Identification and pathogenicity of Neophysopella species associated with Asian grapevine leaf rust in Brazil

Asian grapevine leaf rust (AGLR) causes severe crop losses in Brazilian viticulture, mainly in latitudes <25°S. The purpose of this study was to identify the pathogen(s) involved with AGLR in Brazil, based on phylogenetic and morphological analysis and pathogenicity tests. In total, 56 monouredinial isolates from six Brazilian states were identified using the internal transcribed spacer 2 and the large subunit rRNA gene D1/D2 regions. All 50 isolates from the south-central region were classified as Neophysopella tropicalis, and the other six isolates from the north-east region as Neophysopella meliosmae-myrianthae. This result provides evidence that two pathogen introductions from different sources may have occurred in the country. For both species, paraphyses were cylindrical, incurved, aseptate, and hyaline, while urediniospores were short-pedicellate, obovoid or obovoid-ellipsoid, with the wall colourless or pale yellowish, evenly echinulate. Representative isolates from both species caused typical AGLR symptoms on Vitis vinifera 'Merlot' and V. labrusca 'Niagara Rosada'. Overall, regardless of the Neophysopella species, isolates caused similar leaf disease severities. Higher disease severity was observed in Niagara Rosada (average of 40.3% of diseased leaf area) compared to Merlot (20.5%). This study reports, for the first time, the characterization of Neophysopella species associated with AGLR in Brazil.     

Characterization of Pectobacterium brasiliense strains from potato and vegetables in Israel

Pectobacterium brasiliense (Pbr) infects a wide range of crops worldwide, causing potato blackleg and soft rot and vegetable soft rots. This study aimed to characterize the genetic diversity and virulence variability among 68 Pbr strains isolated from either symptomless potato progeny tubers, diseased potato plants, ware potatoes wash water, or vegetables grown in Israel, as well as strains isolated from symptomless seed tubers grown in Europe, or diseased potato plants grown in France. The collection was typed using PCR and TaqMan real-time PCR analyses, dnaX sequence analysis, pulsed-field gel electrophoresis (PFGE), and pectolytic activity. dnaX phylogeny grouped almost all strains in a common genetic clade related to Pbr, which was distinct from the other Pectobacterium species. PFGE analysis identified two main clusters, including one major group of 47 strains with 95%–100% similarity. Maceration assays on two potato cultivars showed significant differences between strains but with no correlations with the source of the strains nor the status of the host (with/without symptoms). Molecular (dnaX sequences and PFGE profiles) and phenotypic analyses (tuber maceration tests) showed that the tested Pbr strains are not a homogeneous group. Analysis of the tested Pbr strains isolated from potato and vegetables grown in fields with a history of potato cultivation suggests that seed tubers imported from Europe may be the main source for Pbr in Israel. To the best of our knowledge, this is the first study that describes biodiversity and population structure of P. brasiliense isolated from potato and vegetables under hot climate conditions.     

Cryptic diversity,multilocus phylogeny,and pathogenicity of cercosporoid fungi associated with common bean and cowpea

In recent years, common bean (Phaseolus vulgaris) and cowpea (Vigna unguiculata) plants in the north of Iran have exhibited symptoms resembling Cercospora leaf spot (CLS) disease. This study was initiated to elucidate the taxonomy and pathogenicity of cercosporoid taxa associated with leaf spot diseases of these two legume crops in Iran. A total of 138 samples with CLS symptoms were collected from cultivated common bean and cowpea species in northern Iran and subjected to microscopic examination, resulting in identification of 98 Cercospora and 59 Pseudocercospora samples. A six-locus phylogenetic analysis (ITS, actA, tef1, gapdh, his3, and cmdA) coupled with examination of the morphology of 42 representative isolates from these samples confirmed that several cercosporoid fungi occur on common bean and cowpea in Iran. Five Cercospora species (C. iranica, C. cf. flagellaris, Cercospora sp. G, Cercospora sp. T, and C. vignigena) and two Pseudocercospora species (P. griseola f. griseola and P. cf. cruenta) were found; of these, C. cf. flagellaris was the dominant species, occurring on both common bean and cowpea. Pathogenicity tests confirmed that all seven species could infect leaves of common bean and/or cowpea. This is the first report of C. iranica, Cercospora sp. G, and Cercospora sp. T associated with common bean and/or cowpea in the world. In addition, C. vignigena was recorded for the first time in Iran. Results achieved in this study will assist strategies for the management of CLS disease of common bean and cowpea.     

等位基因频率资料的分支分类方法

等位基因频率资料是群体遗传学的重要资料,也是进化生物学的重要资料。本文讨论了利用此类资料重构生物类群系统发育的分支分类方法。常用的分支分类方法为检约性方法和统计分五分类方法。俭约性方法中主要分为三类：数据转换方法、距离叠加树方法和频率空间重建系统发育的方法。同时对不同方法的特点和不足作了讨论。     

