Intrinsic factors part 2 Brief

Prepared by,
Dr. Preeti D. Verma
Asst. Professor, Department of Pharmacognosy
L. M. College of Pharmacy, Ahmedabad.
INTRINSIC/ENDOGENOUS FACTORS
AFFECTING CULTIVATION OF
MEDICINALPLANTS – Part 2
1

[2]
Mutation
2
Prepared by Dr. Preeti D. Verma for
Academic Purpose Only

Definition
• Changes in the genetic make-up of plants.
• Represented as variation in characters of the species.
• It is sudden Discontinuous or Permanent change in gene,
capable of producing great or small changes in some parts of
plant.
• It can be: Sex-linked or Autosomal
Germinal or Somatic
Dominant or Recessive
Lethal or Non-lethal
Useful or Deleterious.
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Causes of Mutation :
1. Environmental changes, or
2. Changes in hereditary constitution.
1. Environmental changes
• Variation occurs, but Original traits are restored when
changes in environment are also withdrawn or disappeared.
• This type of change and restorage is not heritable and also
not built into genotype.
• They are termed only as “Phenotypic variations” and
commonly called as “Modifications”.
5

2. Changes in hereditary constitution
• When a change occurs in the genome of an individual,
which is not caused due to environment, it may make a
permanent evolutionarychange.
• This is termed as “Mutation” and represents a sudden
change in genotype causing qualitative or quantitative
alterations of genetic material.
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2. Changes in hereditary constitution
Causes:
1. DNAfails to copy accurately
2. External influences can create mutations
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I. Types of Mutation:
1. Chromosomal Mutation
2. Point Mutation
1. ChromosomalMutation:
• Also called as “Chromosomal Aberration”.
• Leads to changes in amount or position of genetic
material i.e.
No. of Chromosomes
Sequence of Genes
Structure of Chromosomes
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2. Point Mutation:
The changes with a gene or cistron of DNA molecule (in
nucleotide sequence) cause point mutation.
Point Mutation
(A) Somatic:
Autosomal mutation
Recessive
Phenotypical
Effect not so profound
Not observed in progeny
(B) Germinal:
Sex-linked
Dominant
Genotypical
Effect profound
Progeny contain mutated genes

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CAT CAT CAT
GTA GTA GTA
CAT CAT TAT
GTA GTA ATA
CAT CAT GCAT
GTA GTA CGTA
CAT CA CAT
GTA GT GTA
Types of Point Mutation :
Substitution
Addition/ Insertion
Deletion
Original Sequence

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Types of
Point
Mutation :

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II. Types of Mutation:
1. Spontaneous mutation:
Mutation, which occurs due to some unknown reason from
nature.
Observed in some plants, bacteria, viruses, etc.
2. Induced mutation:
Mutations induced by artificial means with certain agents
called Mutagens.

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Mutagens:
A) Physical:
Exposure to UV rays, X-rays, ionizing radiations,
Abnormal environment, like elevated temperature, etc.

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Mutagens:
B) Chemical: Nitrogen mustard, Formaldehyde,
Deoxyadenosine, Nitrous acid, Ethyl ethane sulphonate,
Ethyl methane sulphonate, 5-bromouracil, 2-aminopurine,
sodium azide, Manganese chloride, inorganic cyanides,
etc.
The chemical mutagens have profound cellular effects, like
• Production of abnormal DNA(nitrogen mustard)
• Inhibition of deoxyribonucleotide synthesis
(deoxyadenosine)
• Inhibition of cytochrome oxidase with resultant peroxide
formation (inorganic cyanides).Prepared by Dr. Preeti D. Verma for

17
C) Enzymatic:
Alteration in DNA replicating, Recombination, DNA
repair systems, by certain enzymes.

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Significance of Mutation :
• The changes caused due to mutations include
morphological and anatomical changes, as well as,
changes in the chemical composition of the plants. This
is significant for the medicinal plants.
• In some cases, favourable (desirable) changes and yield
in active constituents of plants have been achieved.
• Mutations may help in building the resistance of a
medicinal plant towards certain disease.Prepared by Dr. Preeti D. Verma for

19
Examples of mutation in plants:
The artificial production of mutations in medicinal plants is an
important milestone in the development of cultivation
technology.
• The higher Solasodine content is achieved by applying
radiation and chemical mutagens in Solanum khasianum.
• Chemical mutagens have a successful use in increasing
Morphine content of Papaver somniferum.

