This document discusses mutation breeding techniques for several flower crops. It begins by explaining naturally occurring and induced mutations. Various mutagens like radiation and chemicals are described. Examples of mutation breeding programs for petunia, chrysanthemum, tulip, carnation, rose and gladiolus are provided where mutants with new flower colors and morphologies were obtained. The conclusion states that mutation breeding is a beneficial tool for plant breeders to generate novel traits and expand genetic diversity in crops.

1. MUTATION BREEDING IN FLOWER CROPS
M.KUMARESAN
Ph. D. IN FLORICULTURE AND LANDSCAPING

2. MUTATION BREEDING
 “Any heritable change in the idiotypic constitution of
sporophytic or gametophytic plant tissue, not caused by
normal genetic recombination or segregation”
(Harten, 1998)
 Such changes are capable of bringing about new and heritable
character variations in crop plants and such variations can be
selected and used for the establishment of crop varieties with
new characters.
 Mutations occur in nature in very low frequency. Such mutations
are called Spontaneous mutations..

3. However, the frequency of mutations can be increased with the
help of certain chemical or physical agents that are called mutagens
or mutagenic agents and mutations induced in this way are called
induced mutations.
This approach of plant breeding in which new variations of crops
with desirable characters are developed with the help of induced
mutations is called mutation breeding

4. NATURALLY OCCURRING MUTATIONS
Mutations occur spontaneously in natural settings quite
frequently.
They can happen due to mistakes made during cell replication
or exposure to mutagens such as radiation.
It is estimated that a mutation occurs every 10-8 base pair per
generation in eukaryotic genomes (Drake et al., 1998).
 Mutations in somatic cells cannot be easily tracked, nor can
they be passed on to future generations, and so are only
important in vegetatively propagated species.

5. MUTAGENS AND THEIR MODE OF ACTION
 Physical Mutagens
 Chemical Mutagens

6. PHYSICAL MUTAGENS
 Physical agents that are capable of inducing mutations. These are
different types of radiations. Radiations can be generally classified
into two classes based on their energy levels.
Radiations with lower energy levels are capable of causing
excitations at the level of nitrogen bases of the genetic material and
they are called non-ionizing radiations.
UV light is a good example of non-ionizing radiations.
Radiations with high energy level are capable of causing both
excitation and ionization at the level of nitrogen bases. They are
called ionizing radiations. X-rays, gamma rays, alpha particles,
beta particles etc are the examples of ionizing radiations.

7. CHEMICAL MUTAGENS
Chemicals that are capable of enhancing the frequency
of mutations. The chemical mutagens are mainly
classified into three categories on the basis of their
nature of action.
Alkylating Agents
Base Analogues
Acridine Dyes

8. ALKYLATING AGENTS
They induce mutations by adding an alkyl group (ethyl or
methyl group) to the nitrogen bases. The major alkylating
agents are:
•Ethyl Methane Sulphonate (EMS)
•Methyl Methane Sulphonate (MMS)
•Ethylene Imines (EI) etc.
Since the actions of alkylating agents resemble the actions of
radiations they are known as radiomimetic chemicals.
AT-GC transition and GC-AT transition

9. BASE ANALOGS
• These are chemicals analogous to nitrogen bases.
• They can get incorporated into DNA at the time of replication
and can cause wrong base pairing resulting in mutations. 5-
bromo uracil and 2-amino purine are the common base
analogues used as mutagens.
• AT-GC transition

10. OTHER CHEMICAL MUTAGENS
• Other chemicals like nitrous acid, hydroxylamine and
sodium azide are also efficient mutagens.
• AT-GC and GC-AT transition

11. PROCEDURE OF MUTATION BREEDING
It includes:
1. Selection of the material
2. Choice of the mutagen
3. Mutagen Treatment
4. Handling of the mutated populations in the case of
seed propagated species
5. Handling of mutated populations in the case of
clonally propagated species

12. APPLICATIONS OF MUTATION BREEDING
Mutation breeding can be used to develop improved
crop varieties, to induce male sterility, for the
production of haploids, to create additional genetic
variability, and to improve the adaptability of crops.

