mixoploid plants but tetraploid plants had lower amounts of this substance in
comparison with diploids. Our results suggest that tetraploidization was not useful
for production of tetrahydrocannabinol for commercial use but mixoploids were
found suitable.
17.1 Introduction
Cannabis sativaL. as one of the earliest domesticated plant species and has been
used for millennia as a source offibre, oil and protein-rich achenes and for its
medicinal and psychoactive properties. From its site of domestication in Central
Asia, the cultivation of Cannabis spread in ancient times throughout Asia and
Europe, and is now one of the most widely distributed cultivated plants (Schultes
et al. 1974 ). Hempfibre was used for textile production in China more than
6000 years ago (Li 1973 ). Archaeological evidence for the medicinal or shaman-
istic use of Cannabis was found in a 2700-year old tomb in north-western China and
a Judean tomb 1700 years ago (Zias et al. 1993 ; Russo et al. 1974 ).Cannabishas a
diploid genome (2n = 20) with a karyotype composed of nine autosomes and a pair
of sex chromosomes (X and Y). Female plants are homogametic (XX) and males
heterogametic (XY) with sex determination controlled by an X-to-autosome bal-
ance system (Ming et al. 2011 ). The unique pharmacological properties of Cannabis
are due to the presence of cannabinoids, a group of secondary metabolits. Over 60
cannabinoids are known, the most abundant ones being cannabidiol (CBD),
D9-tetrahydrocannabinol (THC), and cannabinol (CBN), which are the criteria for
distinguishing between the hemp chemotypes (especially D9-THC, CBD and
THC/CBD ratio) that mainly accumulate in femaleflowers (“buds”) (ElSohly and
Slade 2005 ; Mehmedic et al. 2010 ). (Our results on native strain of Iran showed
different state in cannabinoids localization). For example in some cases there were
not a significant difference between the amount of cannabinoids inflowers and
leaves atflowering stage (Mansouri et al. 2009 ). In one experiment that we used
natural light for plant growth, THC content in the male and female leaves was
higher than the male and femaleflowers (Mansouri and Rohani 2014 ). It appears
that the cannabinoids aggregation pattern can change in different conditions.
17.1.1 Different Methods to Increase Plant
Secondary Metabolites
Plants produce a vast and diverse assortment of organic compounds, the great
majority of which do not appear to participate directly in growth and development.
These substances, traditionally referred to as secondary metabolites, often are dif-
ferentially distributed among limited taxonomic groups within the plant kingdom
366 H. Mansouri and M. Bagheri