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异源四倍体（双二倍体）：
多倍体形成的两种主要途径： 1.远缘杂种和原种形成未减数配子
如，远缘杂交：卡贝钦科(1928)获得萝卜与甘蓝的属间杂种异源四倍体 2.原种或杂交种的合子加倍 幻灯片125
? Figure 18-11. A species triangle, showing how amphidiploidy has been important in the
production of new species of Brassica
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普通小麦的形成 幻灯片127
? ? ? ? ? ? ? ? ?
创造远缘杂交育种的中间亲本的实例
二粒小麦 × 伞形山羊草(抗叶锈病基因 R) 2n=AABB=14Ⅱ 2n=CuCu=7Ⅱ ↓
F1 ABCu=21Ⅰ ↓ 加倍 F1异源六倍体
2n=AABBCuCu=21Ⅱ，高抗叶锈病 ↓
? 用作中间亲本，再与普通小麦杂交和回交。 ? ↓
? 普通小麦品系（转入伞性山羊草抗叶锈病基因）
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Techniques for the production of the amphidiploid Triticale
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somatic hybridization
? make allopolyploid-like hybrids by fusing asexual cells. Cell suspensions are prepared and
stripped of their cell walls. The stripped cells are called protoplasts. The two protoplast
suspensions are then combined with polyethylene glycol, which enhances protoplast fusion. ? Theoretically, such a technique would allow us to combine widely differing parental species.
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