Studies on the molecular breeding model by expression vectors

叶绿体和线粒体基因组为农业的重要基因编码。然而，由于它们在大多数情况下是母系遗传的，因此很难通过常规育种方法来改善这些基因组。基于分子生物学的新育种有望帮助改善这些基因组的计划。作为分子育种的典范，我们对水稻叶绿体和线粒体基因组的分子结构进行了分析。构建了水稻叶绿体DNA的物理图谱和重叠克隆库。测定了光合作用重要基因rbcL、atpB/E和psbA的核苷酸序列。通过S_1定位、引物延伸和Northern分析对这些基因的表达进行了研究。利用我们的克隆库，确定了ctDNA的完整核苷酸序列。它是一个圆形，长134,525个碱基。烟草ctDNA中存在的所有基因在水稻中也存在。从稻属野生种稻（Oryza australiensis O. punctata）和稻（o.o officinalis）中分离出叶绿体DNA片段，并将片段克隆为lambda DNA。构建了每个DNA的物理图谱和重叠的克隆库。从水稻（oryza sativa）绿叶中分离线粒体DNA，并将片段克隆为lambda DNA。通过“基因组行走”构建了DNA的遗传和物理图谱。水稻mtDNA的主环长度为528kb。DNA包含许多与ctDNA片段同源的片段。

Chloroplast and mitochondrial genomes code for important genes for agriculture. However, since they are inherited maternally in most cases, it is difficult to improve these genomes by ordinally breeding methods. New breedings based on the molecular biology are expected to help programs to improve these genomes. As a model of the molecular breeding, we have conducted the analysis of molecular structures of chloroplast and mitochondrial genomes in rice.1.Structure of chloroplast DNA from Oryza sativa A physical map and an overlapping clone bank of the ctDNA were constructed. Nucleotide sequences of genes which are important for photosynthesis, rbcL, atpB/E and psbA, were determined. The expression of these genes were also studied by S_1 mapping, primer extension and Northern analysis.2.Complete nucleotide sequence of the ctDNA Using our clone bank, the complete nucleotide sequence of the ctDNA was determined. It is a circular and 134,525 bases long. All genes existed in tobacco ctDNA were also found in rice.3.Cloning of ctDNA from wild species in the genus Oryza Chloroplast DNAs were isolated from Oryza australiensis O. punctata and O.officinalis, and fragments were cloned into lambda DNA. A physical map and an overlapping clone bank of each DNA were constructed.4.Structure of mitochondrial DNA from oryza sativa Mitochondrial DNA was isolated from green leaves of Oryza sativa, and fragments were cloned into lambda DNA. A genetic and physical map of the DNA was constructed by "genome walking". The size of the master circle of mtDNA from rice is 528 kb. The DNA contain many fragments homologous to ctDNA fragments.