Breeding for different flower forms in ornamental crops

UNIVERSITY OF HORTICULTURAL SCIENCES, BAGALKOT
2nd SEMINAR
Breeding for different flower forms in ornamental crops
Takhellambam Henny Chanu
UHS18PGD253
Department of FLA
4/22/2021 Department of FLA 3

OUTLINE OF PRESENTATION
➢ Introduction
➢ ABCDE Flower Development Model
➢ Conventional breeding
➢ Genetic modification
➢ Case studies
➢ Future thrust
➢ Conclusion

INTRODUCTION
▪ Flower shape - important
characteristics of ornamental
plants.
▪ Creation of new flower shapes -
major breeding target of any
breeder.
▪ Modification in flower shape -
semidouble or double or in its
parts like petal or sepal or
serration is of high commercial
value
▪ Phenotype with unique flower
forms or, the double flower has
higher ornamental value than the
single
4/22/2021 Department of FLA
Figure 1: Forms of flower
5

Figure 2: Genetic analysis of flower development
4/22/2021 Department of FLA Suyama et al., 2010 6

ABC Flower Development Model
➢ George Haughn and Chris Somerville in 1988
➢ To explain how floral whorls develop
➢ Arabidopsis thaliana and Antirrhinum majus
Figure 3: ABC flower development model
Bowman et al. 1989 7

ABCDE Flower Development Model
➢ Arabidopsis thaliana and Snapdragon mutants
➢ Class A genes (APETALA1, APETALA2) controls sepal
development & together with class B genes, regulates the
formation of petals. Antirrhinum: LIPLESS 1 and 2
➢ Class B genes (e.g. PISTILLATA, and APETALA3), together
with class C genes, mediates stamen development. Antirrhinum:
DEFICIENS (DEF) and GLOBOSA (GLO)
➢ Class C genes (e.g., AGAMOUS), determines the formation of
carpel. Antirrhinum: PLENA (PLE)
➢ class D genes (e.g., SEEDSTICK, and SHATTERPROOF)
specify the identity of the ovule. Petunia: FBP7 and FBP11
➢ Class E genes (e.g., SEPALLATA), expressed in the entire floral
meristem and are necessary. (SEP1, SEP2, SEP3 and SEP4)
4/22/2021 Department of FLA Bowman et al. 1989 8

Figure 4: ABCDE flower development model
➢ Genes of ABCDE model are MADS-box genes.
Bowman et al. 1989 9

MADS-box
➢ Conserved sequence motif found in genes which comprise the MADS-box
gene family
➢ The MADS box encodes the DNA-binding MADS domain.
➢ MADS-domain proteins are generally transcription factors
➢ Length of the MADS-box - 168 to 180 base pairs
➢ Origin:
➢ MCM1 from the budding yeast, Saccharomyces cerevisiae
➢ AGAMOUS from the thale cress Arabidopsis thaliana
➢ DEFICIENS from the snapdragon Antirrhinum majus
➢ SRF (serum response factor) from the human Homo sapiens
➢ MADS-box genes - male and female gametophyte development, embryo and
seed development, root, flower and fruit development
➢ Floral homeotic MADS-box genes (AGAMOUS and DEFICIENS) – determine
floral organ identity according to the ABC model of flower development
4/22/2021 Department of FLA Bowman et al. 1989 10

HYBRIDIZATION
➢ Technique to induce variation in
floricultural crops
➢ Process of crossbreeding
between genetically dissimilar
parents to produce a hybrid.
➢ Crossing involves placing pollen
grains from one genotype, the
male parent, on to the stigma of
flowers of the other genotype,
the female parent
Figure 5: Hybridization technique
11

➢ Unique shape is by crossing two different forms
➢ Single, double, semi-double depending upon genetic
constitutions
➢ Single, semi-double and double types of flower in ornamental
crops are genetically controlled either by a single gene or
multiple genes.
➢ Select suitable genotype as a parent to develop new cultivars
having required flower type
Gaurav et al. 2017
12

