高温诱导胚囊染色体加倍选育杜仲三倍体

Chromosome Doubling of Embryo Sac Induced by High Temperature for Selective Breeding of Triploid in Eucommia ulmoides

杜仲是极具潜力的温带胶源树种,在环烯醚萜苷类等药效成分利用方面也具有重要价值。由于杜仲以单科单属单种存在,无法利用远缘杂交获得杂种优势,因此三倍体育种可能是大幅度提高叶片杜仲胶和药效成分等次生代谢产物含量的有效途径。本研究以杜仲为材料,开展施加高温处理诱导胚囊染色体加倍选育杜仲三倍体技术研究,结果表明,杜仲雌雄花芽发育具有一定的相关性,可以根据同栽培条件下相邻雄树散粉天数和雌花芽长度来估计杜仲胚囊发育进程。当相邻雄株散粉5~10 d时,对杜仲雌花芽分别施加45℃、48℃和51℃高温持续处理2 h、4 h和6 h诱导杜仲胚囊染色体加倍。其中,在相邻雄株散粉第6~10天时,对雌花芽施加48℃和51℃高温持续处理6 h各获得了1株三倍体;施加48℃高温持续处理4 h获得了4株三倍体。对施加高温处理同时固定的雌花芽进行组织切片观察表明,在相邻杜仲雄树散粉后第6~10天,杜仲胚囊发育处于3次有丝分裂时期,可同时见到单核胚囊、二核胚囊和四核胚囊,是施加高温处理诱导胚囊染色体加倍选育杜仲三倍体的有效时机。有关研究证明施加高温处理雌花芽诱导胚囊染色体加倍同样是一种获得杜仲三倍体的有效方法,对于杜仲遗传改良具有重要价值。

Eucommia ulmoides is a very potential tree species for gum utilization in temperate zone in China,and it is also of important value in the utilization of medicinal ingredients,such as iridoid glycosides.Offspring with high heterosis could not be obtained by interspecific crossing because Eucommia ulmoides is the single species in the Eucommia genus in the Eucommiaceae family.Therefore,triploid breeding may be an effective way to significantly improve the content of secondary metabolites in leaves,such as gutta-percha and medicinal components.In this paper,Eucommia ulmoides was selected as the material,and a study on technique of embryo sac chromosome doubling by high temperature to produce triploids of Eucommia ulmoides was conducted.The results showed that the development of female and male flower buds had a certain correlation,and the development period of embryo sac could be estimated based on the number of days after pollen release of neighboring male trees and the meanlength of female flower buds.When 5～10 days after pollen release of the neighboring male trees,the female buds were treated with 45℃,48℃ and 51℃ for 2 h,4 h and 6 h,respectively,to induce embryo sacs chromosome doubling.6～10 days after pollen released,one triploid was obtained under the treatments with 48℃ and 51℃ for 6 hours,respectively.Four triploids were acquired in the treatment with 48℃ for 4 hours.The cytological observation of the fixed female flower buds after high temperature treatment showed that the embryo sacs were in the third mitosis within 6～10 days after pollen released.The mononuclear,two and four nucleate embryo sacs could be observed at the same time.Therefore,6～10 days after pollen released was the effective period to induce embryo sac chromosome doubling by high temperature treatment in Eucommia ulmoides.Our studies proved that embryo sac chromosome doubling induced by high temperature exposure was an effective method to obtain triploid,which had important value for the genetic improvement in Eucommia ulmoides.