improvement of crop

2. Role of Amphidiploids
 Allopolyploidy
An allopolyploid resulting due to doubling of
chromosome number in sterile hybrid derived from
hybridization between two unrelated diploid species is
sometimes also called ‘amphidiploid’.
Production of triticale from a cross of hexaploid wheat
(AABBDD; 2n=42) and diploid rye (RR; 2n=14).
The hybrid would have 28 chromosomes which gave rise
to octoploid (2n=56=28II) triticale.

3.  Another amphiploid was derived, as early as 1892, from
a sterile hybrid produced from a cross between
Anemone sylvestris (2n=16) and A. Multifida (2n=32).
 This amphiploid had 2n=48 and formed 24 bivalents at
meiosis.

4. Synthesis of New Genera and Species
 Allopolyploids originate in nature through interspecific or
intergeneric hybridization followed by chromosome
doubling.
 This process has been considered to be a device to
generate new species.
 Since this procedure can be repeated in the laboratory, it
has been used for the synthesis of new genera and
species.

5.  Although, a large number of amphiploids (particularly in
Triticeae) have been artificially produces, the most
important example in this connection is triticale (X tritico
secale), which is now used as a commercial crop in
several countries, occupying an area of several million
hactares.

6. Raphano brassica and X brassico raphanus
 The well known amphidiploid Raphano brassica
(2n=36=18II=PRCC) was obtained by Karpechenko
(1928), due to spontaneous chromosome doubling of
Hybrids between Raphanus sativus (2n=18=9II=RR) and
Brassica oleracea (2n=18=9II=CC).
 Subsequently, it was obtained artificially by several
workers and the common name ‘radicale’ was suggested
(like ‘triticale’ for X Triticosecale).

7. Aritificial synthesis of Raphanobrassica

8.  For many years, Raphano brassica was only a curiosity
and model example of a true allopolyploid or an
amphidiploid, but without any practical utility.
 The improved strains were more vigorous and fertile and
also had resistance to club root and powdery mildew, the
two important diseases.

9.  In recent years a number of strains of rapradish
(Xbrassicoraphanus, 2n=38=AARR) from the
cross B. rapa (syn. B. campestris) X R. sativus
have also been synthesized.
 The initial population of this amphiploid was
subjected to breeding, leading to improvement in
fertility and nematode resistance.

10.  Galeopsis tetrahit
G.tertahit (2n=32), synthesized from the cross, G. pubescens
(2n=16) X G.speciosa (2n=16), was perhaps the first example
of an atificially synthesized amphidiploid as a new species.
 Primula kewensis
P.Kewensis (2n=36) was obtained from a 4x branch of a 2x
hybrid between P.florifunda (2n=18) and P. verticillata (2n=18).
Subsequently. It could be obtained by crossing these two
species and doubling the chromosome number in the sterile
F1 hybrid.

11.  Aegilotricum
Aegilotricum (2n=56=AABBDDNN) is the name given to an
amphiploid derived from the cross Aegilops ventricosa
(2n=28=DDNN) X Triticum turgidum (2n=28=AABB), and has
been used for the transfer of resistance against the disease
‘eyespot’ from Ae ventricosa to wheat.
 By repeated crossing of this amphiploid with wheat, new
resistant cultivar of wheat, namely ‘Roazon’ was produced.
 However, Aegilotricum (2n=70=AABBDDDDNN), involving
hexaploid wheat in the initial cross, could not be produced.

12. Agrotricum
Agrotricum was obtained as an amphiploid from a cross
Agropyron intermedium (2n=42=E1E1E2E2NN) X
Triticum aestivum (2n=42=AABBDD).

13.  Their vigor and fertility were however low. However, by
backcrossing the F1 hybrid with 6x wheat, a partial
amphiploid, namely TAF 46, was obtained which had
2n=56 AABBDDXX (where X is a new reconstructed
genome having chromosomes from E1, E2 and N
genomes.)
 This partial amphiploid was later used for getting alien
addition lines for A. intermedium chromosomes to wheat,
which were successfully utilized for transfer of resistance
against the rusts to wheat.

16.  The hexaploid triticales, which are initially produced as
amphiploids are called primary triticales.
 These primary triticales have many drawbacks like
shrivelled grains, meiotic instability, poor yield and
preharvest sprouting.
 For further improvement, these primary triticales are
regularly intercrossed among themselves with hexaploid
triticales.
 General methods for improvement of these by
backcrosses shown in fig.

17.  It will be seen that the improved triticales can be either
recombined triticales or secondary triticales, the latter resulting
due to crosses with 6x wheat or 8x triticales.
 It is these secondary triticales which are being released as
cultivars in different parts of the world.
 It will be seen that in India also in 1982 a cultivar TL 419 was
released by Punjab Agricultural Univeristy (PAU), Ludhiana, on
a regional basis.
 After the release of TL 419, even better strains giving yields
higher than TL 419 could be produced.

