基于染色体特征分析的茄子亲缘关系和系统分类研究

Genetic relationship between species is the theoretical basis for cross breeding. Genetic relationship between relatives and even the classification system for eggplant are still not clearly. Chromosome characteristics of plant are stable cytological characteristics, which can be used as an important basis for species classification, genetic relationship and cultivars identification. The project based on the rich resources of eggplant in our team, we select eight different types of stable inbred lines (including two wild species and six varieties); homology between the genome are analysed by using the GISH comparison of different eggplant that containing repetitive sequence in heterochromatic regions of chromosomes. Small chromosome structure changes and the relationship are concluded by conducting interspecific and intraspecific FISH. The molecular karyotype model of different eggplants can be built via the chromosome morphology and the feature of sequence distribution, then put forward a more scientific and reasonable classification system for eggplant. The results will provide valuable information for the origin and domestication of eggplant, but also advance the plant breeding of Solanaceae and the study of molecular cytogenetics.

物种间的亲缘关系是杂交育种的理论基础，目前对于茄子及其近缘种间的亲缘关系乃至茄子变种间的系统分类问题一直未见定论。植物染色体特征是稳定的细胞学特征，可作为物种分类、亲缘关系辨明和品种鉴定的重要依据。基于前期收集到的丰富资源，本项目选取两份茄子野生种和六份不同类型的茄子稳定自交系，利用GISH比较不同类型茄子富含重复序列的染色体异染色质区域，研究基因组间同源性；开展种间和种内比较FISH，推断种间亲缘关系和种内染色体间的微小结构变化方式；依据染色体形态和序列分布特征构建不同类型茄子的染色体分子核型模式图，进而提出一个较为科学合理的茄子物种的分类系统。结果将为茄子起源和驯化提供有价值的信息，同时也推进基于染色体水平的茄科作物育种和分子细胞遗传学研究。

物种间的亲缘关系是杂交育种的理论基础；植物染色体特征是稳定的细胞学特征，可作为物种分类、亲缘关系辨明和品种鉴定的重要依据。项目基于现代分子细胞遗传学技术对茄子染色体特征及核型进行分析，选取两份茄子野生种和六份不同类型的茄子稳定自交系，优化了茄子体细胞染色体制片技术，获得了染色体浓缩、分散、清晰且背景干净的优良制片，在此基础上开展了基因组原位杂交和荧光原位杂交实验。当供试材料自身基因组与染色体杂交，所有染色体上都具有几乎覆盖整条染色体的杂交信号；当供试材料之间基因组原位杂交时，种内杂交信号分布情况与自身基因组杂交情况类似，而种间杂交信号在染色体间分布有差异；利用核糖体DNA序列和端粒重复序列作为特异探针，进行不同茄子染色体荧光原位杂交，所有茄子均有1对5S rDNA信号，2对25S rDNA信号和2对45S rDNA信号；端粒重复序列在栽培茄和野生茄的所有染色体上均有信号，但染色体间信号有明显差异。综合上述结果，通过分析重复序列和特异序列的信号分布情况，并结合染色体的形态特征对染色体进行排列，构建了栽培茄和野生茄的染色体分子核型图，结果将为茄子亲缘关系研究乃至起源驯化和杂交育种提供理论基础，同时也推进基于染色体水平的茄科作物分子细胞遗传学研究。