The progeny rows showing variation may be selected for desirable mutants which are harvested individually;
5th year M4
Evaluate the bulked or individual lines in preliminary trials to select the best lines for further evaluation;
3.1 The type of physical mutagens：
physical mutagens
Ionizing（电离） radiations
electromagnetic radiations (low energy)
Particles
electromagnetic (high energy)
Lethal dosage（致死剂量）
LD50：when seeds are used ,the dose that is
sufficient（足够） to inhibit（保证）the germination（萌芽） of 50% seeds
Critical （临界）dose： the dose that is sufficient to inhibit the germination of 40% seeds
Hybrid materials .
3.2.2 methods：
(1)outer radiation ：X-rays, γ-rays, neutron operator.
(2) inner radiation：32P, 35S, 131I, 14C, 3H, Na2H32PO4. by injection, or dipping in mutagens（诱变剂）
laser
UV
radiations
（2000-3900Å）
Non electric electric
Particles
particles γ-rays X-rays
(0.1-1Å) （100-1000Å）
neutron proton
β -radiation
质子 proton 中子 neutron
α-radiation
Grow progeny rows of each plant; Identify rows showing mutations and select desirable mutant plants; Harvest the seed of each selected plant separately 选择突变体的关键世 代
Chapter 10 Mutation Breeding
Later 20 century：laser breeding and space breeding .
啊，又一颗卫星飞上太空， 人类的生活进入新的日程—— 卫星载着地球的种子， 让稻麦蔬菜去享受新生……
多么奇妙！遨游数日以后， 种子再回来便有了特异功能！ 经过选育的青辣椒， 一个就会长到半斤重！
Mutagen action
DNA
replication
TTATGCATC
TTATGCATC
A A T GA C G T A G
Original DNA
A A TG C G T A G
Illegitimate pairing
TTACGCATC A ATG CG T A G
Mutated DNA
b. Mutagenic induced chromosome deletion
3.2 The methods of physical mutagents
3.2.1 materials：
seeds, plants, pollen（花粉）, egg cells ovary, gametes（配子）, zygote（受精 卵）, embryo、asexual reproductive organs.
Pedigree methodYear 1st yeaFra bibliotek 2nd year
3rd year
Generat ion
M0 M1
M2
Operation
Treat the seed (500 or more) with appropriate mutagen
Grow the seeds as space planted in isolation; Some plants may be chimeras; The dominant mutations may be observed; Harvest about 20 seeds from each M1 plant or spike individually 通常不进行选择
(3)Eating method（施入法） ：by applying mutagenic solution into plant growth medium which is absorbed throng roots.
The seedling irradiated by fast neutron in different dose
3 physical mutagens and its methods
4. Mode of Action of Mutagens 5 Chemical mutagens and its methods
6. Screening the populations to select mutants desirable
The rate of spontaneous mutations is very low, usually one out of million for an individual gene. The rate of induced mutations is much higher than spontaneous mutations
(from 100 times to 1000 times)
Change some traits coded by one gene effectively；
Can be used simply，fasten the stable rate，shorten the time of breeding；
牧草与草坪草育种学——绪论
4.3 The elements affecting the effects of the mutation ✓Solution density浓度 ✓Time ✓temperature
5. Mode of Action of Mutagens
a. Mutagenic induced change in the base sequence of DNA
uniform mutation after the identification
of desirable traits pure line after being
induced, shorten breeding time greatly.
3. physical mutagens and its methods
Mutation breeding scheme for seed
propagated self-pollinated crops
Pedigree method
Year
Genera Operation
tion
4th year M3
Grow individual plant progenies;
Select the mutant and uniform lines which may be bulked if homogeneous;
propagated(繁殖) by seed，can be stable in F3，and the new variety can be bred in 3~6 year;
propagated by vegetable organ（营养 体），can be propagated to produce
哈！最大的青辣椒！ 一个就能炒一盘美味佳肴， 而且它那维生素C的含量， 会有百分之十五以上的提高……
哈！小麦的种子也因此而变异， 新的麦苗可早熟又抗病抗倒。 科学真好！太空育种真妙！ 这其中的奥秘谁能知道？
1.Histroy
2. The function and position of induced mutation
4. Chemical mutagens and its methods
4.1 The type of chemical mutagens：
(1)烷化剂类：以活跃的烷基取代其它分子的氢原子，从而导致遗 传密码改变。常用的有甲基磺酸乙酯(EMS)、硫酸二乙酯(DES)、 乙烯亚胺(EI)、N-亚硝基-N-乙基脲烷(NEU)和亚硝基乙基脲 (NEH)等。这也是目前应用广、效率高的一类化学诱变剂。
(2)核酸碱基类似物：在化学结构上与核酸碱基相似，不妨碍复制， 但因碱基配对差错而引起突变。如：5-溴尿嘧啶(5-BU)、咖啡 碱、马来酰肼等与胸腺嘧啶极为近似，可以“冒名顶替”引起复 制差错，而造成基因突变。
(3)其它 如甲醛、抗生素（链霉黑素）、亚硝酸、生物碱（秋水 仙碱、喜树碱）等。
4.2 methods： (1)Dripping滴液 (2) Injection (3)Painting涂沫法 (4)Steaming熏蒸法 (5)Soaking浸渍法
1.Histroy
（1）physical induced mutation：
1904: De.Vries had a foresight to suggest the use of radiation to induce mutation. 1908: Gager reported the result of induced mutation. 1927：Muller HJ. found a large number of mutant in fruit fly by X-rays.