Breeding of Potato and Sweet Potato

1. Potato
Botanical Name : Solanum tuberosum L.
Family : Solanaceae
Chromosome Number : 2n= 48
Origin : Tropical South America

2. Introduction
Potato is a very popular vegetable grown all over
the world and important food crop of grown more
than 100 countries in world.
Potato popularly known as ‘The king of
vegetables’, has emerged as fourth most important
food crop in India after rice, wheat and maize.
India is the third largest producer of Potato.
A raw potato is 79% water,
17% carbohydrates (88% is starch), 2% protein, and
contains negligible fat.

3. Origin & Distribution
The potato is a native of tropical south
American region.
It is believed that the cultivated potato
originated from its wild ancestors near the
lake Tritica basin in Peru Bolivian region in
high mountains.
The potato was introduced in India from
Europe in early 17th century.

5.  The genus Solanum comprises 8 cultivated species and 2000
wild relatives
 About 235 Solanum species tuberize
 73 % diploids, 4 % triploids, 15 % tetraploids , 2 % pentaploids
and 6 % hexaploids
 Triploids and pentaploids are highly sterile and maintained by
vegetative propagation.
 S.stenotomum , S.phureja & S.ajanhuioi are cultivated diploids
of which former two are sexually fertile while later one is less
fertile and yet bred true.
 S.chaucha & S.Juzepezukii are cultivated triploid, more or less
sterile.
 The cultivated tetraploid species S.tuberosum spp tuberosum &
S.tuberosum spp andigena are fertile.
 S.curtilobum is pentaploid.
 Nearly all the diploid species are self-incompatible while all the
tetraploids & hexaploids are self-compatible.

6. There are two major subspecies of Solanum
tuberosum:
Andigena, or Andean: The Andean potato is
adapted to the short-day conditions prevalent in
the mountainous equatorial and tropical regions
where it originated.
Tuberosum, or Chilean: The Chilean potato is
native to the Chiloé Archipelago, is adapted to the
long-day conditions prevalent in the higher latitude
region of southern Chile.

7. Breeding Objectives
1.High tuber yield : Yield of tubers is decided by number of
tubers, tuber size and distribution of tuber.
2.Earliness
3.Photoperiod insensitivity
4.Responsiveness to fertilizer
5.Breeding for varieties having better morphology of tuber:
Better morphology of tuber is determined by Eye depth,
flesh colour, Growth cracks, Hollow heart, Shape, Skin colour
6.Better keeping quality – resistance/tolerance against
shrinkage, rottage, accumulation of sugars, specially reducing
sugars and reasonable dormancy.

8. 7. Better quality of tubers:
•Round, medium sized with shallow eyes and free from greening
for general consumption.
•High vitamin C and protein content
•High specific gravity (dry matter content) suitable for French
fries, chips and dehydrated products
•Low sugar content for chips and french fries to avoid browning.
8. Resistance to - Late blight, Early blight, Charcoal rot, Wart,
Common scab, Bacterial wilt, Softrot, Viral diseass and
Nematodes
9. Resistance / tolerance to aphids, potato tuberworm
10. Resistance/ tolerance to heat, drought, frost and soil salinity
11.To extend potato cultivation in non-traditional areas there is
need to develop heat tolerant genotypes.
12. Varieties for improved processing attributes.

9. Breeding methods
Potato is a self pollinated crop but is vegetatively
propagated. The cultivated tetraploid varieties are highly
heterozygous. Most of them are also pollen sterile. Selfing or
inbreeding in potato leads to loss of vigor of the progeny and
non-flowering. Hence the conventional method or pure line
method of breeding is generally not practiced.
Hybridization and selection: Being vegetatively propagated,
breeders take advantage of selecting and multiplying genetically
identical individuals in the succeeding generations.
Backcross method: Cultivated potato does not posses
resistance to most of the diseases and pests. Resistance genes
are mostly found scattered in wild and semi-cultivated species
available in centre of origin and diversity in south America.
However, transfer of the resistant genes from wild species into
cultivated potato is a difficult task.

10. Biotechnology:
Tissue culture technology has been widely used
for production of disease free & quality planting
material.
CPRI (Central Potato Research Institute), Simla
has developed trangenics using cryIab & asmotion
gene for resistance against potato tuber moth &
late blight disease.
CPRI in collaboration with JNU, New Delhi
developed eight indian varieties using AmAI
(Amaranth seed albumin) gene for increase in total
protein content.

