茉莉酸信号受体COI蛋白家族的分子进化与基因表达分析

茉莉酸(Jasmonic acid,JA)存在于所有高等植物中,是植物对病原微生物和虫害防御反应的关键激素。在茉莉酸信号转导中,COI1(COR-insensitive 1)作为茉莉酸信号受体蛋白在其中发挥关键作用。本研究采用生物信息学方法,从藻类、苔藓类、蕨类、裸子及单、双子叶植物多谱系对COI蛋白家族进行比较基因组学研究,并取得以下结果:(1)同源基因鉴定结果发现,在所选的7种陆生植物中一共鉴定了55个COIs同源基因,然而,在低等的水生植物包括绿藻类(Chlorophytes)、红藻类(Rhodophytes)、硅藻类(Bacillariophytes)、灰胞藻类(Glaucophytes)及褐藻类(Phaeophytes)等基因组中均未发现其同源基因;(2)系统进化树分析表明,植物COI蛋白家族可以分为4个保守的亚家族,且在陆生植物扩增的同时可能已发生功能分化;(3)基因结构分析显示,植物COI家族基因结构表现多样性,主要体现在内含子的数目和长度上;(4)基因表达数据提示,COI基因家族成员参与植物生长发育的多个时期,且在不同组织器官以及不同的胁迫应答反应中发挥不同的作用。以上结果将为植物COI基因家族的深入研究提供参考。     

Molecular identification of mosquitoes (Diptera: Culicidae) in southeastern Australia

DNA barcoding is a modern species identification technique that can be used to distinguish morphologically similar species, and is particularly useful when using small amounts of starting material from partial specimens or from immature stages. In order to use DNA barcoding in a surveillance program, a database containing mosquito barcode sequences is required. This study obtained Cytochrome Oxidase I (COI) sequences for 113 morphologically identified specimens, representing 29 species, six tribes and 12 genera; 17 of these species have not been previously barcoded. Three of the 29 species ─ Culex palpalis, Macleaya macmillani, and an unknown species originally identified as Tripteroides atripes ─ were initially misidentified as they are difficult to separate morphologically, highlighting the utility of DNA barcoding. While most species grouped separately (reciprocally monophyletic), the Cx. pipiens subgroup could not be genetically separated using COI. The average conspecific and congeneric p‐distance was 0.8% and 7.6%, respectively. In our study, we also demonstrate the utility of DNA barcoding in distinguishing exotics from endemic mosquitoes by identifying a single intercepted Stegomyia aegypti egg at an international airport. The use of DNA barcoding dramatically reduced the identification time required compared with rearing specimens through to adults, thereby demonstrating the value of this technique in biosecurity surveillance. The DNA barcodes produced by this study have been uploaded to the ‘Mosquitoes of Australia–Victoria’ project on the Barcode of Life Database (BOLD), which will serve as a resource for the Victorian Arbovirus Disease Control Program and other national and international mosquito surveillance programs.     

Effects of habitat fragmentation on genetic diversity and gene flow among the Homidia socia (Collembola: Entomobryidae) populations in the Thousand Island Lake

In the present study, partial sequences of the mitochondrial cytochrome oxidase subunit I (COI) gene of 22 island populations of the springtail Homidia socia in the Thousand Island Lake were sequenced. Across all sequences, 37 haplotypes were identified for the 510‐bp mitochondrial (mt) DNA COI gene. Haplotype 2 was the most common, and was distributed in the most of the 22 island populations. Haplotype diversity ranged from 0.065 to 0.733, and the total genetic diversity was 0.56216. The genetic characteristics of the 22 island populations were analyzed using the fixation index and gene flow, with values of 0.00043–0.94900 and 0.02703–703.72540, respectively. Comparison between (island area and isolations) with population genetic diversity revealed that there were no significant correlations between them, except for a significant correlation between the number of haplotypes and island area. Mantel tests showed that there was no significant correlation between geographic distance and genetic distance among various groups. All the results indicated that there were no obvious relationships between island characteristics and the genetic diversity of the springtails. We consider that the low dispersal capacity of springtails and the island patches surrounded by water in the Thousand Island Lake are the major factors affecting the genetic diversity of H. socia.     

Genetic divergence of Platycerus hongwonpyoi (Coleoptera: Lucanidae) in South Korea

We examined the genetic divergence of Platycerus hongwonpyoi Imura & Choe, 1989 in South Korea using the nuclear wingless (Wg) gene, internal transcribed spacer (ITS) region and mitochondrial cytochrome oxidase subunit I (COI) gene. We found no variation in Wg or ITS. Based on COI, P. hongwonpyoi was split into four well defined and one weakly supported clades, which were inferred to have diverged 2.11–1.33 Ma. The Platycerus hongwonpyoi population size seems to have decreased during the past several tens of thousands of years. The divergence times of major clades of P. hongwonpyoi were comparable with those involved in the speciation of certain Japanese species. Frequent overlapping of different clades at the same sites suggests the occurrence of secondary gene flow following differentiation in South Korea. In conclusion, the genus Platycerus underwent strikingly different divergence patterns in South Korea compared with Japan according to the disparate topographies of these two geographical areas.     

