第一章 常规杂交育种解析

第一章常规杂交育种(Cross Breeding)

本章主要教学内容

杂交育种的原理和意义

杂交亲本的选择和选配

杂交方式和技术

杂交后代的选择和培育

第一节常规杂交育种的意义(Significant of Cross Breeding) 杂交育种的基本概念(Definitions)

杂交（Cross)：遗传类型不同的生物体相互交配或结合而产生杂种的过程。

有性杂交（Sexual cross)

无性杂交（Asexual cross)；

远缘杂交（Distant cross)

种内杂交（Cultivar cross).

常规杂交育种：按育种目标选择选配亲本，通过人工杂交的方法将亲本的优良性状集于杂交后代，再通过对杂交后代进行自交分离，选择出符合目标要求的，遗传性稳定一致的优良新品种。

常规杂交育种也称做重组育种、有性杂交育种、组合育种。

杂交育种的遗传学原理

❖基因的自由分离和重组规律

Mendel’s Principle of Segregation: Pairs of alleles segregate (separate) during gamete formation. Upon fertilization, the alleles are paired up again.

❖基因连锁互换规律

MORGAN’S LA WS：Genes occur in a linear order on chromosomes

Linked genes are on the same chromosome

Genes can be exchanged between chromosomes during meiosis ❖细胞质遗传规律(Cytoplasm genetic)

❖数量性状遗传（Quantitative trait genetic)

常规杂交育种的意义

1、实现基因重组，获得变异类型。

Realizing the recombination of genes and obtaining variation.

将分属于不同品种、控制不同性状的优良基因随机组合，形成各种不同的基因组合，再通过定向选择育成集双亲优良性状于一体的新品种。

2、打破不利基因的连锁关系。

Separating the linked disadvantageous genes with the advantageous genes on the same chromosome.

例：番茄抗病基因与黄化基因的连锁。

3、改善基因间的互作关系，产生新性状。

Changing the interaction of genes and producing the new trait.

4、综合双亲优良性状(产生超亲性状)。

Integrating the advantageous traits of the parents into the hybrid.

例：节间长、单节结荚多的甜豌豆品种与节间短的品种杂交后代，通过自交选育出节间短、单节结荚多的新品种。

第二节亲本的选择和选配(Selection and mating of parent)亲本的选择：指根据育种目标选用具有优良性状的品种类型作为杂交亲本。

亲本的选配：指从入选的亲本中选用哪些亲本杂交，怎样杂交。

一、亲本的选择原则

1. 广泛搜集符合育种目标原始材料，精选亲本

2.亲本应尽可能具有较多的优良性状

3.明确亲本的目标性状，分清目标性状的主次

4.重视选用地方品种

5. 亲本的一般配合力要高

二、亲本的选配的原则

1. 父母本性状互补

2. 选用不同类型或不同地理起源的亲本相配

3.以具有较多优良性状的亲本作母本

4.亲本之一的性状应符合育种目标(Why)

5. 用一般配合力要高的亲本配组

第三节杂交方式和技术

1、单交（single cross）

最简单的杂交方式，两个亲本的杂交方式，又称成对杂交。In case of single-cross hybrid, only two parents are taken.

2、多亲杂交（multiple cross）

参加杂交的亲本是3个或3个以上的杂交叫多亲杂交，又称复合杂交或复交。

根据亲本参加杂交的次序不同可分为添加杂交和合成杂交。

添加杂交多个亲本逐个参与的杂交。

[(A×B) ×C] ×D…

合成杂交:参加杂交的亲本先两两配成单交种，两个单交种再杂交。

(A×B) ×(C×D) …

特点：杂种群体的遗传基础丰富，亲本的核遗传组成均等

3. 回交（Backcross )

杂交一代及以后各世代与亲本之一再进行杂交。

Backcrossing is a form of recurrent hybridization by which a desirable allele for a character is substituted for an alternative, undesirable allele

Trait of interest should be simply inherited and easily phenotyped

Backcross Breeding Method

Generally this method is practiced for diseases, insects, or stress-resistance breeding programs of vegetable crops.

The backcross method is based on the principle of quick and efficient transfer of a gene by repeated backcross and then selection in F2 and subsequent segregating generations.

With continuous backcrossing with the recurrent parent, the characteristics of the recurrent parents are transferred in the backcross population and this population becomes homozygous, like the recurrent parent.

轮回亲本(recurrent parent)：在回交过程中多次参与杂交的亲本。

Recurrent parent is the parent to which the F 1 and subsequent generations are crossed.

Generally, the recurrent parent is a high-yielding, recommended variety but lacks one desirable trait.

This may be susceptibility to disease, insect, or stress conditions.

Recurrent parent should be a highly acceptable genotype (e.g. existing commercial cultivar or inbred line)

非轮回亲本( nonrecurrent /donor parent) ：在回交过程中只参加一次杂交的亲本，也叫做“供体”。

•Donor parent donates the desirable allele but does not enter into the backcross.

The nonrecurrent parent is mostly low yielding, but possesses a desired trait which the recurrent parent lacks. In most of the cases, wild species are used as nonrecurrent parents.

The best BC donor parent will possess the desired trait but will not be seriously deficient in other traits.

Backcross Breeding Method

Recovery of the recurrent parent genotype follows this pattern: