CHAPTER 9
DISTANT CROSS BREEDING
远缘杂交育种
BY
Niu Yingze
（牛应泽）
Dept,of Plant Breeding and Seed Engineering
1,The Concept of Distant Cross p,159
? Distant Cross, Between Species
Distant cross – Distant hybridization – Wide cross
? Sub-distant Cross,Between Subspecies
? Near Cross,Between Varieties
§ 1 Concept and Roles of Distant Cross
远缘杂交的过概念和作用
2,Roles of Distant Cross
(1) Creation of new crop types,e.g Triticale
(2) Creation of new male sterile types,Backcrossing
(3) Transfer of pest and stress resistance,Late blast
resistance in wild potato
(4) Improvement of crop quality,
High strength Fiber breeding in cotton
Vc content in Tomato
(5) Induction of Haploidy
e.g Barley H,bulbosum induces haploids in barley
and wheat
(6) Use for studies of evolution of Crops
e.g 2n wheat – 4n wheat – 6n wheat
B,campestris x B,oleracea --- B,napis
(7) Use for Heterosis
In cotton,陆地棉 × 海岛棉 ——杂种 F1
In vegetables,Use of vegetative heterosis
Nucleus – cytoplasmic Hybrids/Fixed heterosis
§ 2 Difficulties and Solutions in Distant
Cross Breeding
远缘杂交的困难与克服方法
Three big difficulties,
? Cross incompatibility
? Hybrid death and sterility
? Wide segregation of offspring
1,Cross Incompatibility in Distant Cross
(1) Cross incompatibility (noncrossability)
Pollens not germinate
pollen tubes not penetrate into the stigma
Pollen tubes not reach the embryo sac
Degradation of pollen nucleus in the sac …
(2) The Couses
Structures of floral organ,Stigma lengths
Physiological disharmony,Enzymes; PH; Osmosis
Genetic disharmony,Chromosome number; Chrom’
Lengths; Crossability genes,
e.g,kr1,kr2 in wheat ―China spring‖
2,Solutions to Cross incompatiblity
(1) Chromosome doubling of the parents
(2) Appropriate combination of the parents
(3) Internediator plant
(4) Special methods for pollination,
Mixed pollens
Repeated pollination
Advanced or delayed pollination
Irradiation treatment of pollens
2,Solutions to Death and Sterility of
Distant Hybrids
远缘杂种夭亡和不育的克服方法
1,Death and Sterility in the Distant Hybrids
(1) Death and Sterility of Hybrids
? Death of young embryo (abnormal zygote
development,imperfect embryos; imperfect
seed,…)
? Sterility of adult hybrid (male,female sterile)
(2) Causes
? Imbalance in interaction of nucleus and cytoplasm
? Imbalance in chromosomes (Chrom’ number)
? Imbalance in genes (Alien DNA degradation)
2,Solutions to the death and Sterility of
Distant Hybrids
(1) Embryo Culture
(2) Chromosome Doubling
(3) Backcross,to the cultivated parent
(4) Better careful cultivation
(5) Elongation of growing period
(6) Grafting
§ 4 Segregation and Selection of the Distant
hybrids 远缘杂种的分离与选择
1,The characteristics of segregation and
inheritance of the distant hybrids
(1) Large segregation
(2) Irregular segregation
(3) Long term segregation/slow stabilization
2,Control of the segregation of distant hybrids
(1) Backcrossing
(2) Chromosome doubling of F1
(3) Induction of haploids （单倍体）
(4) Induction of chromosome translocation
3,Selection of the offspring of distant hybrids
(1) Large population for selection in the early generations
(2) Less strict selection criteria in the early generations
(3) Flexible selection methods for the distant hybrids
Till Next Chapter
DISTANT CROSS BREEDING
远缘杂交育种
BY
Niu Yingze
（牛应泽）
Dept,of Plant Breeding and Seed Engineering
1,The Concept of Distant Cross p,159
? Distant Cross, Between Species
Distant cross – Distant hybridization – Wide cross
? Sub-distant Cross,Between Subspecies
? Near Cross,Between Varieties
§ 1 Concept and Roles of Distant Cross
远缘杂交的过概念和作用
2,Roles of Distant Cross
(1) Creation of new crop types,e.g Triticale
(2) Creation of new male sterile types,Backcrossing
(3) Transfer of pest and stress resistance,Late blast
resistance in wild potato
(4) Improvement of crop quality,
High strength Fiber breeding in cotton
Vc content in Tomato
(5) Induction of Haploidy
e.g Barley H,bulbosum induces haploids in barley
and wheat
(6) Use for studies of evolution of Crops
e.g 2n wheat – 4n wheat – 6n wheat
B,campestris x B,oleracea --- B,napis
(7) Use for Heterosis
In cotton,陆地棉 × 海岛棉 ——杂种 F1
In vegetables,Use of vegetative heterosis
Nucleus – cytoplasmic Hybrids/Fixed heterosis
§ 2 Difficulties and Solutions in Distant
Cross Breeding
远缘杂交的困难与克服方法
Three big difficulties,
? Cross incompatibility
? Hybrid death and sterility
? Wide segregation of offspring
1,Cross Incompatibility in Distant Cross
(1) Cross incompatibility (noncrossability)
Pollens not germinate
pollen tubes not penetrate into the stigma
Pollen tubes not reach the embryo sac
Degradation of pollen nucleus in the sac …
(2) The Couses
Structures of floral organ,Stigma lengths
Physiological disharmony,Enzymes; PH; Osmosis
Genetic disharmony,Chromosome number; Chrom’
Lengths; Crossability genes,
e.g,kr1,kr2 in wheat ―China spring‖
2,Solutions to Cross incompatiblity
(1) Chromosome doubling of the parents
(2) Appropriate combination of the parents
(3) Internediator plant
(4) Special methods for pollination,
Mixed pollens
Repeated pollination
Advanced or delayed pollination
Irradiation treatment of pollens
2,Solutions to Death and Sterility of
Distant Hybrids
远缘杂种夭亡和不育的克服方法
1,Death and Sterility in the Distant Hybrids
(1) Death and Sterility of Hybrids
? Death of young embryo (abnormal zygote
development,imperfect embryos; imperfect
seed,…)
? Sterility of adult hybrid (male,female sterile)
(2) Causes
? Imbalance in interaction of nucleus and cytoplasm
? Imbalance in chromosomes (Chrom’ number)
? Imbalance in genes (Alien DNA degradation)
2,Solutions to the death and Sterility of
Distant Hybrids
(1) Embryo Culture
(2) Chromosome Doubling
(3) Backcross,to the cultivated parent
(4) Better careful cultivation
(5) Elongation of growing period
(6) Grafting
§ 4 Segregation and Selection of the Distant
hybrids 远缘杂种的分离与选择
1,The characteristics of segregation and
inheritance of the distant hybrids
(1) Large segregation
(2) Irregular segregation
(3) Long term segregation/slow stabilization
2,Control of the segregation of distant hybrids
(1) Backcrossing
(2) Chromosome doubling of F1
(3) Induction of haploids （单倍体）
(4) Induction of chromosome translocation
3,Selection of the offspring of distant hybrids
(1) Large population for selection in the early generations
(2) Less strict selection criteria in the early generations
(3) Flexible selection methods for the distant hybrids
Till Next Chapter
