Breeding for polyploidy in ornamental cropsPresentation Transcript
DR. K.V. PRASAD
The presence of more than two paired sets
Numerical change in a whole set of
Triploid (3N), tetraploid (4N), pentaploid
(5N), hexaploid (6N)
The polyploidy is of two
more than two copies of a
two or more genomes and
each genome ordinarily present
in 2 copies
•within a species
•multiplication of the
same set of
• Induced artificially by
Traits in species , suited for
induction of polypoidy- by dewey
•Should have low CN
•Economic part should be vegetative.
•Should be cross- pollinated
•Should be perennial in habitat.
•Have ability to reproduce vegetatively.
Effect of polyploidy:
1.. Increased fruit weight, fruit size, seed size, crop
load, flower size etc.
2.. Reduction in fertility (in odd ploidy level individuals).
3.. Change in growth pattern.
4.. Can be used to create higher diversity.
5.. Greater ability to colonize new habitats than diploid
6.. increase blooming period
(marigold, Begonia, ageratum)
•Chromosome doubling after hybridization of 2
• Interspecific polyploidy
•Caused by hybridization followed by
chromosome doubling e.g., AABB, AABBCC
•To restore fertility in inter-specific crosses by
spontaneous doubling of chromosome
(Begonia, Impatians, Kalanchoe)
•Bears only one set of chromosomes
•Haploids of higher plants are sterile
•Producing pure homozygous lines for
•Such plants are developed through a
culture technique developed by Guha and
• Gynogenic haploids
Application in crop
-Tracing the origin of crop sps.
-Speciation & evolution
-Interspecific gene transfer.
-As a bridging cross
Polyploidy in ornamental crops:
CN from 2n=14 to 56
Early miniatures diploid, later
Hybrid teas and flouribundas
Sterility of some diploid
Interspecific hybrids arise
through genomic differences,
chromosome no may be
expected to increase fertility.
Thus sterile diploid R. rugosa x wichuriana ‘Max Graf’
spontaneously produced a tetraploid seedling, R. kordessi
Doubling of chromosome being tried
For sterile hybrids & diploid species to avoid production of
sterile triploids after cross with tetraploid cultivars.
Polyploidy induced in species & F1 interspecific hybrids by
colchicine to shoots of seedlings
The frequency of tetraploid was low
Chimerism complicating factor
In-vitro, controlled application of spindle inhibitoRS
South african species-diploid
Eurasian and central African
Sterile triploids and pentaploids
Indicates diploid-tetraploid and
Highest chromosome no
Some tripoids and pentaploids are
• x = 15 (2n=30 to 180)
•D. chinensis- tetraploid;
•D. gratianopolitanus- both
tetraploid and hexaploid
•Many desirable plant characteristics
related to plant ploidy levels
• Mixoploidy in several organs
from D. caryophyllus
• Positive correlation between
endopolyploidy, cell and petal size
•CN from 2x to 25x
•2n=36, 45, 47, 51, 75 by T.N. Khushoo
• Intraspecies and intrapopulation
variations in ploidy
•C. indicum - 2x,4x & 6x
•C. zawadskii - 4x & 6x
• Polyploids widely distributed
•Evolution & regulation of flower size of
large-flower population possible.
•evidence of low ploidy in large-flower
(2n=20 to 124)
•Mostly diploid, some polyploid also
•A.Andreanum, A.magnificum & A.
•A.digitatum & A.wallism –tetraploid;
•chloroplast number in the guard cell
convenient & reliable indicator of ploidy
level in anthurium.
•Micropropagation of A. scherzerianum
poses very little risk in ploidy changes
• 2n=32, others 2n=64
•Sorenson- 2n=32 species were
diploid and 2n=64 species
•Lawrence (1929) suggested that
the 2n=32 species were
allotetraploids, arising from hybrids
between now-extinct diploids with
•Garden dahlia (D. vŠ ariabilis)
with 2n=64, a hybrid that
combined the genomes of two
•It is an autoallopolyploid, rather
than an allooctoploid
•Tetraploid plantlets - slower
proliferation, higher vigour and
thickened broad leaves.
•Tetraploid plants developed larger
flowers, longer stalks, and have
•No of chloroplast present in the
stomata of guard cell is indicator
•Haploid use for development of new
• Important role in origin of new cultivars
in essential oil bearing plants.
•Spontaneous triploid in J. sambac & J.
autumnale(Sharma and Sharma), J.
grandiflorum( Murthy and Khanna)
• Spontaneous tetraploidy in
• Triploidy in J.grandiflorum increase
concrete content and thereby hold
promise as useful avenue for
improvement of this crop.
•Attempt to induce tetraploidy in
•Induced tetraploidy in J. grandiflorum
did not reveal superiority.
varieties in flower crops:
Rose –pusa mohini, aneuploid(3n+1)
Eva and J.G. Thornton-
Marigold –nugget, triploid
Zenith Mixed, triploid
Amaryllis -Samrat, tetraploid