鲤CYR61基因的克隆、表达及系统进化树的构建

通过鲤(Cyprinus carpio)基因组序列与斑马鱼(Danio rerio)CYR61基因编码区全序列的比对得到了CYR61 A、CYR61 B和CYR61 C共3条序列。分别克隆、测序得到其开放阅读框(Open Reading Frame,ORF)分别是1 158 bp、1 053 bp、1 107 bp,CYR61 A和CYR61 C得到完整编码区,都是由5个外显子和4个内含子构成,分别编码385、368个氨基酸,其理论等电点值分别是7.83、8.54,分子量(Mw值)分别为42.55 ku、40.83 ku。鲤3个CYR61基因具有高度同源性,并且均含IB、vWC、TSP1、CT 4个模块。分子系统学分析表明鲤CYR61基因与其他物种CYR61基因具有高度同源性,且CYR61 C与其他高等物种的CYR61同源性更高,利用MEGA 5.0计算出CYR61 A、CYR61 B和CYR61 C的分化时间早于鲤和斑马鱼的物种分化。CYR61 C在13个组织中均有表达,在卵巢中表达最高,肠、脑、鳃次之,在其他组织中表达较低且在心脏中表达最低。CYR61 A在精巢、肠、鳃中表达较高。CYR61 B在精巢和脑中表达最高,肠、肌肉、卵巢次之。实时荧光定量PCR分析CYR61 3个复制在鲤胚胎发育时期的表达,都是在0 h相对表达量最高,显著降低至18 h或24 h,随后逐渐升高并在6 d时下降。     

棕黑疣螈种组分子系统发育分析及大围山疣螈新种描述

采用贝叶斯法对棕黑疣螈种组13个个体的线粒体DNA ND2基因重建了系统发育关系,结果表明,（1）该种组物种形成1个单系群;（2）红瘰疣螈不是棕黑疣螈的同物异名,支持红瘰疣螈物种地位的有效性;（3）采自云南省红河州屏边县大围山的2个标本与红瘰疣螈亲缘关系较近,并构成姐妹群,其种间遗传距离已达到种级水平。其地理居群物种为一未描述新种,定名为大围山疣螈。新种的主要鉴别特征为,前肢长于后肢或后肢略长;头部和前后臂为棕黑色,颞部和指、趾端为棕黄色。     

犁鼻器的结构和功能

大多数陆生脊椎动物的鼻腔都有两套化学感受器,即嗅器和犁鼻器。犁鼻器(vomeronasal organ)是临近犁鼻骨的一对盲囊,被覆发达的犁鼻上皮。嗅器主要接受挥发性的小分子物质;犁鼻器主要感受非挥发性的大分子化学物质,如信息素等。犁鼻器在脊椎动物的演化过程中差异明显。鱼类、鳄鱼、鸟类及大多数的蝙蝠和海洋哺乳动物均无犁鼻器;两栖类开始出现犁鼻器;有鳞类和啮齿类的犁鼻器非常发达,且成为一个独立器官。目前,犁鼻器的功能是对陆生环境的特异适应还是对水生环境的适应,仍存在争议。犁鼻器的发生及其功能的研究对于探讨脊椎动物由水生到陆生过程中嗅觉系统的适应进化意义重大。     

Results of molecular analysis of an archaeological hemp (<Emphasis Type="Italic">Cannabis sativa</Emphasis> L.) DNA sample from North West China

Hemp (Cannabis sativa L.) cultivation and utilization is an ancient practice to human civilization. There are some controversies on the origin and subsequent spread of this species. Ancient plant DNA has proven to be a powerful tool to solve phylogenetic problems. In this study, ancient DNA was extracted from an archaeological specimen of Cannabis sativa associated with archaeological human remains from China. Ribosomal and Cannabis specific chloroplast DNA regions were PCR amplified. Sequencing of a species-specific region and subsequent comparison with published sequences were performed. Successful amplification, sequencing and sequence comparison with published data suggested the presence of hemp specific DNA in the archeological specimen. The role of Humulus japonicus Sieb. et Zucc. in the evolution of Cannabis is also indicated. The identification of ancient DNA of 2500 years old C. sativa sample showed that C. sativa races might have been introduced into China from the European–Siberian center of diversity.     

中国鹤虱属(Lappula Moench)分子系统学研究

以黄花软紫草(Arnebia guttata Bunge)和双柱紫草(Coldenia procumbens L.)为外类群,用PAUP*4.0 对鹤虱属(Lappula Moench)13个代表种的核糖体ITS和叶绿体rpS16序列进行分子系统发育分析。采用最大简约法和最大似然法对获得的序列矩阵进行分析,得到一致性进化树。拓扑结构显示,Lappula为单系类群,前人对该属属下阶元的划分带有一定的人为主观性,不能完全真实反映其系统发育关系。结合形态学特征,得出该属植物大致沿着花由小型到大型,果实由同型到异型,小坚果边缘有瘤或刺到具翅这样的路线演化的。     

5种松毛虫翅面鳞片超微结构观察与比较

利用扫描电子显微镜观察马尾松毛虫、油松毛虫、落叶松毛虫、赤松毛虫和思茅松毛虫的翅面鳞片超微结构,发现这5种松毛虫的鳞片分为基鳞与覆鳞2种类型,都属于镂空型鳞片,且为二型双层鳞片。对5种松毛虫的翅面鳞片的长度、宽度、脊间距、最宽处纵脊数进行了测量与比较,形态表征统计分析结果显示:1）鳞片的长宽与翅长不存在显著相关性;2）5种松毛虫的翅面鳞片不存在雌雄间差异,前后翅及翅正反面鳞片均无显著差异;3）种间鳞片宽度、脊间距无显著差异,而长度、最宽处纵脊数均存在显著差异。对翅面鳞片的形态表征进行系统聚类分析,结果显示,同一种松毛虫的不同地理种群之间鳞片大小相似性较高,即同种松毛虫的不同地理种群通常聚为一类。翅面鳞片的超微形态特征不宜单独用于种的鉴定,但可为亲缘关系的研究提供一定的参考。