Chapter 2
Plant Germplasm
Niu Yingze
Dept,of Plant Breeding and Seed Engineering
§ 1 Importance of Germplasm Resources
1.The Concept of Germplasm
Resources 种质资源的概念
Genetic Resources
Gene Resources
Varietal Resources
Gene Bank
It refers to all the plant
materials used for plant
2.The Importance of Plant germplasm
? Germplasm Resources are a physical foundation for Plant
breeding,Polymorphism of germplasm assures successful
? In past plant breeding,all breakthroughs in Plant breeding
come from discoveries of extraordinary source of plant
e.g,Dwarf genes in wheat and rice
cms genes in rice,sorghum,rapeseed
O2 gene in maize
,00” genes in rapeseed
3.The Imperativeness of Germplasm Protection
保护 种质资源的紧迫性
It is imperative(紧迫) to protect the Plant Germplasm
Resources from extinction(灭绝),
, Development of industries,cities and roads
, Extension and popularization of new improved crop
, Environmental Pollutions (atmosphere and
, Man’s destroying
§ 2 Theories on Centers of Crop
1,The theory of Vovilov(1920)
1) Outline of the theory p.23-24
? Origin center,Big diversity; Dominant characters;
Wild types
Primary origin center; second origin center
2) The 8 centers of crop origination (p.24)
2,The theory of Harlan
Center-non-center theory (Harlan,1971)
Three centers of origin,Near East; N.China; C,America
Three non-centers,Africa; SE Asia; S,America
Harlan preferred regions of origin to centers of origin,
3,The theory of Zeven、茹考夫斯基
Proposed 12 megagene centers ( p.25)
4,Implication of Origin Centers in Plant Breeding
The theories of origin centers help in the choice of areas for
germplasm exploration and collection,Origin centers are
always the centers of diversity,
The centers of origin should also attract the attention of
biologists to save the rare germplasm which may otherwise
become extinct under fast changing natural conditions and
intensive agriculture,
1,Source Based Classification of Plant Germplasm
1) Local germplasm Strong local adaptation;
Comprehensively superior characteristics
2) Exotic germplasm Special characters and types absent in
local germplasm
3) Wild germplasm With special characters absent in
cultivated plants and strong stress,disease,and pest
resistance or tolerance,
4) Artificial germplasm Abundant breeding lines with certain
useful agronomic and economic characteristics
§ 3 Classification of Germplasm and Characteristics
2,Utility Based Classification of Germplasm
1) Primary Gene Pool (GP-1) Easy crossing and
normal seed set
2) Secondary Gene Pool (GP-2) Some barriers of
Crossability; abnormal chromosome pairing in F1
3) Tertiary Gene Pool (GP-3) Difficult Crossing,
progeny sterile and abnormal,special techniques as
embryo culture required
4) Fourth Gene Pool (GP-4) The entire world of
living organisms,genes of which can be transferred
by technology of genetic engineering
§ 4 Exploration and Collection of
1,Where to collect?
Centers of origin / Centers of diversity
2,How to collect?
Survey and collect; Mail request; exchange; purchase,etc,
3,How much to collect?
a) pure line /variety small quantity
b) heterozygous population (varieties) bigger quantity
c) asexually propagated crops small quantity
4,Data Processing and Documentation 整理建档
1,Planting conservation 种植保存
Once in every 2-3yrs
2,Storage conservation 贮藏保存
Seed storage term,
short 2-5 years
medium 10-20 years
long >20 years
Storage conditions (factors)
Water content; temperature; humidity; oxygen; light
§ 5 Conservation of Plant Germplasm
3,In vitro preservation 离体保存
Tissue/cell culture under low temperatures,cold
preservation(0 ~ -10 ℃ ) ; ultra low temperature
preservation (-196,liquid nitrogen)
4,Gene library conservation 基因文库保存
Isolation of large DNA molecules— enzyme restriction ---
DNA segments---conduction into E,coli ---amplification of
single copies---gene library,
5,Utilization and Conservation 利用保存
Hybridization to Conserve valuable genes in Breeding lines
§6 Study and Utilization of Plant Germplasm
1,Identification,Evaluation,and Study of Germplasm
Identification in multiple environments
Genetic studies and analyses for valuable characters
Documentation and Database establishment
Utilization in plant breeding,even directly in
3,Innovation of germplasm
Creation of new germplasm
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