老班瑶药牛耳风叶绿体基因组特征及其密码子使用偏好性分析

为探究老班瑶药牛耳风叶绿体基因组的结构特征、系统进化以及密码子偏好性,以瑶药牛耳风为研究材料,对其叶绿体基因组进行测序和组装。结果表明,牛耳风叶绿体基因组由大单拷贝区、小单拷贝区以及1对反向重复区组成,全长189 920 bp,包含118个基因,其中99个编码蛋白质的基因,11个tRNA基因,8个核糖体rRNA基因;共检测到71个简单序列重复（simple sequence repeat, SSR）位点。系统进化分析表明牛耳风与番荔枝属的刺果番荔枝（Annona muricata）亲缘关系最近。密码子偏好性分析表明,牛耳风的密码子偏好性较弱,且密码子偏好性主要受选择因素的影响,最终选出11个最优密码子,其中10个以A/U结尾,为瑶药牛耳风的系统进化研究等提供科学依据。     

菠萝叶绿体基因组密码子偏好性分析

叶绿体基因组密码子偏好性影响基因的表达效率,对于叶绿体基因工程应用及物种遗传改良具有重要的科学意义.为了明确菠萝叶绿体基因组密码子偏好性的使用特征及主要影响因素,本研究以菠萝叶绿体基因组为研究对象,利用生物信息学软件分析其密码子的使用模式和偏好性.密码子偏好性相关参数分析显示:(1)菠萝叶绿体基因密码子的GC含量平均值...     

油菜叶绿体DNA的提取和纯化

在吸取了高盐低ｐＨ法分离ｃｐＤＮＡ方法优点的基础上，结合使用３００目、４００目筛网过滤，可以获得具有自然形状的纯净的油菜叶绿体及ＤＮＡ．所得ｃｐＤＮＡ可被限制性内切酶消化．本法操作简便，适于分离完整叶绿体和进行叶绿体的分子生物学研究．     

基于20种桉树叶绿体matK基因序列的系统发育分析

随着公共数据库信息量的不断丰富,桉树基因组序列的公布数据也逐渐增多。本文利用NCBI数据库下载的21条桉树叶绿体matK基因序列进行分析研究,发现软件构建的系统发育树树与学术界承认和使用的Hill＆Johnson形态分类学状态有一定的差异,可能与下载的序列数据不够全面、覆盖的信息量不能代表该种基因组序列有关。通过对MP法、ML法、NJ法、UPGMA法和Bayes法等5种方法构建系统发育树、序列信息位点分析和形态学分类状态的比较,UPGMA法构建的系统发育树与序列的信息位点分析结果较为一致,MP法构建的系统发育树较为可信,但进一步的信息确认还需后续的研究证实。     

Transforming the plastome: genetic markers and DNA delivery systems

Summary Stable chloroplast transformants were first obtained following particle bombardment of tobacco leaves, and later by PEG-mediated uptake of DNA by protoplasts. The transforming DNA in these studies was itself of plastid origin and carried double (streptomycin, spectinomycin) antibiotic resistance which was used to select transformants. Integration was by homologous recombination, and both donor and recipient were Nicotiana species. Recent characterisation of plastid mutants of Solanum nigrum has allowed the extension of this gene replacement approach to include Nicotiana:Solanum combinations.The introduction of functional heterologous genes into the plastome is an alternative approach based on the use of constructs in which a bacterial resistance gene is flanked by sequences homologous to a region of the recipient plastome. Thus homologous recombination in the flanking sequences allows introduction of a foreign gene. A large number of putative transformants can be generated by the method, but this apparent attraction is partly offset by the need for repeated cycles of re-selection to obtain homoplasmic plants. In contrast, homoplasmy can be accomplished in a single selection step using plastome-encoded antibiotic resistance markers.The plastome is an attractive target for the introduction of useful genes into crop plants, as maternal inheritance acts as an insurance against unwanted spread of the foreign gene, and the large plastome copy number ensures immediate gene amplification and may influence levels of expression. Specific characters encoded on the plastid DNA, including components of photosynthesis and other aspects of metabolism, will also become open to manipulation as a consequence of developments in plastid transformation.     

Chromosomal instability in cell- and tissue cultures of tomato haploids and diploids

Summary The effect of the tissue culture system, the genotype and the ploidy level of the plant material used as explant source on the stability of the ploidy level of plants regenerated fromcell and tissue cultures of tomato was investigated. In addition the use of the chloroplast number in guard cells as a measure for ploidy level was evaluated. Haploids of tomato were very instable, which instability was observed already in somatic root tip and leaf cells. The number of regenerated plants that retained the original ploidy level differed significantly between the tested haploids. The plants that were regenerated from leaf explants of diploids were predominantly diploid in contrast to the plants regenerated from established callus cultures and protoplast where the majority was tetraploid.     

Physical mapping of differences between the chloroplast DNAs of Beta vulgaris and B. webbiana

A physical map of Beta webbiana (a wild species of the section Pro-cumbentes) chloroplast genome was constructed by localizing the cleavage sites of SmaI, PstI, PvuII, XhoI, and HindIII, and the map was then aligned with the map of sugarbeet (B. vulgaris) chloroplast DNA. This alignment shows 27 restriction-site changes and 11 insertions/deletions, most of which occur in the large single-copy region of the genome. A 0.7-kb long mutation, located within an unidentified open reading frame (ORF2280) in the inverted repeat, was also found.     

谷子叶绿体基因RNA编辑位点的鉴定与分析

RNA编辑是高等植物叶绿体基因转录后加工修饰的现象,它会影响叶绿体发育,导致植株叶片出现黄化或白化等表型。本研究以长农35号及其2份叶色突变体(E752和E1005)为试验材料,利用紫外分光光度计测定了苗期叶绿素含量,通过透射电镜观察了叶绿体结构;利用在线工具Prep-Cp对谷子叶绿体基因RNA编辑位点进行了预测,通过PCR、RT-PCR及测序等方法对预测到的编辑位点进行了验证,并与其他单子叶作物的编辑位点进行了比较分析;进一步利用荧光实时定量方法,分析rpoB及依赖PEP转录的光合途径相关基因(ndhG、psaA、psbA和rbcL)在不同发育时期的表达水平;最后,利用生物信息学分析ropB编辑前后蛋白二级结构的变化。结果表明,与长农35号相比,2份叶色突变体叶绿素含量显著降低,叶绿体发育异常;在谷子中,有10个叶绿体基因共计20个位点发生RNA编辑,所有编辑位点均为胞嘧啶(C)和尿嘧啶(U)的转换,不同基因的编辑位点存在数量差异,其中ndhB编辑位点数量最多,共计6个; 20个编辑位点中,有19个位点在物种进化上具有较高保守性,只有rpoC1-2753为谷子中特有的编辑位点;在长农...     

盐胁迫对水稻叶片光合效率和叶绿体超显微结构的影响

研究了NaCl胁迫下耐盐性不同的水稻品种Pokkali(耐盐)和Peta(盐敏感)叶片光合效率和叶绿体数量和结构的变化。结果表明：随着NaCl胁迫浓度和时间的增加，耐盐品种单位面积的叶绿体数目变化不大，盐敏感品种叶绿体数目明显减少；叶绿体老化加快，基粒片层和基质片层逐渐解体，嗜锇颗粒数量和体积逐渐增加，耐盐品种叶绿体伤害程度明显小于盐敏感品种。耐盐品种Pokkali叶绿体结构在盐胁迫下的稳定性明显强于盐敏感品种Peta。耐盐品种净光合速率和PSⅡ光化学效率(FV／Fin)下降的幅度小于盐敏感品种。     

谷子条纹叶突变体A36-S的细胞学特性分析及基因定位

【目的】谷子是C₄模式植物,其叶色突变体是研究C₄光合途径的良好材料。通过研究谷子条纹叶突变体A36-S的细胞学特性并对突变基因进行定位,为克隆突变基因、解析谷子叶绿体合成及发育机理、进一步理解C₄光合调控机制奠定基础。【方法】谷子条纹叶突变体A36-S是由育种创制的中间材料A36自然变异而来。对比A36-S及其正常表型等基因系A36-N的表型特征,调查二者的株高、叶宽、叶长、穗重、千粒重、结实率等农艺性状指标;测定A36-S和A36-N的叶绿素含量、净光合速率、胞间CO₂浓度、气孔导度、蒸腾速率等光合指标,分析A36-S的光合特性;观察A36-S和对照品种豫谷1号的叶片半薄横截切片和超薄切片,分析A36-S叶片解剖结构特征,分别统计叶肉细胞和维管束鞘细胞中叶绿体的数量和面积,从而分析叶绿体合成及发育情况;构建A36-S×SSR41的F₂分离群体,统计群体中正常表型单株与条纹叶单株的数量,进行遗传分析;分别构建F₂分离群体正常单株与条纹叶单株的DNA混池,采用集团分离分析法（BSA法）进行突变基因的定位;筛选、开发多个SSR标记及In-Del标记,扫描F₂群体中条纹叶单株,进行进一步基因定位。【结果】谷子条纹叶突变体A36-S在全生育期表现出叶片不规则白色条纹的表型。农艺性状分析表明,相比其近等基因系A36-N,A36-S在株高、叶宽、穗重、千粒重、结实率等表型上均显著下降。光合指标测定表明A36-S叶片中叶绿素含量明显降低,尤其是叶绿素b含量下降更为严重,同时净光合速率也明显下降。叶片解剖结构观察发现,与对照豫谷1号相比,A36-S的Kranz结构变化并不明显,但叶绿体数量和大小都显著低于对照。观察叶绿体超微结构,发现A36-S的不同细胞间叶绿体发育状况差异较大,依据叶绿体发育情况可将叶片细胞可分为3类：Ⅰ类细胞具有正常发育的叶绿体;Ⅱ类细胞叶绿体基粒及片层结构减少;Ⅲ类细胞则叶绿体结构严重异常甚至不含有叶绿体。遗传分析表明A36-S表型受隐性单基因控制,利用F₂分离群体将突变基因定位在第4染色体7.66—27.90 Mb区间内。【结论】谷子A36-S条纹叶突变体表现为农艺性状及光合能力下降,叶片细胞叶绿体的数量、大小及结构均表现出显著异常。条纹叶性状受隐性单基因控制,利用分子标记将候选基因定位于第4染色体7.66—27.90 Mb区间内。