Table 1: Inheritance of double flower character in flower
crops
4/22/2021 Department of FLA Gaurav et al., 2017 13

Nataraj et al., 2020
14

MUTATION BREEDING
➢ Freisleben and Lein (1944)
➢ Mutation breeding
➢ An attractive method for creating genetic variability -
ornamental plant
➢ Ornamental plants - Ideal systems for mutagenesis
➢ Heterozygous and vegetatively propagated – detection,
selection and conservation – M1
➢ Mutation induction led to changes in floral morphology -
ornamental value
Schum and Preil, 1998

MUTAGENS
Physical mutagens
1. Ionizing radiation
(a)Particulate radiations:
alpha-rays, beta-rays, fast
neutrons and thermal
neutrons
(b) Non-particulate radiations:
X-rays and Gamma rays
2. Non-ionizing radiation:
ultraviolet radiation
Chemical mutagens
1. Alkylating agents: EMS,
MMS, sulphur mustard,
nitrogen mustard
2. Acridine dyes: Proflavin,
acridine orange, acridine
yellow and ethidium
bromide
3. Base Analogues: 5 Bromo
uracil, 5 chloro-uracil
4. De-amination agents: Nitrous
acid, Sodium azide
4/22/2021 Department of FLA Schum and Preil, 1998 16

➢ Mutagenic treatment
➢ Acute – once in the shortest time
➢ Chronic – long period (weeks or months)
➢ Recurrent – two or more subsequent generations (M2, M3
or M4 after M1)
➢ Causes of mutation
➢ Genetic structure change
➢ Genome mutation
➢ Gene (point mutation) – alteration in nuclear DNA
➢ Specific sequence of nucleotide – new type of protein

Figure 6: Types of point mutation

Figure 7: Types of chromosomal mutation

Euphytica, 2014, 199:317–324
Isolation of flower color and shape mutations by
gamma radiation of Chrysanthemum morifolium
Ramat cv. Youka
Tarek M. A., Soliman, Suhui Lv, Huifang Yang, Bo Hong, Nan Ma, Liangjun Zhao
College of Agronomy and Biotechnology, China

Materials and methods
➢ Location: College of Agronomy and Biotechnology, China Agricultural
University, Beijing, China
➢ Plant materials : C. morifolium Ramat cv. Youka (spoon shape)
➢ Explants - petals flower buds
➢ Sterilzation procedure - 75 % alcohol for 20–30 s and 0.1 % HgCl2 solution
➢ Buds were opened and the white petals 4 mm were excised and cultured on
MS basal medium (Murashige and Skoog)
➢ pH - 6.0
➢ Culture room - 16/8 h light/dark regimes at 26 ± 1 C, 2,000 lux provided by
cool white fluorescent tubes and 55–60 % relative humidity
➢ Callus - gamma radiation using 60Co of gamma chamber with doses of 0
(Control), 10, 15 and 20 Gy and dose rate 1.02 Gy/min.
➢ Three replications were applied to each dose and each replication consist of
100 explants.
Tarek et al., 2014 21

Figure 8: In vitro regeneration C. morifolium ‘Youka’ from ray florets. a) White flower
buds; b) Callus induction medium; c) Adventitious shoots formation after 4 weeks;
d) In vitro Roots formations after 25 days; e) Plantlets in hardening chamber
4/22/2021 Department of FLA Tarek et al., 2014 22

Table 2: In vitro callus survival (%) and number of shoots (Mean ± SE) of white
C. morifolium ‘‘Youka’’ as influenced by gamma ray doses
Gamma ray dose (Gy) Callus survival (%) No. of shoot
0 86.67 7.22 ± 0.11
10 62.43 7.67 ± 0.33
15 30.33 7.89 ± 0.29
20 17.23 3.00 ± 0.29

