL (1) isomer. These oils grouped together in Principal Component Analysis.
Breeding lines are presently being developed to improve yield related traits in
this plant. Multidisciplinary R&D efforts along with setting up industry
related guidelines are required to successfully commercialize catmint
cultivation. Several species of Nepeta genus have high nepetalactone content too and their potential as a commercial
source of these isomers still needs to be explored.