CHAPTER 9 DISTANT CROSS BREEDING 远缘杂交育种 BY Niu Yingze (牛应泽) Dept. of Plant Breeding and Seed Engineering The Concept of Distant Cross p. 159 Distant Cross : Between Species Distant cross – Distant hybridization – Wide cross Sub-distant Cross: Between Subspecies Near Cross: Between Varieties §1 Concept and Roles of Distant Cross 远缘杂交的过概念和作用 2. Roles of Distant Cross Creation of new crop types: Triticale Creation of new male sterile types: Backcrossing Transfer of pest and stress resistance: Late blast resistance in wild potato Improvement of crop quality: High strength Fiber breeding in cotton Vc content in Tomato (5) Induction of Haploidy Barley H. bulbosum induces haploids in barley and wheat (6) Use for studies of evolution of Crops 2n wheat – 4n wheat – 6n wheat B. campestris x B. oleracea --- B. napis (7) Use for Heterosis In cotton: 陆地棉× 海岛棉——杂种F1 In vegetables: Use of vegetative heterosis Nucleus – cytoplasmic Hybrids/Fixed heterosis §2 Difficulties and Solutions in Distant Cross Breeding 远缘杂交的困难与克服方法 Three big difficulties: Cross patibility Hybrid death and sterility Wide segregation of offspring 1. Cross patibility in Distant Cross Cross patibility (noncrossability) Pollens not germinate pollen tubes not rate into the stigma Pollen tubes not reach the embryo sac Degradation of pollen nucleus in the sac … (2) The Couses Structures of an: Stigma lengths Physiological disharmony: Enzymes; PH; Osmosis ic disharmony: Chromosome number; Chrom’ Lengths; Crossability genes: . kr1, kr2 in wheat “China spring” 2. Solutions to Cross patiblity Chromosome doubling of the parents bination of the parents Internediator plant Special methods for pollination: Mixed pollens Repeated pollination Advanced or delayed pollination Irradiation treatment of pollens 2. Solutions to Death and Sterility of Distant Hybrids 远缘杂种夭亡和不育的克服方法 Death and Sterility in the Distant Hybrids Death and Sterility of Hybrids Death of young embryo (
