橐吾属的杂交物种形成研究—莲叶橐吾和穗序橐吾的自然杂交
余姣君
学位类型硕士
导师龚洵
2010-11
学位授予单位中国科学院研究生院
学位专业植物学
摘要在香格里拉县的一次野外考察中,发现一片火烧迹地上,同域分布有多种橐吾属(Ligularia Cass.)植物:穗序橐吾(L. subspicata)、莲叶橐吾(L. nelumbifolia)、东俄洛橐吾(L. tongolensis)、舟叶橐吾(L. cymbulifera)、君范橐吾(L. lingiana)等,还有少数形态上介于穗序橐吾和莲叶橐的个体。因此,在野外初步判断这些个体为二者的自然杂交后代,依据形态将它们假设为杂交种A和B,并持续进行了深入调查。通过查阅相关类群的标本,并且与研究对象标本做细致的比较,假设杂交种A花序近于莲叶橐吾,但叶形界于穗序橐吾和莲叶橐吾之间;假设杂交种B与莲叶橐吾最接近,但花序颜色与穗序橐吾一致。相比莲叶橐吾(39%)和穗序橐吾(36.8%),假设杂交种B(45.7%)的种子萌发率略高,而假设杂交种A的极低(0.3%),假设杂交A育性低的一个可能的解释就是杂交。本研究共采集假设亲本及周围的橐吾、假设杂交种A和B共60个个体,对4个叶绿体片段测序, ITS4-5片段直接测序或克隆测序。结果支持莲叶橐吾和穗序橐吾是杂交种A的亲本,但大部分个体的母本是穗序橐吾,棉毛橐吾也可能参与了部分杂交;假设杂交种B的核序列没有叠加性,且叶绿体片段与莲叶橐吾一致,不支持杂交B的假设;而假设亲本穗序橐吾中还存在回交的个体。ISSR标记用NewHybrids分析后,假设杂交种A的个体基本是莲叶橐吾和穗序橐吾的杂交F1代个体(10/11),只有1/11可能发生回交或其它形式的杂交;杂交B的个体全部100%的概率是莲叶橐吾;亲本个体除了穗序橐吾1个个体可能是被回交外,其它判断的可信度都是100%。本研究着重于分子证据,辅之生态、生殖等特征,判断了一个混合居群中的形态中间个体是杂交的可能性以及杂交的所属类群的可能性。结论为莲叶橐吾和穗序橐吾是假设杂交种A个体的亲本,且大部分是以穗序橐吾为母本的形式的杂交,棉毛橐吾也可能参与了极少数个体的杂交,杂交个体主要以F1代形式存在;有少部分个体发生了回交,且从花期判断,回交最可能发生在穗序橐吾中;杂交种B的假设不成立。
资助项目During a field trip at a brule in Shangri-La, a mixed population of Ligularia Cass. was found, which including L. subspicata (Bur. et Franch.) Hand.-Mazz., L. nelumbifolia (Bur. et Franch.) Hand.-Mazz., L. tongolensis (Franch.) Hand.-Mazz., L. cymbulifera (W.W.Smith) Hand.-Mazz., L. lingiana S.W.Liu, and also some individuals morphologically intermediate between L. subspicata and L. nelumbifolia. Hence, these intermediate individuals were preliminarily assumed as natural hybrids of the two Ligularia. According to their morphology, they’re assumed to form hybrids A and B. Through careful comparison of specimens in herbarium and those we collected, the inflorescence of putative hybrid A is close to L. nelumbifolia, but the shape of laminae are intergradation of L. subspicata and L. nelumbifolia; overall morphology of putative hybrids B is similar to L. nelumbifolia, but inflorescence color is as same as L. subspicata. Compared to L. nelumbifolia (39%) and L. subspicata (36.8%), the germination rate of putative hybrid B (45.7%) slightly higher than the two; but that of hybrid A is extraordinarily low (0.3%). One possible interpretation of the low rate is hybridization. 60 individuals were collected, including putative parents, other 4 species of Ligularia nearby, putative hybrid A and B. They were all direct sequenced of four cpDNA fragments, and direct sequenced or cloning sequenced of nrDNA ITS4-5. The results support that L. nelumbifolia and L. subspicata are parents of putative hybrid A, and the majority female parent is L. subspicata, L. vellerea may also be involved in the hybridization in some degree; the nuclear sequences of putative hybrid B have no superposition, and its chloroplast DNA sequences are identical with L. nelumbifolia, so putative hybrid B could not be hybrid; and there are backcross individuals exist among the putative parent L. subspicata. NewHybrids analysis of ISSR markers indicated that, the individuals of putative hybrid A are almost L. nelumbifolia and L. subspicata F1 hybrid generation (10/11), only 1/11 possibly backcross or other forms; all individuals of hybrid B are L. nelumbifolia; except one individual of L. subspicata as backcrossed, the other parent individuals are 100% reliable. This study focused on molecular evidence, complemented by ecological, reproductive and other characteristics, we demonstrated that the morphologically intermediate individuals’ origin, and the probability of belonging to each parental or hybrid class. And concluded that L. nelumbifolia and L. subspicata are the parents of putative hybrid A, L. vellerea may also be involved in the hybridization in some degree, hybrids mainly are the first generation, a few individuals may be involved in backcross, and most probably backcross with L. subspicata according to the anthesis, while the assumption of hybrid B is not supported.
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/16034
专题昆明植物所硕博研究生毕业学位论文
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余姣君. 橐吾属的杂交物种形成研究—莲叶橐吾和穗序橐吾的自然杂交[D]. 中国科学院研究生院,2010.
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