18. A New Synthetic Amphiploid (AADDAA) between Gossypium
hirsutum and G.arboreum Lays the Foundation for Transferring
Resistances to Verticillium and Drought
 Cross-incompatibility of G. hirsutum (2n = 52, AADD) and G. arboreum (2n = 2x
= 26, AA)
 MSB2K supplemented with 0.5 mgl-1 kinetin and 250 mg-1 casein hydrolysate is
an efficient initial medium for rescuing early (3 d after pollination) hybrid embryos
 Four putative hybrid plants were successfully chromosome-doubled by
treatment with 0.1% colchicine for 24 h and become amphiploid, which were
confirmed by cytological observation, self-fertilization and backcrossing
 Resistance at seedling stage indicated that the synthetic amphiploid
showed highly resistant to Verticillium and drought.

19.  The interspecific hybrid plants were preserved and
propagated by grafting.
 The stem apices of vegetative branches from these
hybrid plants were immersed in 0.05, 0.10, 0.15 and
0.20% (w/v) colchicine solution for 24, 36 and 48 h and
grown in ceramic pots under natural conditions.

22. Generation of the amphiploid
 Generation of the amphiploid obtained by doubling chromosome complements in
interspecific F1 hybrids between G. hirsutum and G. arboreum
 The putative hybrid F1 plants, which were confirmed by cytology, molecular markers
and morphological observation, were treated with different concentrations of
colchicine for 24, 36 and 48 h.
 The results show that among 30 plants treated with 0.1% colchicine for 24 h,
22.22% (four out of 18 plants survived, while 12 died) of interspecific hybrid F1
plants exhibited gigantism and had improved fertility, and they set bolls and
produced several seeds.
 To understand why these plants produced seeds, we collected young flower buds
from these plants and observed their chromosome associations. The results indicate
that the number of univalent significantly decreased while the numbers of bivalents
and multivalents greatly increased even if there were too many chromosomes to
discriminate, which suggests that these plants were chromosome-doubled and
were therefore putative amphiploids, i.e.,hexaploids. Therefore, to further verify the
genome components of the putative amphiploids, S1 plants derived from the putative
amphiploids by self-pollination were used to identify chromosome numbers by GISH
using somatic mitotic cells of the root tips.
 The results demonstrate that their genome components contained four sets of A
genome (red signals) and one set of D subgenome (blue signals) and had a total of
78 chromosomes, i.e., 2n = 6x = AAAADD = 78, which further confirms the

23. Screening for drought tolerance

24. Screening for verticillium wilt

25.  S1 progenies derived from the hexaploids self-pollinated were
assessed for resistance to VW and drought.
 The preliminary results demonstrated that S1 has the potential for
transferring resistance genes from
G. arboreum into G. hirsutum by backcrossing.
 And these hexaploid plants were also backcrossed with G. hirsutum
(TM-1) and have produced enough backcrossing seeds.
 These backcross progenies will be consecutively backcrossed with
G. hirsutum for 4~5 times, which would allows them to develop G.
arboreum-introgressed lines with the uniform genetic background of
TM-1 by molecular marker-assisted selection.
Finally the evaluated lines will be released with resistance to VV and
drought tolerance.

26. Identifying desirable traits in natural
populations
 Selection of desirable plants in the hotspot location
 Endemic area
 Artificial screening

27. Cotton useful traits
S.No Name Breeding value
1. G.armourianum Resistance to white flies, jassids and bacterial leaf blight
2. G.aridum Resistance to reniform nematode and salinity tolerant
3. G.raimondii Resistance to jassids
4. G.gossypioides Resistance to cotton leaf curl disease
5. G.anomalum Resistance to cotton wilt, angular leaf spot,drought tolerance, high
fibre quality.
6. G.sturtianum Resistance to Fusarium wilt
7. G.robinsonii Resistance to Fusarium wilt
8. G.tomentosum Resistance to jassids and thrips

28. Redgram
 Cajanus scarabaeoides: Resistant to wilt, sterility mosaic
disease (SMD), phytophthra blight, pod borer, podfly, cyst
nematode and possesses combined resistance to diseases
and insects, water logging tolerance and high seed protein
(>28%).
 Cajanus platycarpus: Resistant to phytophthora and
alternaria blight, salinity tolerance, photoperiod insensitivity,
extra early flowering and high seed protein (27-31.6%)
 Cajanus albicans: Resistant to SMD, alternaria blight,
drought and salinity tolerance, high seed protein (>30%).
 Cajanus sericeus: Resistant to SMD, phytophthora blight and
alternaria blight, drought tolerance, high seed protein content
(>29%)

29. Tomato
2
9
• Charles Rick (1915-2002) who dedicated his life to discover, collect
and characterize exotic tomato germplasm
• Today >83,000 tomato acc. are stored in seed banks worldwide,
ranking 1st among vegetable species collected (FAO 2010)
• Main collections in world: Tomato Genetic Resources Center in
California (TGRC), USDA2 collection, World Vegetable Center in
Taiwan
Many tomato disease resistances introgressed from wild species, mostly
from Lycopersicon pimpinellifolium Mill
• Since 1982 one per year with virtually all disease resistance genes
currently in commercial cultivars having been bred from wild genetic
resources.
• Over 40 resistance genes have been derived from Lycopersicon
peruvianum, L. cheesmanii, L. pennellii, and several other wild relatives

