<正>笔者研究了从松材线虫体上分离的2株强致病菌和1株弱致病菌与松材线虫的相互影响。结果表明：强致病菌荧光假单胞菌（Pseudomonasfluorescens）GcM5-1A菌株、恶臭假单胞菌（Pseudomonasputida）ZpBl—2A菌株能够明显地促进无菌松材线虫的产卵量增加、繁殖速度加快和成虫虫体生长；同时，松材线虫也能促进强致病菌荧光假单胞菌GcM5-1A菌株、恶臭假单胞菌ZpB1-2A菌株的繁殖。而泛菌（Pantoeasp?）ZM2C菌株完全抑制了无菌松材线虫的繁殖，无菌松材线虫对泛菌ZM2C菌株的繁殖亦具有显著抑制作用。由此说明松材线虫与其携带的某些致病菌之间存在互惠共生现象，松材线虫携带的致病菌并不是偶然的污染，它们之间的互惠共生现象是在长期共生进化中形成的。笔者还讨论了互惠共生现象在松材线虫致病过程中的作用。

Possessing considerable vendibility,Liriodendron spp. are kinds of important woody and ornamental trees. Researchers have well done lots of research focusing on the basic embryology of breed techniques in Liriodendron spp. for a long time. Concerning embryologicalm researches of Liriodendron spp. in detail, three stages should be divided, that is, descriptive, comparative,and experimental embryology. Most of those researches were focused on the development of male and female gametophyte, the accomplishment of pollination and fertilization, the formation of embryo and endosperm, the construction of seed (including hybrid seed), the separation of sexual cell,and the culture of immature embryo. The results of the general embryological process and hybrid embryology as well as the advances of experimental embryology were summarized in this paper. The prospective strategy for further exploration, which includes generative cell engineering and somatic cell embryogenesis system on this field, was also discussed.