GOOD

1. Wide Hybridization
PRAKASH.A.R
2017601603
M.SC (PGR)

2. Introduction
 Hybridization
Crossing between two genetically dissimilar parent is called hybridization.
 Distant hybridization
Hybridization between individuals from different species belonging the same
genus (interspecific hybridization) or two different genera of same family
(intergeneric hybridization) is termed as distant hybridization and such crosses are
known as distant crosses or wide crosses.
 This because individuals used for hybridization in such cases are taxonomically
more distantly related than different variety from the same species.

3. History
 Thomas Fairchild (1717)
The first authentic record of a distant hybridization for crop improvement is the
production of a hybrid between Carnation (Dianthus caryophyllus) and Sweet
willian (Dianthus barbatus).
 Karpechenko (1928)
An intresting intergeneric hybrid, Raphanobrassica, was produced.
 Rimpu (1890)
Produce the first intergeneric hybrid triticale which have greater potential than
raphanobrassica.

4. Interspecific combinations of wheat and rye that
produces hexaploid and octaploid triticale

5. Main features of Interspecific or Intergeneric hybridization
1. It is used when the desirable character is not found within the species of a crop.
2. It is an effective method of transferring desirable gene into cultivated plants from
their related cultivated or wild species.
3. It is more successful in vegetatively propagated species like sugarcane and potato
than in seed propagated species.
4. It gives rise to three types of crosses viz. a) fully fertile, b) Partially fertile and c) Fully
sterile in different crop species.
5. It leads to introgression which refer to transfer of some genes from one species into
genome of another species.
6. F1 hybrid between two genus are always sterile. The fertility has to be restored by
doubling of chromosome through colchicine treatment.

6. Problems associated with wide crosses
The major problems associated with wide crosses are:
• Cross Incompatibility
• Hybrid In viability
• Hybrid Sterility
• Hybrid Breakdown

7. CROSS INCOMPATIBILITY
• This is the inability of the functional pollen grains of one species or genus
to effect
• fertilization in another species or genes.
There are three main reasons of cross incompatibility viz.
I. Lack of pollen germination,
II. Insufficient growth of pollen tube to reach ovule
III. Inability of male gamete to unite with the egg cell

8. HYBRID BREAKDOWN
• Hybrid breakdown is a major problem in interspecific crosses.
• When F1 hybrid plants of an interspecific crosses are vigrous and
fertile but there F2 progeny is weak and sterile it is known as hybrid
breakdown.
• Hybrid breakdown hinders the progress of interspecific gene transfer.
• This may be due to the structural difference of chromosomes or
problems in gene combinations.

9. HYBRID INVIABILITY
• This refers to the inviability of the hybrid zygote or embryo. In some cases,
zygote formation occurs, but further development of the zygote is arrested.
In some other cases, after the completion of the initial stages of
development, the embryo gets aborted.
The reasons for this are:
1. Unfavorable interactions between the chromosomes of the two species
2. Unfavorable interaction of the endosperm with the embryo.
3. Disharmony between cytoplasm and nuclear genes

10. HYBRID STERILITY
• This refers to the inability of a hybrid to produce viable offspring. This is more
prominent in the case of intergeneric crosses. The major reason for hybrid
sterility is the lack of structural homology between the chromosomes of the
two species.
• This may lead to meiotic abnormalities like chromosome scattering,
chromosome extension, lagging of chromosome in the anaphase, formation of
anaphase bridge, development of chromosome rings and chains, and irregular
and unequal anaphase separations.
• These irregularities may lead to aberrations in chromosome structure. Lack of
homology between chromosomes may also lead to incomplete pairing of
chromosomes.