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• The tuber yield and diosgenin content of Dioscorea bulbifera
is increased by radiation.

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• The economically important characters of Atropa belladonna
have been enhanced by radiations and chemical mutagens.

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• The agronomic performance and harvest index of Mentha
arvensis var. piperascens (Japanese mint) have been improved
by exposure to gamma radiations. The effects of artificial
mutations have been extensively studied on different species of
mentha.

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• The capsicum seeds (Capsicum annuum) treated with sodium
azide and ethyl methane sulphonate have led to plants giving
higher contents of capsaicin.

[3]
Polyploidy
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Polyploidy
Definition: Polyploidy is a condition in which the cells of
an organism have more than two sets of chromosomes
(homologous) in a nucleus.
• The specific number of chromosomes is a character of
each species and is called genome, which is observed, in
all types of organisms.
• But when the organism contains more than two
genomes, it is called polyploidy i.e.
• The no. of chromosome sets exceed than that of diploid
in the cells of organisms.

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No. of sets of
Chromosomes in
genome
Euploidy:
Variations that involve entire set of
chromosome (number of
chromosome sets in the nucleus)
Aneuploidy:
Variations that involve only
single chromosome of a set.

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I. Types of Polyploidy:
(Depending upon the no. of chromosome sets)
The polyploidy occurs in a multiple series of 3, 4, 5, 6, 7, 8,
etc. of the basic chromosome or genome number.
Accordingly, it is called triploidy (3n), tetraploidy (4n),
pentaploidy, hexaploidy, heptaploidy and octaploidy,
respectively.

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Originor Mechanism
• Failure of normal cell division results in nuclei with increased
sets of chromosomes.
• Disturbance to mitotic spindle of dividing diploid cell can
cause non-segregation of already duplicated chromosome
and thus convert diploid into tetraploid cells.
• A fusion of two diploid gametes (2n) produce tetraploid
individuals.
• A fusion of diploid (2n) & haploid (n) gametes produce
triploid individuals.

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4 copies of
same genome
2 copies of
same genome

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II. Types of Polyploids:
1. Autopolyploids
2. Allopolyploids
1. Autopolyploids
• Autopolyploids are polyploids with multiple
chromosome sets derived from a single taxon.
• Genomes coming together in the polyploid are
identical .
• If 1 set of chromosomes of a species is represented by
letter A,
Diploid will have AA &
Tetraploid will have AAAA (Autotetraploid).Prepared by Dr. Preeti D. Verma for

35
2. Allopolyploids
Polyploids with chromosomes derived from two or more
diverged taxa. i.e.
Polyploid species derived from parents that have structural
dissimilarity between their basic genomes. (via
hybridization).
Diploid set of chromosomes of one species: AA
Diploid set of chromosomes of other species: BB
The duplication will give Allotetraploid: AABB.

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Polyploidy: Types
1. Natural
2. Induced
a. Physical: like X-rays, centrifugation, temperature
shocks, mechanical injury.
b. Chemical agents: mainly Colchicine, Oryzalin,
veratrine, sulphanilamide, hexachlorocyclohexane
and mercuric chloride.
Colchicine is most widely used agent to induce
polyploidy (0.05% aq. Solution used).Prepared by Dr. Preeti D. Verma for

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Significance of Polyploidy:
Polyploidy is of greater significance to medicinal plants.
• It may cause formation of new species, adaptability to various
habitats and mainly accumulation of vitamins and metabolites.
• Induced polyploids are used by plant breeders for improving
yield.
• Polyploids are robust, more resistant, have large no. of leaves,
flowers & fruits, as compared to diploids.
• Polyploidy has exhibited various useful effects on medicinal
plants like Digitalis, Mentha species, Poppy, Plants
containing tropane alkaloids, Lobelia, etc.Prepared by Dr. Preeti D. Verma for

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Examples :
In Datura stramonium, yield of crop is enhanced by 60% in
4n form.
The plants like Lobelia, Opium, Cinchona, Belladonna,
Acorus, Squill, Cannabis: also show increased yield of
respective constituents in 4n form.
Polyploidy: cause a reduction of total glycosides of
Digitalis purpurea and D. lanata, but raises slightly the
contents of lanatosides A and B increase.