Table 3: Effect of in vitro treatment of C. morifolium ‘Youka’ with gamma
radiation on flowering characteristics of the generated plantlets
Character mean ±
SE
Treatments
Control 10 Gy 15 Gy 20 Gy
Flower no. per plant 4.22 ± 0.29 4.38 ± 0.12 4.05 ± 0.14 3.00 ± 0.00
Flower diameter
(cm)
6.12 ± 0.23 6.11 ± 0.15 5.15 ± 0.18 4.88 ± 0.06
Petal length (cm) 3.03 ± 0.20 3.14 ± 0.19 3.00 ± 0.01 3.01 ± 0.01
Petal width (cm) 0.83 ± 0.07 0.87 ± 0.12 0.09 ± 0.03 1.05 ± 0.06
Petiole length (cm) 4.50 ± 0.17 4.72 ± 0.18 6.52 ± 0.29 6.51 ± 0.30
Petiole diameter
(cm)
2.50 ± 0.11 1.89 ± 0.04 1.89 ± 0.04 1.85 ± 0.04

Figure 9: Flower of tissue-raised plants of Chrysanthemum morifolium c.v Youka :
a. control, white colored with spoon shaped petals; b. M.1, white colored
with tubular petals; c. M.2, yellow colored with spoon shaped petals;
d. M.3, yellow colored with flat shaped petals
4/22/2021 Department of FLA Tarek et al., 2014 25

Figure 10: Flower shape mutants of carnation variety ‘Vital’ by ion
beam irradiation
4/22/2021 Department of FLA Okamura et al., 2003 26

Figure 11: Gamma irradiated Torenia hybrida flowers with erose petal
margins (control on the right, mutants treated with 0.0075
mM colchicine for 48 h and 30 Gy gamma radiation center
and left). Scale bar in cm.
4/22/2021 Department of FLA Suwansere et al., 2011 27

Figure 12: Mutants of Arka Violet Cushion
Kumar, 2018

Promising mutants from Thai Chen Queen isolated
30

Table 4: Induced mutation for change in flower morphology in
flower crops

Limitation
➢ Random and unpredictable
➢ Frequency of desirable mutation is very low - 0.1% of the
total mutations.
➢ Useful mutants are rare and predominantly recessive
➢ Desirable mutation associate with undesirable side effects
➢ Mutants - strong negative pleiotropic effects on other traits
➢ Field trial and germplasm storage - expensive and require a
lot of space and careful management
➢ Screen large population to select desirable mutations
➢ Health risks: handling, chemical mutagens; radiations, fast
neutrons treatments

POLYPLOIDY
➢ Polyploidy – cells of an organism have more than two
paired sets of chromosome
➢ Doubling the chromosome number of a species
➢ Create variations in the species where the natural
variations are limited
➢ Genetic variations – breeding program
➢ Useful in several crops for breeding purpose
➢ Increased in size and shape of plants, their leaves,
branches, flower parts, fruits, and seeds
➢ Improved plant architecture - provide good material for the
breeding programme and for further development of
cultivars
Mata, 2009

Figure 13: Factors affecting plant in vitro artificial polyploidy induction system
4/22/2021 Department of FLA Niazian and Nalousi, 2020 34

COLCHICINE
➢ Alkoloid - Colchicum autumnale
➢ C22H25O6N
➢ Interferes with the development of spindle apparatus
➢ Sister chromatids of chromosomes are unable to migrate to the opposite poles –
anaphase
➢ Chromatids (=4) are included in the same restitution nucleus leading to
chromosome doubling
➢ Blakesle, Avery and Nebel in 1937.
4/22/2021 Department of FLA Mata, 2009 35

Figure 14: The phenomenon of giga after polyploidization in plants
4/22/2021 Niazian and Nalousi, 2020
Department of FLA 36

Folia Hort., 2018, 30(2): 307-319
Induction and identification of colchicine induced
polyploidy in Gladiolus grandiflorus ‘White
Prosperity’
Ayesha Manzoor, Touqeer Ahmad, Muhammad Ajmal
Department of Horticulture, PMAS Arid Agriculture University Rawalpindi,
Pakistan

