小麦蓝矮病植原体转运蛋白secY基因片段序列分析

 Wheat blue dwarf(WBD) is a disease caused by phytoplasma and only reported from China. A fragment about 1.3 kb in protein translocation gene, secY was amplified by PCR from the total DNA of di-seased wheat sample with primer pair secYF/secYR, which was designed based on secY gene sequence of known 16SrI group members. Nucleotide acid sequence analysis of amplified fragment indicated that the length was 1 240 bp. A phylogenetic tree based on secY gene sequences was constructed and showed that wheat blue dwarf phytoplasma was clustered into the Candidatus Phytoplasma asteris, subgroup 16SrI-C. Wheat blue dwarf phytoplasma showed high homology with clover phyllody phytoplasma strains based on sequence comparison and phylogenetic analysis.     

基于叶绿体DNA变异的山荆子种质遗传多样性和系统演化

【目的】山荆子是中国原产苹果属植物中分布最广泛的种,母系遗传的叶绿体基因组的非编码区适用于较低的分类阶元（如科、属）的系统研究。对野外考察新收集的山荆子种质的叶绿体DNA（cpDNA）非编码区进行测序,解析其序列遗传变异,从母系遗传基因的角度探究山荆子不同居群的遗传多样性和系统演化关系,为我国山荆子种质资源的起源演化以及收集和保护提供理论依据。【方法】利用4对叶绿体DNA引物扩增新收集的215份山荆子种质资源的4个非编码区trnH-psbA、trnS-trnG spacer+intron、trnT-5'trnL和5'trnL-trnF,对每个基因间区正反向测序获得的序列进行人工校对后,使用MEGA 7.0进行序列拼接和比对,并构建山荆子不同居群间基于遗传距离的Neighbour-Joining系统发育树;使用DnaSP ver5.10.01计算叶绿体DNA的遗传多样性参数,计算不同居群间的基因流和基因分化;利用Arlequin v3.5分析标准分子变异（AMOVA）;运用NetWork ver4.6.1.2构建种内居群间的叶绿体DNA单倍型邻接网络关联图。【结果】4个叶绿体DNA非编码区经测序、拼接、比对和合并之后的片段长度为3 777 bp,共有171个多态性变异位点,其中包含150个插入-缺失位点、20个简约信息位点和1个单一突变位点。在215份山荆子种质中,trnH-psbA、trnS-trnG spacer + intron、trnT-5'trnL和5'trnL-trnF区域的变异位点数量分别为26、32、103和10个,单倍型数量分别为8、8、6和4个,合并之后的叶绿体DNA片段的单倍型为24个。核苷酸多样性最高的区域为trnT-5'trnL（Pi=0.01174）,单倍型（基因）多样性最高的为trnS-trnG spacer+intron（Hd=0.599）,最低的为5'trnL-trnF（Hd=0.228）。215份山荆子种质叶绿体DNA多样性较高（Hd=0.727,Pi=0.00577）。Tajima’s D检验中,4个cpDNA区域在各检验水平上均不显著,检测的4个cpDNA区域在进化上遵循中性模型。AMOVA分析表明遗传变异主要存在于群体内部。【结论】供试4个叶绿体DNA非编码区适合苹果属山荆子种质遗传多样性和系统演化分析。在叶绿体DNA水平导致山荆子群体进化的原因不是自然选择,而是突变压力和遗传漂变。群体间遗传分化与其地理距离不完全相关。山荆子可能为多点起源,推测黑龙江和吉林,内蒙古,甘肃和山西为3个可能的起源地区。     

竹类植物与水稻等其它禾本科作物的系统进化关系及基因序列组成的比较

利用8个全长mRNA基因序列比较了竹类植物和水稻等禾本科作物的系统进化和序列组成等.结果表明,在与水稻、玉米和麦类作物的比较中,竹类植物与水稻有着最近的亲缘关系和更相似的基因序列特征(GC含量分布和密码子使用频率),它们甚至比水稻与玉米或水稻与麦类之间的亲缘关系更近.这一结果提示,水稻作为禾本科植物的模式物种,应与竹类植物存在良好的基因组共线性关系,水稻基因组序列信息对竹类植物基因组研究与分析具有重要参考价值.     