13. Genetic variation is necessary in any plant breeding program
for crop improvement.
Induced mutations are highly effective to enhance natural
genetic resources and have successfully assisted in developing
improved and new cultivars among both seed and vegetatively
propagated crops.
So far, among more than 2300 officially released mutant
varieties worldwide, 566 represent ornamental plants.

14. Some of the selected traits of the mutant ornamental plants are
flower color , flower morphology, plant architecture, compact
growth, flower type, and variegated leaves.
Among mutagens, gamma rays have been commonly used
effectively for mutation induction.
Recently, heavy-ion beam (HIB) has attracted increasing interest
in floriculture for mutation induction.

15. Some of the selected traits of the mutant ornamental plants are
flower color , flower morphology, plant architecture, compact
growth, flower type, and variegated leaves.
Among mutagens, gamma rays have been commonly used
effectively for mutation induction.
Recently, heavy-ion beam (HIB) has attracted increasing interest
in floriculture for mutation induction.

16. Mutation-assisted breeding (MAB) together with biotechnology
can contribute greatly for genetic improvement of ornamental
plants and in up lifting the socio-economic benefits in the
developing countries.
 In this article, an overview of mutation breeding of selected
ornamental plants and successful examples of ornamental mutants
developed in Thailand, Malaysia and Indonesia.

17. MUTATION BREEDING
OF FLOWER CROPS

18. MUTATION BREEDING OF PETUNIA
Mutation induction program was started in 1963.
An old variety known as "purpurea" with tall single stems and purple
flowers was taken for experiments.
Seed samples of 1000 seeds each were treated with thermal neutrons at
Brookhaven National Laboratory twice, in 1963 and 1967, using thermal
neutron flux of 2.9–3.4 x 109 nth/cm2.sec. and irradiation time of 30–60–90–
120 minutes.
In the M1 generation some interesting chlorophyll as well as morphological
changes were observed, which were described else where (Muszynski, 1964,
1967, 1968, 1975).
Selection of mutants in the subsequent generations yielded many mutants,
some of which are very valuable for further breeding of the super bissima
petunias.

19. MUTATION BREEDING OF PETUNIA

20. MUTATION BREEDING OF CHRYSANTHEMUM
A.K.A. Mandal,
Rooted cuttings of Chrysanthemum morifolium cv. Maghi, a
small flowered, late blooming cultivar, were treated with different
doses of gamma rays.
Somatic mutations in flower colour (light mauve, white, light
yellow and dark yellow) and chlorophyll variegation in leaves
were detected as chimeras in treated populations.
Plant regeneration was successful from all of the mutated tissues.
Plants with chlorophyll variegation in leaves and two new flower
colours (light mauve and white) were isolated in pure form with
64% and 100% efficiency of mutant recovery respectively.

21. MUTATION BREEDING OF CHRYSANTHEMUM

22. MUTATION BREEDING OF TULIP:
New cultivars can be obtained by mutation breeding.
Spontaneous mutations are found regularly in tulips.
Mutations can show another flower (edge) colour or flower
shape (parrots, fringed and double).
Differences exist in the mutation sensitivity of cultivars.
Many mutants are known from cultivars, like ‘Bartigon’,
‘William Copland’, ‘Murillo’ and ‘Apeldoorn’.

23. In order to stimulate mutations artificially, the possibilities of
Röntgen (X-rays) for mutation breeding in tulips have been
investigated.
Main bulbs as well as daughter bulbs can be used for mutation
induction; the dosage required varies from 350 to 550 rad.
Tri- and tetraploids need a higher dose than diploids.
The radiation can be applied early in the planting season
(August) or late (November). Using early radiation, many
deformed plants are found in the field in spring and sometimes
mutations are already visible.
Late radiation gives no deformation in the first year, but does
do so in the second year of cultivation, when many bulbs will not
flower

24.  All plants have to be cultivated three to four years, before
selection for mutations can begin.
Again, differences between cultivars can be found in the
number of mutations obtained.
Besides mutations in flower colour and flower shape
mutations also occur in the colour of the leaf edge, in plant
length and in bulb production.
In 1975, 1977 and 1978 several radiation mutants of
‘Preludium’ and ‘Lustige Witwe’ were released by PRI.
One of the mutants was ‘Santina’, a leaf edge mutant of
‘Lustige Witwe’. Many breeders are still using the mutation
techniques developed by PRI.