MATERIAL AND METHODS
➢ Experimental site - Pakistan from September 2015 to April
2016.
➢ Plant material - Corms ‘White Prosperity - 2.6 cm
➢ The non-dormant corms were soaked in 0.1%, 0.2% and
0.3% colchicine solution, while control corms were soaked
in distilled water for 24 h
➢ Completely randomized design (CRD) having 4 treatments
and 3 replications consisting of 16 corms in each
replication.
Manzoor et al., 2018

Table 5: Reproductive parameters of control and colchicine treated plants
of gladiolus ‘White Prosperity’

Figure 15: Impact of different concentrations of colchicine on floret
diameter in gladiolus ‘White Prosperity’: floret diameter was
less in control (a) and at 0.1% (b) but it was increased at 0.2%
(c) and was maximum at 0.3%

Figure 16: Morphological variation in flower petals of gladiolus ‘White
Prosperity’: petals had smooth edges and triangular shape in control plants (a)
pointed outgrowth appeared on petal surface in treated plants along with
elongated petal shape and serrated margins at 0.1% colchicine (b), flower
produced oval shaped petals whose one end had ruffled edges at 0.2% colchicine
(c) petals with pointed outgrowth were also produced at 0.3% colchicine (d)

Figure 17: Flowers of the diploid (right) and tetraploid (left) regenerated
from sectioning of PLBs of P. schilleriana
Chen et al., 2008
42

GENETIC MODIFICATION
➢ Development of new ornamental varieties through gene
transfer
➢ Development of new varieties - hybridization or
mutagenesis is very difficult
➢ Introduce traits which can’t be generated by conventional
breeding.
➢ Major traits - flower color, fragrance, abiotic stress
resistance, disease resistance, pest resistance, manipulation
of the form and architecture of plants and/or flowers,
modification of flowering time, and post-harvest life etc.

RNAi (RNA INTERFERENCE)
➢ RNA interference (RNAi) is a sequence specific gene
silencing phenomenon caused by the presence of double
stranded RNA.
➢ Used as a knockdown technology.
➢ Analyze gene function in various organism
➢ RNAi targets include RNA from viruses and transposons.
4/22/2021 Department of FLA Singh et al. 44

4/22/2021 Department of FLA Napoli & Jorgrnsen, 1990 45

Timeline
Anderw Fire Craig Mello
1968
Crick & Orgel proposed
that RNA was the first
information molecule.
1990
Jorgenson with petunia
discovered gene silencing
1990-92
The human genome was
initiated & sequence
information began to increase
exponentially
2009
Ghidiya et al., discovered
different types of silencing
RNA
2009-2011
Invention related to various
drug discovery & therapettics.
1998
Fire & Mello coined the term
RNAi for gene silencing
mechanism performed by
dsRNA molecules in C.
elegans
2001
Hammond’s group
discovered RISC in
Drosophila melanogaster
1995
Guo & Kemphues discovered
that either sense or antisense
RNA could lead to gene
silencing while working on C.
elegans
2006
Fire & Mello won Nobel Prize
for discovering RNAi
mechanism
1972
Noller proposed the role of rRNA
in translation of mRNA into protein
molecules.
http://www.rnaiweb.com/RNAi/RNAi_Timeline)

Other name of RNAi
➢Co-suppression
➢PTGS
➢Gene Silencing
➢Quelling

Figure 18: RNAi Affecting Gene Expression
Bernstein et al., 2000 48

RNA
Coding RNA Non Coding
RNAs
mRNA
Constituent RNAs Regulatory RNAs
rRNAs
tRNAs
siRNAs miRNAs snRNAs
snoRNAs
Types of RNA involved in RNAi

COMPONENTS OF GENE SILENCING
• 1.Enzymes
• Dicer
• Drosha
• 2.RISC
• 3.RNA
• siRNA
• miRNA
• RdRp

DICER
➢ Endoribonuclease Dicer or helicase with
RNase motif
➢ Enzyme involve in the initiation of RNAi
➢ Rnase III family
➢ Recognise and cleaves double-stranded RNA
(dsRNA) and pre-microRNA (pre-miRNA)
into short double-stranded RNA fragments
called small interfering RNA and microRNA,
respectively.
➢ Dicer family proteins are ATP dependent
nucleases.
➢ Dicer facilitates the activation of the RNA-
induced silencing complex (RISC), which is
essential for RNA interference.
Bernstein et al., 2000 51