[4]
Hybridization
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Definition:
The process through which hybrids are produced is called
hybridization.
A hybrid is an organism, which results from crossing of
two species or varieties differing at least in one set of
characters.
The resultant hybrids are monohybrids (one pair of
different characters), dihybrids (two pairs of different
characters) or polyhybrid (more than 2 pairs of different
characters). Prepared by Dr. Preeti D. Verma for

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Significance: Hybrid plants
Hybridization helps in inducing in a single variety, the favourable
characters of other varieties of species and some times, producing
new and favourable characters which are not present in both the
parents.
Hybrid vigour (Heterosis): Superiority of hybrid over either
parents.
Plant hybrids are often created in order to select characteristics
from both parents in order to create an improved plant, by
improving production of seeds or fruit, or to make a plant hardier
or more disease resistant.Prepared by Dr. Preeti D. Verma for

44
Examples:
• The hybridization of Withania somnifera Israeli chemotype II and
W. somnifera South African chemotype have led to formation of a
new hybrid which contains 3 new withanolides.
• The hybrids like Digitalis purpurea X D. lanata and D. purpurea X
D. lutea contain principle glycoside as lanatoside A, along with
lanatosides B and E, but devoid of lanatoside C or Purpurea
glycoside A.
• Duboisia myoporoids & Duboisia leichardtii – F1 (More Hyoscine
& Hyoscyamine).

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• Datura stramonium & Datura ferox – F1 (More Hyoscine).
• Papaver somniferum & P. setigenum – F1 (More Codeine &
Thebaine).
• During the cross of Solanum incanum (1.8 % solasodine) and
S. melongena (traces of solasodine), first-generation bears more
fruits (berries) with solasodine up to 0.5%. Second generation
has proved to be a high yielding source for solasodine

[5]
Chemodemes
(Chemical Races)
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Definition:
Chemodemes are regarded as a group of plants of a species,
which have identical morphological characters, but differ in their
chemical nature.
Due to this, Chemodemes are considered as chemically separate
groups within species.
Or
Chemodemes are chemically distinct population within a species,
similar in phenotype, but different in genotype.
The variation between chemical races is strictly genetically-
mediated. Prepared by Dr. Preeti D. Verma for

48
The observation of chemodemes can be confirmed only
by growing different plants of a species in identical
conditions, preferably from the seeds and for many
generations.

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Examples:
1. Glycosides:
• In Digitalis purpurea, the races or strains identified are
storspeside, digitoxin and digipurpurin. These chemical races
yield different proportions of glycosides obtained from
digitoxin and gitoxin.
• Depending on content of lanatosides A and C the chemical
races in D. lanata are D. lanata Ehrh, chemo varieties A and
C.
• The chemodemes in Rheum palmatum are also known, which
give differing values for rhein:chrysophanol ratio.Prepared by Dr. Preeti D. Verma for

50
The different varieties of Prunus communis (almond) differ by
presence or absence of amygdalin.
2. Alkaloids:
• Chemical races have also been in Claviceps purpurea,
Duboisiamyoporoides and Duboisia leichharditii.
• 3 chemotypes :Withania somnifera.Chemotype I contains
mainly withaferin A; chemotype II has similar compounds
with withanolide D and chemotype III contains withanolides
(A-E) (a mixture of steroidal lactones).

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3. Essential oils:
The plants like Cinnamomum zeylanicum, Ocimum
menthaefolium, Cinnamomum camphora, Eucalyptus dives,
and Ocimum sanctum, all of which contain volatile oil, have
chemical races, with varied content of aromatic constituents.

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Significance:
The discovery of chemodemes has enabled the
pharmacognosists to select high yielding chemical
strains or to eliminate chemical strains which contain
toxic principles.
The chemodemes are induced by breeding in some
species, so as to manipulate active constituents, with a
view to enhance the therapeutics efficacy.

Intrinsic factors part 2 Brief

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