12. Indigenous and exotic potato varieties/samples in
India
Indigenous varieties/samples Salient features
Agra Red, Chamba Red, Coonoor
White, Coonoor Red, Darjeeling Red
Round, Desi, Dhantauri, Gola Type A,
Gola Type B, Gola Type C, Phulwa,
Phulwa Purple Splashed, Red Long
Kidney, Sathoo, Shan and Silbilati
Heat and drought tolerant, therefore
cultivated predominantly in the Indian
plains; tolerant to degenerative
viruses; due to physiological
advantage can be stored in country
stores during hot Indian summers
Exotic varieties Salient features
Ally, Arran Counsal, Ben Cruachan,
Craig’s Defiance, Dunbar Cavalier,
Great Scot, Italian White Round, Late
Carman, Magnum Bonum, Majestic,
Northern Star, President, Raeburn’s
Gregor Cups, Red Rock, Royal Kidney
and Up-to-Date
Long-day adopted; therefore suitable
for the Indian hills only; multiplication
was characterized with progressive
accumulation of degenerative viral
diseases; physiological limitation on
tuber storage and utilization in hot
Indian summers

13. Varieties
Potato varieties are primarily distinguished based on their habit, Pigmentation on
the stem,stucture of leaf, flower and fruit colour and tuber characters like shape,size
and colour. Some of the varieties under cultivation at present are
Kufri Badshah(Kufri jyoti x Kufri Alankar):
The variety was released in 1979 for north indian plains and plateau region.it is a
medium maturing(90-100 days) variety producing tall,erect,medium compact and
vigorous plants with white flowers. The variety possesses resistance to late blight
,early blight and potato virus and has an average yield of 32-35 tonnes/ha.
Kufri sindhuri(Kufri Red x Kurfi kundan): The variety was released in 1967
for cultivation in north Indian plains particularly for Eastern Uttar Pradesh and Bihar
where red tubers were preferred. It is a late maturing(120-140 days) variety
producing tall,erect,open and vigorous plants with flower of light-red-purple colour
with white tips.it is moderately resistant to early blight with an average yield of 30-
35 tonnes/ha.
Kurfi chandramukhi(sd:4485 x Kurfi kuber): The variety was released in
1968 . It is an early maturing (75 days). Tubers are lerge ,white,oval,flattened with
shallow eyes. The variety has an average yield of 23-25 tonnes/ha.

14. Kufri jawahar (Kufri neelamami x Kufri jyoti): The variety
was released in 1996 for Punjab,Harayana,plateau region of
Madhya Pradesh,Gujarat and Karnataka. It is a medium
early maturing(80 days) variety producing short ,erect,
compact, and vigorous plants with white flowers. The
variety is moderately resistant to late blight and has an
average yield of 28-30 tonnes/ha.
Kurfi pukhraj ( raigs defiance x JEX/B-687): The variety was
released in 1997 for Punjab,Uttar pradesh,Madhya
pradesh,Karnataka,Gujarat and Maharashrta. It is a medium
maturing(90-100 days) variety producing tall,semi-
erect,medium compact and vigorous plants with white
flower. The variety is resistant to early blight and
moderately resistant to late blight and has an average yield
of 30-35 tonnes/ha.

15. Central Potato
Research Institute
(CPRI) , Shimla,
Himachal Pradesh
International Potato Center, Lima, Peru
• All varieties released by the CPRI carry the prefix ‘KUFRI’ as a memento to the place of
hybridization.

16. Sweet potato
Ipomoea batatas
2n = 6x = 90
Scientific classification
Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Solanales
Family: Convolvulaceae
Genus: Ipomoea
Species: I. batatas
Binomial name
Ipomoea batatas
(L.) Lam
Centre of Origin: Central or South America.

17. Importance
Sweetpotato (Ipomoea batatas (L.) Lam.) is an
outcrossing hexaploid that is cultivated in the tropics
and warm-temperate regions of the world.
 Its large, starchy, sweet-tasting, tuberous
roots are a root vegetable.
The young leaves and shoots are sometimes eaten
as greens.
The sweet potato is only distantly related to
the potato (Solanum tuberosum) and does not
belong to the nightshade family, Solanaceae, but
both families belong to the same taxonomic order,
the Solanales.