11. TECHNIQUES TO MAKE WIDE CROSSES SUCCESSFUL
1.SELECTION OF PLANTS
The most compatible parents available should be selected for the crosses.
2. RECIPROCALCROSSES
Reciprocal cross may be attempted when one parental combination fails. e.g.
Mung x udid- cross compatible and Udid x mung-cross incompatible
3. MANIPULATION OF PLOIDY
Diploidization of solitary genomes to make them paired will be helpful to make
the cross fertile.
4. BRIDGE CROSSESS
When two parents are incompatible, a third parent that is compatible with both the
parents can be used for bridge crosses and thus it becomes possible to perform cross
between the original parents. e.g.Tobacco
Nicotiana repanda x N.tabaccum– cross incompatible
Nicotiana repanda x N.sylvestris- cross compatible
Nicotiana syivestris x N.tabaccum- cross compatible

12. 5. USE OF POLLEN MIXTURE
Unfavorable interaction between pollen and pistil in the case of wide crosses
can be overcome to some extent by using pollen mixture.
6. MANIPULATION OF PISTIL
Decapitation of the style will sometimes prove helpful in overcoming
incompatibility.
7. USE OF GROWTH REGULATORS
Pollen tube growth can be accelerated by using growth hormones like IAA,
NAA, 2,4-D and Gibberellic acid.

13. 8. PROTOPLAST FUSION
When fusion of gametes fails, protoplast fusion of somatic cells can be attempted.
9. EMBRYO RESCUE
Hybrid zygotes formed by wide crosses may fail to grow in a number of cases. The
zygotes are taken out and grown in in vitro medium to overcome this problem.

14. Limitations of Distant hybridization
1. Incompatible crosses
2. F1 sterility
3. Problems in creating new species
4. Lack of homoeology between chromosome of the parental species
5. Undesirable linkages
6. Problems in the transfer of recessive oligogenes and quantitative traits
7. Lack of flowering in F1
8. Problems in using improved varieties in distant hybridization
9. Dormancy

15. MAIZE = Zea mays (2n=20)

16. Wild relatives
• Teosintes
• Tripsacum
 Biotic stress-Tolerance to chlorotic dwarf virus, downy
mildew, Fusarium, Striga hermonthica, rootworms.
 Abiotic stress-Drought and flooding
 Quantitative traits

17. WILD ZEA SPECIES
Seven genera
• Coix (2n = 10 or 20)
• Chionachne (2n = 20)
• Sclerachne (2n = 20)
• Trilobachne (2n = 20)
• Polytoca (2n = 20) (Aditya and Jitendra, 2014)
Teosintes
 Zea diploperennis (2n= 20)
 Zea perennis (2n= 40)
 Zea luxurians, Zea mays spp. Parviglumis
 Zea mays spp. huehuetenangensis (Reeves and Mangelsdorf, 1942; Hitchcock,
1951; Iltis et al., 1979; Iltis and Doebley, 1980; Doebley, 1990b; Watson and
Dallwitz, 1992; Aditya and Jitendra, 2014).

18. Tripsacum genus
• Tripsacum dactyloides (L., 2n = 72)
• T. laxum Scrib and Merr (2n = 36)
Other species
• T. andersonii (2n = 64)
• T. latifolium (2n = 36)
• T. lanceolatum (2n = 72)
• T. floridanum (2n = 36)
• T. manisuroides (2n = 72) (De Wet and Harlan, 1972; De Wet et al.,1972; De
Wet et al., 1983; Talbert et al., 1990; Watson and Dallwitz, 1992; Aditya and
Jitendra, 2014)

19. Disease resistance
• Findley et al. (1982) introgressed resistance against maize
chlorotic dwarf virus (MCDV)
Z. diploperennis X Z. mays
2n= 20 2n= 20
F1 X Backcross
MCDV

20. Downy mildew
 Z. mays ssp. mexicana, Z. diploperennis, and Z. perennis into
maize were carried out by Ramirez (1997) using sexual
hybridization
Fusarium wilt
 Reported in F1 and F2 generations of crosses between maize
and Z. mays ssp. mexicana (Pásztor and Borsos, 1990).
Other disease
 Bergquist (1979) T. dactyloides crossing with maize where
sexual mating is difficult, against Colletotrichum graminicola,
Helminthosporium turcicum, H. maydis, Erwinia stewartii and
Puccinia sorghi by backcrossing into various maize genotypes.