南天竹过氧化物酶同工酶的研究

采用聚丙烯酰胺凝胶电泳(PAGE)对湖南南天竹13个种质资源的过氧化物酶(POD)同工酶谱进行了分析。依据不同种质间酶带特征的不同,并利用聚类分析的方法,研究了南天竹种质间的亲源关系及遗传多样性。研究表明,这些种质资源共出现10条酶带,所有种质资源都有3条共同特征的谱带,同时不同种质资源酶谱带数目、迁移率(Rf)、酶活性及分布特征均有不同程度的差异,POD酶谱聚类分析将湖南南天竹13个种质分为3大类。     

Evolution of highly pathogenic H7N3 avian influenza viruses in Mexico

Highly pathogenic H7N3 influenza A viruses have persisted in poultry in Mexico since 2012, diversifying into multiple lineages that have spread to three Mexican states, as of 2016. The H7N3 viruses segregate into three distinct clades that are geographically structured. All 2016 viruses are resistant to adamantane antiviral drugs and have an extended 24‐nucleotide insertion at the HA cleavage site that was acquired from host 28S ribosomal RNA.     

Analysis of fungal endophytes in Scottish Sitka spruce plantations shows extensive infections,novel host partners and gives insights into origins

This preliminary study identified the fungal endophytes of Sitka spruce (Picea sitchensis) in four Scottish plantations, analysed their recruitment possibilities and community structure across the sites, and identified the possible origins of the endophytes in this non‐native host. Although Sitka spruce is native to north‐western North America, it comprises a huge portion of Scottish forestry and is an economically vital timber tree. Needles from two age classes were collected and cultured for emerging endophyte isolates. Using a combination of morphological features and genetic sequencing of the nuclear ribosomal ITS regions of representative morphological types, 57 morphotypes were recorded which represented at least 15 different species, including a hypothesized sister species to the pathogen of Pseudotsuga menziesii in North America and Europe, Nothophaeocryptopus gaeumannii (previously P. gaeumannii) that was present at all sites tested. Diversity, recruitment, site, needle age and needle part effects are discussed. The phylogeny of Nothophaeocryptopus based on analysis of combined ITS and Tub2 sequence data is given in order to assess the relationship of the unknown endophyte to the Douglas fir pathogen N. gaeumannii.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

基于rDNA-ITS序列的天门冬拟茎点霉与相似种的系统发育关系

芦笋茎枯病由天门冬拟茎点霉(Phomopsis asparagi)引起,为明确P.asparagi与寄生在其他蔬菜、水果和经济林木等植物上的拟茎点霉不同种之间的系统发育关系,对分离至福建漳州的P.asparagi菌株及从Gen Bank下载的相关菌株的35条ITS序列进行多序列比对分析,并用Neighbor-Joining法构建系统发育树。系统发育分析结果显示:35个菌株被划分为Ⅰ、Ⅱ和Ⅲ组群;P.asparagi与葡萄拟茎点霉(P.viticola)、叶下朱生拟茎点霉(P.phyllanthicola)、杨桃拟茎点霉(P.averrhoae)、大豆茎溃疡病菌(Diaporthe phaseolorum)聚在I组群的A亚群,它们的系统学关系最近;大豆拟茎点霉(P.longicolla)、大豆间座壳菌(Diaporthe sojae)、褐纹拟茎点霉(P.vexans)、光叶子花拟茎点霉(P.glabrae)、柑橘间座壳菌(Diaporthe citri)、黄瓜间座壳菌(Diaporthe sclerotioides)聚在Ⅱ组群,它们与P.asparagi的系统学关系较远;昏暗拟茎点霉(P.obscurans)单独聚在最远的分支上(Ⅲ组群),其与P.asparagi的系统学关系最远。     

3种鼢鼠线粒体DNA控制区结构及其系统发育分析

采用PCR 产物直接测序法测定了3种鼢鼠Mospalax spp.18个个体的线粒体控制区(Control region)核苷酸全序列,并进行了结构分析。通过与仓鼠亚科其他啮齿动物的控制区序列进行比较,将鼢鼠的控制区分为终止序列区、中央保守区和保守序列区3个区域。同时识别了鼢鼠中一系列保守序列,并给出了它们的一般形式。选用普通田鼠Microtus rossiaemeridionalis、褐家鼠Rattus norvegicus、小家鼠Mus musculus、鼹鼠Nannospalax ehrenbergi为外类群,采用NJ和UPGMA法构建分子系统发育树。结果显示：鼢鼠中控制区基因适于系统发育分析,根据分子系统学、形态学的结果初步认为高原鼢鼠M.baileyi和甘肃鼢鼠M.cansus达到了种级地位。