18. Origin and Distribution
Sweet potato was domesticated in tropical Central America about
6000 BC.
It is cultivated in the tropics and warm- temperate regions of the
world.
Ipomea trifida is the most likely diploid ancestor of cultivated
sweet potato and it forms polyploidy complex with a series from
diploid to hexaploid. This crop is an autohexaploid.
Polyploidy is recognized as an important factor in the evolution and
diversification of plants.
Of the approximately 50 genera and more than 1,000 species of
Convolvulaceae, I. batatas is the only crop plant of major importance
—some others are used locally, but many are poisonous.
Sweet potato (Ipomoea batatas) is a polyploid, and is the only
hexaploid species (6x = 90, x = 15) in section Batatas of the family
Convolvulaceae.
The basic chromosome number x=15. And there are also diploids
(2n=2x=30) and tetraploids (2n=4x=60).

19. Species, ploidy level, origin and accession availability at the
International Potato Center (CIP) of Ipomoea section Batatas.

20. CULTIVARS
In India, Sweet Potato is used as a subsidiary food
and as industrial raw material for production of
starch, alcohol and pectin. However, it is mostly used
for human consumption.
There are two broad categories of sweet potato:
• The staple type with white flesh and white or
purple skin has a high starch and dry- matter
content.
• The dessert type with orange flesh and orange
skin with a high sugar and beta-carotene content.

21. Commonly three distinct types of sweet potato available for
commercial production include:
1) Orange/copper skin with
orange flesh
2) Red/purple skin with
cream/white flesh
3) White/cream skin with
white/cream flesh

22. Breeding Objectives :
1. Breeding cultivars for table use – good eating quality, good appearance. Eating quality is
affected by two main factors, namely sweetness and texture.
2. Breeding cultivars for processed foods
Breeders have developed cultivars that have a high content of beta-carotene and
anthocyanin, which are suitable as natural food colorants, flours, juices and pre cooked foods.
Sweet potato cultivars with purple flesh color containing anthocyanin for processed foods are
recognized broadly as the health promoting foods.
3. Breeding cultivars for industrial raw materials of alcohol and starch
Imo shochu is a traditional spirit made from the sweet potato and is popular with
consumers in Japan. The leading variety used as a raw material of alcohol production is
‘koganesengan’. This cultivars exhibits high yield, wide regional adaptability and is
multipurpose.
4. Breeding for high yield
It is found that number of tubers per plant and petiole length should be the selection
criteria of high yielding Sweet potato clones.
5. Breeding for good keeping and cooking quality of tubers
6. Breeding for high protein content
7. Breeding for abiotic stress resistance
8. Breeding for resistance to pests and diseases
a) stem rot
b) Black rot
c) Southern root nematode

23. Most varieties of Sweet Potato show self and cross incompatibility, low natural flowering
ability and low seed fertility. This out crossing, polyploidy and vegetative propagation in sweet
potato, causes high heterozygosity and variability in the genetic background of this crop.
Breeding Methods :
The breeding methods adopted for improvement of sweet potato are clonal selection, mass
selection, polycross and pedigree method of selection in crossed progenies of selected
clones. Spontaneous and induced mutations have also contributed to its variability besides
cross pollination which has been utilized in breeding.
1. Selection :
 The incompatibility system in Sweet Potato offers to maintain high level of heterozygosity
and thus provides ample scope of selection even among the collection of local cultivars.
Selection criteria includes characters like high yield potential, adaptability, acceptable
qualities and resistance to major pests and diseases.
 The germplasm has to be evaluated critically for various agronomic characters and
compatibility groups for further utilization in the breeding programme or for direct selection.
Thus among the indigenous cultivars, superior lines include cross-4, cross-5, s-30,c-43,
Kalmegh, kanhangad local etc.
Out of which kanhangad local with compact plant type, high yield and better tuber
quality(25 % starch) has been selected which is suited to both upland and low land condition
and there by adopted in recombination breeding.
Among the exotic genotypes, acclaimed lines include Centennial, and 'Triumph' from USA;
and ‘ Norin ' from Japan.