DICER’S DOMAINS
DICER’S DOMAINS
➢ Drosha :
➢ Core nuclease that executes the initiation step
of microRNA (miRNA) processing in
the nucleus
➢ Cleaves pri-miRNA, to form pre miRNA, which
is later processed by Dicer
Bernstein et al., 2000
Figure : One molecule of
the Dicer protein
from Giardia intestinalis;
RNase III domains are
colored green, the PAZ
domain yellow, the
platform domain red, and
the connector helix blue
➢ Both Drosha and Dicer can function as master
regulators of miRNA processing

RNA-induced silencing complex (RISC)
➢ Drosophila – Hammond
➢ Multi-protein complex –ribonucleoprotein
➢ Recognise and incorporate with one strand
of a single-stranded RNA (ssRNA)
fragment, such as microRNA (miRNA), or
double-stranded small interfering RNA
(siRNA)
➢ The single strand acts as a template for
RISC to
recognize complementary messenger RNA
(mRNA) transcript
➢ Activate Argonaute (a protein within
RISC) and cleave the mRNA.

Argonaute
➢ Active part of the RISC
➢ Binds different classes of small non-
coding RNAs, including miRNAs
and siRNAs and cleave the target
mRNA strand
➢ Endonuclease activity
➢ Responsible for selection of the
guide strand and destruction of the
passenger strand of the siRNA
substrate.
➢ Play a role in both triggering and
amplifying the silencing effect

RNA dependent RNA polymerase(RdRPs)
➢ RNA replicase
➢ Enzyme that catalyzes the replication of RNA from an RNA
template
➢ Transgenic plants show an accumulation of aberrant transgenic
RNAs, which is recognized by RdRPs and used as templates and
synthesize antisense RNAs to form dsRNAs
➢ dsRNAs formed are finally the targets for sequence specific
RNA degradation.
4/22/2021 Department of FLA Bernstein et al., 2000 55

miRNA (micro RNA)
➢ Non-coding RNA molecule
(containing about 22 nucleotides)
➢ RNA silencing and post-
transcriptional regulation of gene
expression
➢ miRNAs function via base-
pairing with complementary
sequences within mRNA molecules
➢ mRNA molecules are silenced
➢ (1) Cleavage of the mRNA strand
into two pieces, (2) Destabilization
of the mRNA through shortening of
its poly(A) tail, and
➢ (3) Less efficient translation of the
mRNA into proteins by ribosomes
Figure 19: miRNA biogenesis
Zhang et al., 2002 56

miRNA gene silencing
4/22/2021 Department of FLA Zhang et al., 2002 57

siRNA
➢ Small interfering - an integral role in the phenomenon of RNA
interference (RNAi), a form of post transcriptional gene silencing
➢ 21-25 nt fragments
➢ It interferes with the expression of specific gene
➢ Bind to the complementary portion of the target mRNA and tag
it for degradation preventing translation
➢ A single base pair difference between the siRNA template and
the target mRNA is enough to block the process.
4/22/2021 Department of FLA Zhang et al., 2002 58

siRNA gene silencing
4/22/2021 Department of FLA Elbashir et al., 2001 59

Scientia Horticulturae, 2014, 178: 1–7
Double flower formation induced by silencing of C-
class MADS-box genes and its variation among
petunia Cultivars
Siti Hajar Noor, Koichiro Ushijima, Ayaka Murata, Kaori Yoshida, Miki
Tanabe, Tomoki Tanigawa, Yasutaka Kubo, Ryohei Nakano
Graduate School of Environmental and Life Science, Okayama University, Japan