25. MUTATION BREEDING OF CARNATION
Chemical mutagens, the efficiency and effectiveness are
necessary to study the effective dose that can brings the broad
spectrum of variability.
Three different concentrations (0.1, 0.4 and 0.7%) of colchicine
(Col), ethyl methane sulphonate (EMS) and sodium azide (SA)
were used to treated Dianthus seeds to assess seed germination
behaviour, pollen sterility and mutagenic effectiveness.
It was noted that increase in the dose of EMS and SA,
germination percentage and survivability were decreased; whereas
colchicine doses were proportional to increase germination
percentage at seedling stage, but they were not survived till
maturity.

26. MUTATION BREEDING OF CARNATION
Pollen sterility increased with increasing mutagenic doses. The maximum
pollen sterility (61.1%) was observed under 0.7% colchicine. So, the effect
of chemical mutagenesis on seedling and pollen sterility with EMS
(especially 0.7%) treatment is much more beneficial as compared to
colchicine and SA.
 0.4% colchicine is effective for other agronomical characters.
The highest mutagenic frequency (13.953) was observed at 0.4% Col and
lowest one (4.464) at 0.1% Col.
The mutagenic effectiveness was maximum (86.42%) at 0.1% EMS and
minimum (13.824%) in 0.7% Col. The highest mutagenic efficiency (6.977)
was recorded in 0.4% Col and lowest (0.995) in 0.7% SA on the basis of
survivability. The effectiveness of the three chemicals on Dianthus is ranked
as EMS>Col>SA.

27. MUTATION BREEDING OF ROSE
Gamma irradiation of buds/scions with 4–10 KR of gamma-
rays of cvs like 'Christian Dior', 'Kiss of Fire', 'Gulzar', etc…,
and the budding on the Rosa indica odorata major cytology of
12 distinct induced colour mutants obtained by both EMS and
gamma-rays .
The cytology of the varied morphological mutants seems to be
responsible for mutations of colour and habit.

28. MUTATION BREEDING OF ROSE

29. MUTATION BREEDING OF LOTUS
Mutation induction by γ and X-ray irradiation in tissue
cultured lotus:
Mutations of tissue cultured lotus were induced by treating
plantlets with either acute -rays at doses of 0, 2, 3, 4, 5 or 6 krad
or X-rays at doses of 0, 1, 2, 3, 4 or 5 krad.
The 2-krad dose of either - or X-ray treatments resulted in a
50% survival rate.
The use of - and X-rays to induce mutation in lotus resulted in
21 altered characteristics.

30. Mutants from 1- and 2-krad of either or X-rays had long
secondary roots and numerous adventitious roots.
These mutants also exhibited good shoot growth and
healthy rhizome development.
Most plants treated with 3–5 krad of either - or X-rays
exhibited abnormal characteristics including vitrification,
chlorosis, deformed petioles and in addition had inhibited
growth of lateral buds, secondary roots and rhizomes.

31. MUTATION BREEDING OF GLADIOLUS
Studies on induction of flower color mutants in gladiolus
(Gladiolus x grandiflora Hort.) by gamma irradiation and
tissue culture:
 Most of the commercial varieties of gladiolus have been raised
by cross breeding during the last 10 decades.
 The purpose of this study was to establish the method for
obtaining solid mutants of gladiolus having novel flower color by
using gamma irradiation and / or tissue culture.

32. CONCLUSION:
Mutation breeding has long been a beneficial tool in not only the
plant breeder’s tool box, but also basic geneticist’s.
In crops where diversity for a given trait is low or non-existent,
induced mutagenesis provides an avenue of possibility.
With a clear objective, efficient mutagenic protocol, and a high
throughput and efficient phenotypic screening method, mutagenesis
can be of great benefit for the improvement of crop plants.