24. 2. Hybridization :
 The initiation of sweet potato breeding involves the selection of
crossing parents from the genetic resources and cross combinations.
Most varieties of Sweet potato can produce few or no flower in
temperate regions and they show the self- and cross-incompatibility.
Therefore, Sweet potato breeders utilize breeding processes such as
grafting for flower induction and the identification of incompatibility
groups before crossing to overcome these problems.
The top grafting method using morning glory stocks is adopted to
induce flowering.
A dwarf type of Japanese morning glory, Ipomoea nil is used as a
rootstock for two reasons: one has a thick stem, which makes grafting
manipulations easier, and it also has a long flowering period that
increases the total number of flowers.
The sweet potato scions form flower buds in 3 weeks after grafting
and continue to flower for more than 2 months.
Eg. Sankar, Rajendra Sakarkand 5 (X 5), H 85-16 (Gouri)

25. Inter varietal Hybridization :
It offers immense possibilities for producing
genotypes with high variability. High yielding
parents are carefully selected and used in the
hybridization programme for combining the
desired traits.
The yield potential of the progenies is assessed
through continuous evaluation and selection.
As a result two hybrids H.41 & H. 42 were
identified at CTCRI, earlier and of late H.268
showed its superiority over all the hybrids evolved.

26. 3. Biotechnology :
Genetic transformation could enhance yield, nutritional value and tolerance to stress. Transgenic
sweet potatoes tolerant to biotic and abiotic stress, improved nutritional value and higher yields
have been developed.
1.Sweet potato expressing the endotoxin cry8Db, cry7A1 and cry3Ca genes showed lower sweet
potato weevil infestation than non-transformed lines.
2. Transgenic cultivar 'Xushu18' expressing the oryzacystatin-1 (OC1) gene showed enhanced
resistance to sweet potato stem nematodes.
3.Sweet potato line 'Chikei 682-11' expressing the coat protein (CP) exhibited resistance to the
sweet potato feathery mottle virus (SPFMV).
4.Transgenics expressing the rice cysteine inhibitor gene oryzacystatin-1 (OC1) also exhibited
resistance to the SPFMV.
5.Transgenic cultivar 'Kokei' expressing the spermidine synthetase gene FSPD1 had higher levels of
spermine in the leaves and roots, and displayed enhanced tolerance to drought and salt stress.
6. 'Shangshu' variety expressing the IbMas has shown enhanced tolerance to salt stress.
7.Transgenic 'Lixixiang' expressing IbMIPSI showed an up-regulation of metabolites involved in
stress response to drought, salinity and nematode infestation
8. Transgenic 'Yulmi' sweet potato transformed with copper/zinc superoxide dismutase (CuZnSOD)
gene showed an enhanced tolerance to methyl viologen induced oxidative and chilling stress.
9.Similarly, transformation of cultivar 'Sushu-2' with betaine aldehyde dehydrogenase (BADH) gene
resulted in transgenics tolerant to salt, chilling and oxidative stress
10.Sweet potato varieties 'Kokei14' and 'Yulmi' transformed with the bar gene were shown to be
tolerant to application of the herbicide Basta.

27. Varieties
 Pusa safed: This is a high yielding selection from a china type FA-17 - white, released
from Pusa Research station, Bihar. This has a white skin and flesh. Tubers are long, the
flesh after cooking becomes creamy- white, sweet and highly palatable. The tubers can be
stored well. it has wide adaptability and performs well in Bihar, Uttar Pradesh & Tamil
Nadu.
Samart (S-30): This is a selection made by the Andhra Pradesh Agricultural University. It
is a Photo insensitive type and hence can be successfully cultivated both in the Kharif
and summer season. Leaf is dark-green with purplish veins, succulent. Plant growth is
vigorous, having early bulking capacity and is a heavy yield. The yield ranges from 20-22
t /ha. Tubers can be harvested from 90th day onwards. The tuber skin is white pinkish
streaks; It is moderately tolerant to drought conditions.
Varsha: It is released for Maharashtra suitable for rainy season. It is the high yielding
( 150 q/ ha). it belongs to the group varieties of sweet potato.
Konkan Ashwini: A sweet potato variety Konkan Ashwini is released for cultivation in
Maharashtra. It is a short duration, dual seasonal and high yielding variety.
Centennial: Centennial is a per-domestic clone North Caroline in USA. It is a high
yielding cultivar, with high quality. However, it is susceptible to root-knot nematode and
soil rot diseases.
Xushu-18: Xushu-18 has been selected from china. It is considered to be a high yielding,
disease resistant, multipurpose variety with wide adaptation and acceptability.

28. Central Tuber Crops Research Institute (CTCRI)
Sreekariyam, Thiruvananthapuram, Kerala