MATERIALS AND METHODS
➢Plant materials - Petunia (P. hybrida) seeds of cultivars ‘Fantasy Blue’,
‘Pico-bella Blue’, ‘Cutie Blue’ and ‘Mambo Purple’
➢Plasmid construction - Tobacco rattle virus (TRV)-based VIGS system
➢- pTRV1 and pTRV2 VIGS vectors
➢A cDNA fragment of petunia chalcone synthase, PhCHS - pTRV2 vector
to form pTRV2 PhCHS
➢Petunia C-class genes, pMADS3 and FBP6 - SmaI site of pTRV2 PhCHS
vector individually to generate constructs for silencing pMADS3 and
FBP6 separately
➢Silencing pMADS3 and FBP6 simultaneously, pMADS3 and FBP6
fragments were fused and cloned into the SmaI site of pTRV2 PhCHS
vector.
4/22/2021 Department of FLA Noor et al., 2014 61

Figure 20: Morphological changes in flowers of P. hybrida cv ‘Cutie Blue’
inoculated with pTRV2-PhCHS/pMADS3 and pTRV2-PhCHS/pMADS3/FBP6 (a,
b) VIGS-untreated control flower, stamens and a carpel (c, d) pMADS3-VIGS
flower, petaloid stamens and a carpel (e, f) pMADS3/FBP6-VIGS flower, petaloid
stamens and a carpel Scale bars = 1 cm.

Figure 21: Morphological changes in flowers of P. hybrida cv ‘Fantasy Blue’,
‘Picobella Blue’, and ‘Mambo Purple’ inoculated with pTRV2-
PhCHS/pMADS3/FBP6 (pMADS3/FBP6-VIGS). (a–c) ‘Fantasy Blue’; (d–f)
‘Picobella Blue’; (g–i) ‘Mambo Purple’; (a, d and g) VIGS-untreated control
flowers; (b, e and h) pMADS3/FBP6-VIGS flowers; (c, f and i) stamensand carpels
or converted new flowers of pMADS3/FBP6-VIGS flowers. Scale bars = 1 cm.

Figure 22: New flower formation in whorl 4 and from axil of whorl 3 in a double
flower of P. hybrida cv ‘Mambo Purple’ inoculated with pTRV2-PhCHS/pMADS3/FBP6
(pMADS3/FBP6-VIGS). (a) An opened double flower with a second new flower in
whorl 4 and an ectopic new flower emerging from the axil of whorl 3; (b) an opened
second new flower;(c) fused corolla (left), a carpel (center), and petaloid stamens (right)
of the second flower; (d) an ectopic new flower emerging from the axil of whorl 3; (e) an
unconverted stamen (left) and petal-like tissues of the ectopic new flower.

Figure 23: Average surface areas and average cell sizes of P. hybrida cv
‘Cutie Blue’ inoculated with pMADS3-VIGS) and
pMADS3/FBP6-VIGS

Figure 24: Modified ray florets of a transgenic chrysanthemum with
reduced chrysanthemum-AGAMOUS gene expression. The pistil of each
ray floret was changed to several corolla-like tissues (secondary corolla)
and a pistil-like tissue.
4/22/2021 Department of FLA Aida et al., 2008 66

Figure 25: Flower phenotype of wild type and dp mutant
(Insertion of an En/Spm‐related transposable element into a floral homeotic
gene DUPLICATED causes a double flower phenotype in the Japanese morning
glory)
4/22/2021 Department of FLA Nitasaka et al., 2003 67

Figure 26: Transgenic gerbera with MADS box genes. (a) 35S-gaga2
plant. (b) 35S-antisense gglo1 plant
4/22/2021 Department of FLA Yu et al., 1999
➢ Ray florets in transformants with antisense gerbera AGAMOUS formed
corolla-like organs in the third whorl, and all floret types formed carpelloid-
and pappus-like organs in the fourth whorl; however, they maintained floral
determinacy
68

CRES-T
➢ Chimeric REpressor gene-Silencing Technology
➢ Unique gene-silencing method
➢ Recently developed for the functional analysis of plant
transcription factors and for the genetic manipulation of plant
traits.
➢ A transcription factor is converted to a strong chimeric repressor
by fusion with a transcriptional repression domain, SRDX
➢ The chimeric repressor dominantly represses the expression of
target genes, even in the presence of redundant endogenous
transcription factors
➢ Result in a loss-of-function phenotype of the transcription factor
4/22/2021 Department of FLA Narumi et al., 2011 69

