普通小麦(Triticum aestivum)和毛穗赖草(Leymus paboanus)的杂交,杂种细胞无性系的建立及植株再生

Hybridization of Triticum aestivum with Leymus paboanus the Establishment of Somatic Callus Clones of the Hybrid Embryos and Plant Regeneration

以3个普通小麦品种富可(Fuhuko)、中国春(Chinese Spring)及小偃759和毛穗赖草杂交,发现三个品种都可与毛穗赖草杂交,其中Fuhuko×L.paboanus平均结实率高达17.6％,杂种只有发育不全的幼胚而无胚乳。对杂种幼胚在N_6+1—2mg/11BA+0.5mgGA_3或MS(其中NH_4NO_3含量降低一半)附加1mg/1IBA的培养基上进行保姆培养,部分幼胚发育成完整的小植株,大部分幼胚死亡,并且在MS(1/2NH_4NO_3)培养基上,两个胚(Fuhuko×L.psboanus)形成质量很差的小愈伤组织,对其进行改良培养,建立了两个杂种胚性无性细胞系(一个生长很快,另一个相对较慢)。杂种愈伤组织在附加1mg/1IBA的MS或N_6培养基以及附加(0.5mg NAA+0.5mgKT)/1的MS(1/2NH_4NO_3)分化培养基上均可高频率产生再生植株。同时发现:1.将MS培养基中硝酸铵的含量降低一半,可显著提高植株再生频率;2.降低分化培养基中生长素(如IBA,NAA)的含量,加入少量的细胞激动素(如0.5 mg/1KT)可促使大量胚状体萌发,产生正常植株,使绿苗中90.0％以上的植株来自胚状体发生途径。细胞学观察表明:幼胚直接成苗的杂种植株体细胞染色体数很稳定,2n=63+1B,和预期结果相符;而杂种愈伤组组再生植株染色体数极不稳定,不同株间染色体数不同,即使同一根尖中不同的细胞染色体数也有很大差异。

Three bread wheat varieties, Fuhuko, Chinese Spring and Xiaoyan 759, were,crossed with L. paboanus. The results indicated that all of the 3 wheat varieties werecrossible with L. paboanus, with Fuhuko/L. paboanus having the highest seed set-ting percentage, 17.6%. The seed, however, had only underdeveloped embryos andno endospermum. The immature hybrid embryos were put under nursing culture onN6 medium+ 1mg /l IBA+0.5 mg /l GA, or MS mediurn with the amount ofNH_4NO_3 reduced to one half of the original. Most of the immature embryos died,but some of them developed into plantlets directly. And 2 immature embryos of thecross Fuhuko/L. paboanus on the second medium produced poorly developed calli.These were than subcultured on modified media, and finally, 2 different somaticembryogenic callus clones, one grew rapidly while the other relatively slowly wereestablished. The calli of both clones could produced high percentage of regeneratedplantlets on differentiation media MS or N_6 enriched with 1 mg /l IBA as well as onMS medium with 1/2 amount of NH_4NO_3 and 0.5 mg /l NAA and 0.5 mg /l KT.It was found that reducing the amount of NH_4NO_3 to one half of the original couldincrease significantly the percentage of plant regeneration, and reducing the amount ofauxin, such as IBA and NAA, and adding small amount of cytokinin, such as0.5 mg /l KT, could stimulate large amount of embryoids to germinate into normalplantlets. Thus, 90% of the green plantlets obtained came from regeneration ofembryoids. Results of cytological studies revealed that the chromosome number of plantlets re-generated directly from immature embryos was rather stable, where 2n= 63+1B, justas expected. But the chromosome number of those regenerated from calli were quiteunstable; various chromosome numbers were found in different plants, even in differ-ent cells of the same root tip. The reason of this phenomenon is not yet clear.