Exploring taxonomic diversity and biogeography of the family Nemacheilinae (Cypriniformes)

Nemacheilidae, in the superfamily Cobitoidea, is comprised of many of morphologically similar fish species that occur in Eurasian water bodies. This large group shows inconsistencies between traditional morphological taxonomy and molecular phylogenetic data. We used mitochondrial genomes, recombinase‐activating gene proteins 1 (RAG1) and the mitochondrial cytochrome c oxidase I gene (COI) to study the phylogenetic relationships among Nemacheilidae species using Bayesian inference and maximum likelihood approaches. Phylogenetic analyses based on mitogenomes provided support for two clades (I and II). The mitogenomes, RAG1, and COI results indicated that several species and genera were not consistent with the traditional morphological subdivisions. The two clades inferred from mitogenomes showed clear geographical patterns. The Tibetan Plateau, Hengduan Mountains, and the Iran Plateau may act as a barrier dividing the clades. The estimated timing of clades separation (36.05 million years ago) coincides with the first uplift of the Tibetan Plateau. We conclude that the geological history of the Tibetan Plateau played a role in the diversification and distribution of the Nemacheilidae taxa. These results provided a phylogenetic framework for future studies of this complex group.     

Mitochondrial DNA genomes of five major Helicoverpa pest species from the Old and New Worlds (Lepidoptera: Noctuidae)

Five species of noctuid moths, Helicoverpa armigera, H. punctigera, H. assulta, H. zea, and H. gelotopoeon, are major agricultural pests inhabiting various and often overlapping global distributions. Visual identification of these species requires a great deal of expertise and misidentification can have repercussions for pest management and agricultural biosecurity. Here, we report on the complete mitochondrial genomes of H. assulta assulta and H. assulta afra, H. gelotopoeon, H. punctigera, H. zea, and H. armigera armigera and H. armigera conferta’ assembled from high‐throughput sequencing data. This study significantly increases the mitogenome resources for these five agricultural pests with sequences assembled from across different continents, including an H. armigera individual collected from an invasive population in Brazil. We infer the phylogenetic relationships of these five Helicoverpa species based on the 13 mitochondrial DNA protein‐coding genes (PCG's) and show that two publicly available mitogenomes of H. assulta ( KP015198 and KR149448 ) have been misidentified or incorrectly assembled. We further consolidate existing PCR‐RFLP methods to cover all five Helicoverpa pest species, providing an updated method that will contribute to species differentiation and to future monitoring efforts of Helicoverpa pest species across different continents. We discuss the value of Helicoverpa mitogenomes to assist with species identification in view of the context of the rapid spread of H. armigera in the New World. With this work, we provide the molecular resources necessary for future studies of the evolutionary history and ecology of these species.     

Molecular phylogeography of two sibling species of <Emphasis Type="Italic">Eurema</Emphasis> butterflies

The common yellow butterfly Eurema hecabe is widely distributed in East Asia, and is one of the most burdensome species for taxonomists due to the numerous geographic and seasonal wing colour patterns. Moreover, within this species, individuals with a yellow wing fringe that occur in temperate regions of Japan (Y type) proved to be biologically different from others that occur widely in subtropical regions of Japan and all over East Asia (B type). To unveil the genetic variation within and between the two types, a total of 50 butterflies collected at 18 geographic localities in East Asia were examined for nucleotide sequence variation of three mitochondrial regions: cytochrome c oxidase subunit I (COI), cytochrome c oxidase subunit III (COIII) and NADH dehydrogenase subunit 5 (ND5). In addition, they were also examined for infection status with the endosymbiotic bacteria Wolbachia. The three mitochondrial sequences consistently showed that (i) Y type and B type were highly divergent, (ii) nucleotide variation within B type was very small although sampled from a geographically wide range, and (iii) a weak association existed between mitochondrial DNA haplotypes and Wolbachia infection status.     

Species Identification of Tarantulas using Exuviae for International Wildlife Law Enforcement

This paper outlines a novel, non-invasive procedure to obtain DNA from Mexican tarantulas (Brachypelma spp.) using exuvia. These species are important in the pet trade and species identification is important for international wildlife law enforcement. Mitochondrial DNA sequence from the cytochrome c oxidase subunit I gene was used to investigate the relationship between various Brachypelma spp. This phylogeny was used as a framework to assign unknown specimens and spiderlings to species. The benefits to conservation, research, and international wildlife law enforcement that are gained by the ability to accurately identify species without the death of the specimen are explored. Our data also suggest that there is no support for the genus Brachypelmides as some authors have proposed and upholds the synonymy of Locht et al. (1999) J Arachnol 27:196–200.     

Comparison of pheromone trap design and lures for Spodoptera frugiperda in Togo and genetic characterization of moths caught

Fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), is a pest of grain and vegetable crops endemic to the Western Hemisphere that has recently become widespread in sub‐Saharan Africa and has appeared in India. An important tool for monitoring S. frugiperda in the USA is pheromone trapping, which would be of value for use with African populations. Field experiments were conducted in Togo (West Africa) to compare capture of male fall armyworm using three commercially available pheromone lures and three trap designs. The objectives were to identify optimum trap × lure combinations with respect to sensitivity, specificity, and cost. Almost 400 moths were captured during the experiment. Differences were found in the number of S. frugiperda moths captured in the various trap designs and with the three pheromone lures, and in the number of non‐target moths captured with each lure. The merits of each trap × lure combination are discussed with respect to use in Africa. A nearly equal number of COI‐CS (161) and COI‐RS (158) moths was captured with no differences found in COI marker proportions among traps or lures. However, the diagnostic rice strain marker Tpi was rarely found. Overall, the genetic characterization of the pheromone trap collections indicated a consistent distribution of genetic markers from 2016 to 2017, suggesting a population at or near equilibrium.