Plant Biotechnology, 2011, 28: 131–140
Arabidopsis chimeric TCP3 repressor produces novel
floral traits in Torenia fournieri and Chrysanthemum
morifolium
Takako Narumi, Ryutaro Aida, Tomotsugu Koyama, Hiroyasu Yamaguchi,
Katsutomo Sasaki, Masahito Shikata, Masayoshi Nakayama, Masaru
Ohme-Takagi2, Norihiro Ohtsubo
National Institute of Floricultural Science, Tsukuba, Ibaraki, Japan

MATERIALS AND METHODS
➢ Plant material - Torenia fournieri Lind. ‘Crown Violet’ and
Chrysanthemum morifolium Ramat. ‘Sei-Marin’ (Seikoen, Hiroshima,
Japan)
➢ Generation of transgenic plants - TCP3-SRDX, TCP3-mSRDX, and
TCP3-ox genes - introduce into the destination vector pBCKK
➢ Each transgene vector introduce into Torenia and chrysanthemum by
Agrobacterium-mediated transformation
➢ Transgenic plants regenerated - grown in the contained greenhouse
under natural light.
➢ Anatomical observation of floral organs - Fresh tissues were prepared
after the opening of flower buds and examined by scanning electron
microscope without fixing in order to observe petal and stigma
surfaces.

Figure 27: Phenotypic comparison of torenia flowers and leaves.
Narumi et al., 2011

Figure 28: Comparison of petal color and shape in transgenic torenia
plants.
Narumi et al., 2011 73

Figure 29: Phenotypic comparisons of chrysanthemum flowers and leaves.
Narumi et al., 2011

Figure 30: Comparison of corolla size, petal shape, and disk floret maturity
in transgenic chrysanthemum plants. . Bars = 1 cm.
Narumi et al., 2011 75

Figure 31: Morphological changes in the epidermal cells of TCP3-SRDX torenia petals

Figure 32: Expression of the TCP3-SRDX transgene in torenia and chrysanthemum. (A)
Total RNAs were prepared from petals of wild-type and TCP3-SRDX torenias
with type I, type II and type III phenotypes. (B) Total RNAs were prepared
from the leaves of wild-type and TCP3-SRDX chrysanthemums with type I and
type II phenotypes.

CONCLUSION
➢ Suppress endogenous TCP related activities in torenia and
chrysanthemum, without isolating and identifying their
sequences or target genes.
➢ TCP3-SRDX - chimeric repressors of development- and
differentiation-related transcription factors may have the ability
to modify petal colors and patterns in addition to petal size and
shape
➢ Modify cellular identity or positional information within the
petal.

Gene transfer methods
Indirect
➢ Agrobacterium
mediated gene transfer
➢ Most widely used
➢ More economical
➢ More efficient
➢ Transformation success
is 80-85%
Direct
➢ Particle bombardment
or micro projectile
➢ Direct DNA delivery
by Microinjection
➢ Ultrasonication
➢ Electroporation
4/22/2021 Chandler and Brugliera, 2011

4/22/2021
Figure 32: Gene transformation
Chandler and Brugliera, 2011

Future thrust
➢ Identification of flower shape mutant and development of
in-vitro protocol for their regeneration
➢ Most of the genetic modification for flower form is done in
Arabidopsis & Snapdragon only, it has be done in
commercially important crop
➢ Only few GM crop is released for commercial purpose,
i.e., Rose & Carnation (flower colour). Effort is to be done
to developed GM crop with modified flower architecture

CONCLUSION
➢ Creation of new flower shapes in ornamental plants is a
major breeding target as increase its commercial value.
➢ Flower shape including double flower can be developed by
different breeding techniques - hybridization, mutation,
polyploidy
➢ RNAi and CRES-T

THANK YOU

Breeding for different flower forms in ornamental crops

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