30. • Bemisia tabaci is one of the most threatening pests in in Solanaceous
crops such as tomato and pepper
• Pesticide application is often not effective and hazardous
• The exploitation of plant natural defenses that are present in wild
relatives of tomato, may offer a solution.
• Screened 46 accessions of tomato and related wild species
3 methods of screening; (1)a free-choice test in a screen-house
(Indonesia), (2) a no-choice test with clip-on cages in a greenhouse and
(3) a leaf disc test in a climate-room
• Antibiosis resulting in low adult survival was the major component
for resistance in tomato
• Whitefly non-preference and resistance were associated with the
presence of type IV trichomes
3
0

31. Important genes in wheat found in related species
System-wide Genetic Resources Program (123
996)

32. The Genus Oryza : Broadening the Gene Pool of Rice—
Exploitation of Diversity of the Wild Species Germplasm
24
Paul et al (2014) Genetics and Genomics of Rice

33. Genus oryza: 12 representative species
IRRI Rice Gene Bank and The National Institute of Genetics’ Oryza base,
combined, maintain >4,000 acc. of wild Oryza species and 1,500 cultivated
O . glaberrima acc. 3
3

34. 3
4

35. 3
5

36. 3
6

37. Potato late blight resistance
• Best resistance source for potato late blight are Solanum demissum
and S. stoloniferum.
• Currently 40% of the total area of the most popular potato cultivars
in US have S. demissum in their ancestry (National Potato Council
2003),
• Along with these wild relatives, S. chacoense, S. acaule, S. vernei and
S. spegazzinii have provided resistance to several viruses and pests
3
7

38. 3
8

39. Wild Cicer species with resistance to various biotic and abiotic
stresses
3
9

40. Yield improvement
4
0
• In backcross progeny derived from crosses of two indica rice varieties
(IR64 and IR55423-01) with O . glaberrima:
1. Two new QTLs for grain yield per plant ( ypp2 . 1 and ypp4 . 2 )
2. In IR55423-01 × O . glaberrima , 11 new QTLs for biomass
identified
• Alleles associated with the yield-related traits, such as spikelet
number, grain weight, and panicle length, were identified in this O .
rufipogon accession using a BIL population derived from a cross with
Zhenshan 97B

41. 4
1
Contd…
• Rice cultivar NSICRc112 released in the Philippines in 2002 from
Oryza sativa and O. longistaminata (Brar 2005)
• Synthetic hexaploid (SH) wheats; cross between durum wheat and
the wild relative Aegilops tauschii that has undergone artificial
chromosome doubling (hexaploid)
• These lines are then back-crossed to elite bread wheat cultivars, to
produce wheats with superior quality, disease resistance and yield.
• In 2003, ‘Chuanmai 42’, cross between an SH and a local cultivar,
released in China, producing 20–35% higher yields (CIMMYT 2004).
• Pyramiding of three independent yield-promoting genomic regions
introduced from Solanum pennellii, has led to hybrids with a 50%
increased yield over a leading variety (Gur and Zamir 2004)

42.  High yielding ILs (IL50-7) derived from BC3F2-F8 of cross KMR3
x O. rufipogon (major yield QTL yld2.1), control KMR3
 Aim: Comparing global gene expression of flag leaf and young
panicle of IL50-7 with those of recurrent parent KMR3. Such a
comparison would lead to discovery of novel yield-related
genes/alleles from wild rice
4
2

43. ;
Four crosses, ILC 482 (C. arietinum) x ILWC 179 (C. echinospermum) ILC
482 x ILWC 124 (C. reticulatum) and their reciprocals
F1
F2
Selected 22 F7 lines
International Center for Agricultural Research in the Dry Areas (ICARDA), Syria, from 195
83 7-95

44. • In India Mulbery (Morus) is represented by four species i.e., M.indica L.,
M.alba L., M.laevigata and M.serrata
• Central Silk Board developed improved mulberry varieties through
conventional, polyploid and backcross breeding.
• Though varieties have more leaf yield/ quality aspects but in long term this
may not be suitable for specific condition. To bring greater diversity into the
breeding pools, it requires introduction of unadapted and productive exotic
or wild species
• M. serrata: possess several agronomically important traits such as higher
leaf thickness, greater leaf moisture content, moisture retention and
resistance to abiotic and biotic stresses (drought and frost)
• M. laevigata: bigger leaf size, higher leaf thickness, moisture retention,
resistance to biotic and abiotic stress (drought, saline and frost)
• They have scope for introgression breeding between wild and cultivated
species 4
4

45. • IARI released ‘BG1103’ a drought and temperature tolerance
chickpea variety derived from Cicer reticulatum, is a leading
cultivar (40% more yield) in Northern India
• Oryza rufipogon genes have been exploited for tolerance to
high acidic-sulfate content soil in Vietnam
• O. longistaminata genes for drought tolerance in cultivars of
Philippines, allowing the spread of rice production to
previously unusable lands
Introgression for Tolerance to Abiotic Stresses
4
5

46. 4
6