21.  Bergquist (1981) successfully transferred a dominant gene RpTd
conferring resistance against rust pathogen of corn Puccinia
sorghi, from T. dactyloides.
 T. floridanum was used to introgress resistance gene Ht into the
genetic background of maize (Hooker and Perkins, 198
 Zhou et al. (1997) conducted the distant hybridization involving
maize × teosinte (Z. diploperennis L.) in order to introduce novel
genetic variability. They reported fourteen inbred lines resistant
to diseases, insects and environmental stress after eighth-
generation selfing and selection. The best crossing of these 14
lines with normal testers produced 1,000 hybrids which showed
strong heterosis).

22.  Wei et al., (2003)Alloplasmic inbred lines derived from maize
× Z. diploperennis interspecific hybrids were reported to
exhibit resistance against H. turcium and H. maydis.

23. Parasitic weed resistance
• Rich and Ejeta (2008) -Tripsacum dactyloides resistance to the
„witch weeds (Striga species)‟
• Kim et al.,(1999) -Teosintes (Z. diploperennis) and T. dactyloides
higher levels of resistance
• Lane et al.(1997))nternational Institute of Tropical Agriculture
(IITA) developed a Striga hermonthica-resistant inbred, ZD05
• This inbred has in its pedigree a Z. diploperennis accession as well as
tropical maize germplasm (Menkir et al., 2006; Amusan et al., 2008)
• The resistant ZD05 and the susceptible 5057 differed in root
morphology

25. Insect resistance
• Ramirez (1997) Z. mays ssp. mexicana, Z. mays ssp.
diploperennis and Z. mays ssp. perennis, have resistance to to
the Asiatic corn borer.
• Pásztor et al. (1990) maize × Z. mays ssp. mexicana hybrids
resistance to the corn borer (Ostrinia nubilalis)

26. ABIOTIC STRESS RESISTANCE
Drought resistance
 Comis et al.(1997) Tripsacum is a ability to withstand drough. The studies of
aerenchyma tissue
 And Bradford et al.(1985)Physiological evidence suggests that superior drought
tolerance in Tripsacum is based on high photosynthesis and WUE in leaf gas
exchange
Tolerance to flooding
 Bird et al. (2000) Teosintes, viz. Z. nicaraguensis
 Mano et al. (2005) Z. luxurians and Z. mays ssp. huehuetenangensis have been
observed to exhibit a higher capacity for adventitious root formation than
some maize inbreds.
 Z. mays ssp. huehuetenangensis seedlings were observed to exhibit a high
adaptability to flooding by developing adventitious roots above the soil surface
the adventitious roots of this teosinte can obtain oxygen, and this characteristic
may play an important role in its adaptation to flooding conditions.
 Ray et al. (1999) Z. nicaraguensis and Z. luxurians were reported to develop
well- formed aerenchyma in adult plants.

27. Yield and yield related traits
 Karn et al.(2017) Near isogenic lines (NILs)
 Zea mays ssp. parviglumis X inbred B73
 4 generations to creating a 916 inbred lines
 They identified a total of eight QTL across the three traits
 Two starch QTLs that explained 18% of the variation
 Three protein QTLs that explained 23% of the variation,
 six oil QTLs which explained 45% of variation
 The chromosome 1 QTL was significant for both protein and oil
 The chromosome 3 QTL was significant for all three traits.
 In addition, a total of 9 starch, 12 protein, and 25 oil teosinte significant alleles were
identified
 All the QTLs had a range of strong additive allelic effects, with the largest allelic effects for
starch, protein, and oil QTLs being -2.56, 2.21 and 0.61% dry matter, respectively, and
displayed both positive and negative additive allelic effects depending upon the trait.

28. VIGNA SPECIES

29. • Gosal and Bajaj (1983) successfully obtained interspecific
hybrids between black gram (vigna mungo) and green gram
(vigna radiata) by rescuing the 11-17-day- old embryos on MS
medium supplemented with 1 mg/L IAA, 0.2 mg/L kinetin,
500 mg/L casein hydrolysate and 70 ml/l coconut water and
resulted that F1 plants were partially fertile and intermediate
between the two parents, and in F2 generation, different
combinations of desirable characters appeared and setting
percentage was also improved.

