Niu Yingze
Dept,of Plant Breeding and Seed Engineering
1.The Concept and Types of Plant Polyploidy
(1)Plant Ploidy,
§ 1 Polyploidy in Plants
Ploidy Chrom’s Genome
Haploid 1n 1x,2x,3x …
monoploid 1n 1x
Diploid 2n 2x,4x,6x …
Polyploid > 3x >3x
Types of Polyploids in Plants
Autopolyploids – Triploid 3x,Tetraploid 4x,Pentaploid
e.g,Potato (2x,3x,4x,5x x=12);
Sweet potato (2n=6x,90)
Allopolyploid – Tetraploid 4x,Hexaploid 6x,Octaploid 8x,…
e.g,Watermelon (3x,seedless)
Autoallopolyploid – Pentaploid 5x,Hexaploid 6x,…
e.g,Pheum pratense 梯牧草 (6x=42,AAAABB)
Monosomic (2n-1) Nullisomic (2n-2)
Trisomic (2n +1) Tetrasomic (2n+2)
2,Origin and Evolution of Polyploids
? Popularity of Polyploidy in Plant Kindom p,172
> 50% in angisperm plants 被子植物
ab,70% in grasses (Tab,10-1,2 p,172-173)
? Natural Origination
Egg (2n) + Pollen (n) Triploid Tetraploid
(unreduced) (reduced) (selfing,backcrossing)
? The evolution of Common Wheat (Triticum aestivum L.)
Evolution of Brassica Crops( The U’s Triangle)
3,General characteristics of polyploid plants
a) Giantness b) Low fertility c) More resistant to stresses
4,Application of Polyploidy in Plant Breeding
? 3x,4x grape Big fruits,seedless
? 4x Tomato High Vc content
? 3x watermelon Big fruit,seedless
? 3x azalea 杜鹃花 Big flower,long period of flowering
§ 2 Polyploid Breeding 多倍体育种
1,Selection of Materials
? Agronomically superior
? Smaller Chromosome number
? Capable of asexual fruit setting
? Treat more varieties
2,Induction of Polyploids
(1) Physical Induction (temperature,injury,irradiation)
(2) Physical Induction (秋水仙素)
(3) Sexual Cross ( e.g 2x x 4x = 3x)
(4) Endosperm Culture
(5) Clonal Variation of Somatic Cells
3,Identification of Polyploidy
(1) Direct Identification
Cytological observation,root tip/stem tip
(2) Indirect Identification
Giantness in the polyploid plants
- leaf
- flower
- fruit,seed
- chloroplast
- storma
- pollens
§ 3 Haploid and its Application to Plant
1,Types of Haploids
? Monohaploid (1x) 一元单倍体,一倍体
? Polyhaploid (>= 2x) 多原多倍体
Dihaploid 二元多倍体,双单倍体
Trihaploid 三元多倍体
… …
( 2) Characteristics of Haploids
a) Fertility
Fully male and female sterile
b) Heredity
Expression of recessive genes
Homozygous and stable after chrom’ doubling
(Doubled haploid,DH)
2,Induction of Haploids
( 1) Tissue and Cell culture
a) Anther culture
b) Pollen culture (Microspore culture)
c) Ovary or nucellus culture
A,Biological Methods
a) Pollination with distantly related species
b) Delayed pollination
c) Semigamy 半配生殖
Egg and pollen nucleus do not fuse to produce a zygote
d) Twin seedling,双生苗 ( Natural parthenogenesis 单性
生殖 n/n,n/2n,n/3n; where n is a parthenogenic seed
e) Chromosome degradation
B,Physical Methods
C,Chemical Methods
(2) In vivo Induction
3,Identification and Doubling of Haploid
(1) Identification
a) Morphology
b) Physiological and Biochemical characteristics
c) Genetic markers
d) Cytology
(2) Doubling
a) Natural doubling (relatively low)
b) artificial doubling 50ppm colchicine 秋水仙素
4,Application of Haploid in Plant Breeding
1) Shorten the Segregation period of Hybrids - Quick
homozygosis,shorter breeding cycles
2) Enhance the selection efficiency
3) Selection of recessive mutations
Class Test 3 Translate the following terms
1) Homogeneous and homozygous Cultivars
2) Homogeneous and heterozygous Cultivars
3) Heterogeneous and homozygous Cultivars
4) Heterogeneous and heterozygous Cultivars
5) Pure line cultivars
6) Hybrid cultivars
7) Population cultivars
8) Clonal cultivars
9) Conventional Cultivars
10) Synthetic Cultivars
11) Multi-line cultivars
(Think them over after class)
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