30. Character Species References
Resistance to bruchid V. riukinensis
V. radiata var. sublobata
Tomooka et al., (1992 )
Miyagi et al., (2004)
V. umbellata Tomooka et al., (2000)
V. nepalensis Somta et al., (2008)
Resistance to cowpea
storage weevil
V. vexillata
V. reticulata
V. oblongifolia
V. luteola
Resistance to powdery
mildew V. stipulaceae
Tomooka et al., (2006)
High methionine content
High photosynthetic
efficiency and drought
tolerance
V. radiata var. sublobata
V. radiata var. sublobata
Babu et al.,(1988)
Ignacimuthu (1987)

31. Drought tolerance V. aconitifolia Jain and Mehra (1980)
Heat tolerance V. aconitifolia Tomooka et al., (2001)
Insect resistance V. unguiculata ssp.
dekindtiana var.
pubescens
Ehlers and Hall (1997)
YMV resistance V. radiata var. sublobata Singh and Ahuja (1977)
Resistance to pod bug V. unguiculata ssp.
dekindtiana
Koona et al., (2002)
Resistance to cowpea
Resistance to yellow
mosaic virus nsects
pests
V. vexillata
V. radiata var. sublobata
V. umbellata
Birch et al., (1986)
Pal et al., (2000)
Pandiyan et al., (2008)
YMV resistance V. radiata var. sublobata Singh and Ahuja (1977)

32. VBN) (Gg) 2 (susceptible ) X MYMV resistant)
female Male
 A total of 83 seeds were harvested from 10 F1 plants.
 F2 seeds only 12 plants reached maturity
 When considering growth habit of the plants in this cross, the female parent (V. radiata) was erect
while male parent (V. stipulacea) was trailing. But the F1 hybrids were erect while in F2 generation,
out 12 plants four were trailing in nature
 The leaf lobing pattern of female parent (V. radiata) was deep whereas male parent (V. stipulacea)
had shallow lobing pattern. The F1 plants expressed leaf lobing pattern of both the parents
 Seed colour, female parent (V. radiata) was shiny green but male parent (V. stipulacea) expressed
dull black whereas the hybrid seeds were dull green in nature
 In the F2 generation, individual segregants were weak and produced less number of pods
Vigna stipulacea

33. Gene Pools of Cajanus

34. Pre-breeding using wild Cajanusspecies

35. Pre-breeding using wild
Cajanusspecies and
pigeonpea cultivars for
broadening the genetic
base for pigeonpea
improvement

37. Pod formation in the cross (Cajanus acutifolius × C. cajan) Immature seeds seen in BC1F1 hybrid pods (C. acutifolius × C.
cajan) × C.cajan

38. Sharma et al(2016)

39. Female Parents
Cajanus platycarpus
Male parents
Cajanus cajan
Tetraploid progeny

40. Cajanus platycarpus Cajanus cajan F1 (tetraploid)
F2 (tetraploid) F3 (tetraploid)
In-ovulo embryo culture Hybrid embryo
culture
Multiple shoots from
hybrid embryo.
In vitro rooting of
hybrid shoots

41. F3 (tetraploid) podsFemale Male F2
F1BC2 (diploid) pods Cajanus cajan Cajanus platycarpus
F1
F2 F3 Diploid F1BC2 seeds

42. Comparison of F1 hybrids (B, C, D, E and F plants) with the female parent Cajanus cajan (A) and male parent
Cajanus lanceolatus (G

44. COTTON

47.  12 Gossypium hirsutum genotypes (tetraploid 2n=4=52)
 2 Jassid resistant wild (diploid 2n=2x=26) species
 Gossypium raimondii
 G. armourianum

49. G. hirsutum (MCU 9) G. armourianum
F1
x
Doubled triploid

50. Backcross derivative C1 (MCU 9X G. armourianum)XMCU
Backcross reciprocal derivative

51. G. hirsutum (Surabhi) G. raimondii
F1

52. Doubled triploid
Comparative features of F1 and
their parents
Backcross derivative
Second backcross derivative

53. CHICKPEA

54. Details of parents along with their characteristics
Wide Hybridization in Chickpea for Creating Variability and Increasing Yield
via More Number of Primary Branches per Plant
Neelu Mishra et al.,(2016)

55. Detail of 8 crosses made for experiment

56. Cicer reticulatum (EC556270)

57. Mean values for hybrids

58. Desirable type of plant obtained by wide hybridization

60. Life cycle of broom rape