Jingwu Zheng

Length variation and repetitive sequences of Internal Transcribed Spacer of ribosomal RNA gene, diagnostics and relationships of populations of potato rot nematode, Ditylenchus destructor Thorne, 1945 (Tylenchida: Anguinidae)

Seventy-eight ITS rRNA gene sequences obtained from the potato rot nematode, Ditylenchus destructor, collected across the world from different hosts were compared and analysed. The ITS rRNA gene sequences showed significant length variation between populations. The differences in this rRNA fragment length were due to the presence of repetitive elements in the ITS1, which were characterised by relatively higher rates of substitution changes. Reconstruction of secondary structure for the ITS1 revealed that these minisatellites formed a stem structure. Phylogenetic analyses of ITS rRNA and D2-D3 expansion segments of 28S rRNA gene sequences showed that all studied populations clustered in two major clades: a group of populations having the ITS sequences with the repetitive elements and a group of populations without the repetitive elements in the ITS. We propose to distinguish seven ITS rRNA haplotypes within potato rot nematode populations. PCR-ITS-RFLP diagnostic profiles are presented for these ITS haplotypes and usefulness of recently developed PCR methods with species-specific primers for D. destructor are analysed and discussed.

Nematodes threats to global food security

Abstract Presently, more than 925 million people around the world face extreme hunger and 2 billion people lack adequate food security. The first and foremost objective of the millennium development goals (MDGs) set in 2000 is to eradicate extreme poverty and hunger by the year 2015. Three years to the target date, plant–parasitic nematodes pose enormous threats to global food security, destroying at least 12.3% of global food production annually. This is estimated to be more than US

Genomic identification of nitrogen-fixing Klebsiella variicola, K. pneumoniae and K. quasipneumoniae.

157 billion worldwide. Nematode diseases of crops are difficult to control because of the insidious nature of nematodes, and their diagnostic symptoms closely resemble that of other pathogens and abiotic diseases. In order to effectively combat nematodes pests, it is necessary to define the problem in order to correctly search for lasting management strategies. The food insecurity facing millions of people especially in developing countries of Africa, Asia and Latin America is real. Finding lasting solution to this problem presents a daunting challenge for nematologists. The challenges of the future lies in increasing knowledge of nematodes and to use this knowledge in training, research and development (R&D) of new technologies, methods and strategies to be used in effective and sustainable control of the plant parasitic nematodes.

Description of Bursaphelenchus arthuroides sp. n. (Nematoda: Aphelenchoididae), a second parthenogenetic species of Bursaphelenchus Fuchs, 1937

It was difficult to differentiate Klebsiella pneumoniae, K. quasipneumoniae and K. variicola by biochemical and phenotypic tests. Genomics increase the resolution and credibility of taxonomy for closely‐related species. Here, we obtained the complete genome sequence of the K. variicola type strain DSM 15968T (=F2R9T). The genome of the type strain is a circular chromosome of 5,521,203 bp with 57.56% GC content. From 540 Klebsiella strains whose genomes had been publicly available as at 3 March 2015, we identified 21 strains belonging to K. variicola and 8 strains belonging to K. quasipneumoniae based on the genome average nucleotide identities (ANI). All the K. variicola strains, one K. pneumoniae strain and five K. quasipneumoniae strains contained nitrogen‐fixing genes. A phylogenomic analysis showed clear species demarcations for these nitrogen‐fixing bacteria. In accordance with the key biochemical characteristics of K. variicola, the idnO gene encoding 5‐keto‐D‐gluconate 5‐reductase for utilization of 5‐keto‐D‐gluconate and the sorCDFBAME operon for catabolism of L‐sorbose were present whereas the rbtRDKT operon for catabolism of adonitol was absent in the genomes of K. variicola strains. Therefore, the genomic analyses supported the ANI‐based species delineation; the genome sequence of the K. variicola type strain provides the reference genome for genomic identification of K. variicola, which is a nitrogen‐fixing species.

Description of Longidorus hangzhouensis sp. n. (Nemata: Longidoridae) from Zhejiang province, new geographical records of L. henanus Xu & Cheng, 1992, and an identification key for Longidorus species occurring in China.

Bursaphelenchus arthuroides sp. n. is described and figured from pine packaging wood originating in Brazil, and inspected in Ningbo harbour, P. R. China. The new species clearly belongs to the fungivorus group. It is characterised by four lines in the lateral field; spicules medium sized (15-17 μm), dorsal part distinctly sclerotised, with a high rounded condylus and a blunted pointed rostrum in the middle position, capitulum with a shallow depression, the posterior third of the dorsal limb ventrally bent, distal end broadly rounded without cucullus; the shape of the female tail conical and slim, posterior third distinctly ventrally bent with a finely pointed terminus; vulval lips slightly protruding but not forming a vulval flap and post-uterine sac extending for about half the vulva-anus distance. Species status is supported by ITS-RFLP patterns and molecular phylogenetic analysis based on partial LSU sequences, ITS1/2 and partial LSU sequences, which revealed that B. arthuroides sp. n. is closest to B. arthuri. Propagation tests also confirmed that the new species is parthenogenetic.

Interspecific differences in the fine structure of the body cuticle of Trichodoridae Thorne, 1935 (Nematoda: Diphtherophorina) and review of anchoring structures of the epidermis

Specimens of a Longidorus species, here described as L. hangzhouensis sp. n., were recovered from the rhizosphere of sweet-scented Osmanthus growing in Hangzhou, Zhejiang province, China, and a second population was collected from Camellia japonica, Fuyang, Zhejiang province. The species is characterised by medium-sized body length (3.1-4.9 mm), head region narrow (8-12 μm), anteriorly rounded, with continuous, funnel-shaped amphidial pouches, a relatively long odontostyle (97-126 μm) and a short, almost hemispherical tail. Three juvenile development stages were identified, J2, J3 and J4. A second Longidorus species, identified as L. henanus Xu & Cheng, 1990, previously known only from the type locality in Henan province, was recovered from the rhizosphere of bamboo from Beijing and of poplar from Yuanqu county, Shanxi province. A dichotomous key is provided for the Longidorus species reported from China.

Morphological and molecular characterisation of Hemicriconemoides paracamelliae sp. n. (Nematoda: Criconematidae) and two known species of Hemicriconemoides from China

Examination of the fine structure of the body cuticle of Trichodorus cylindricus , T. nanjingensis, T. pakistanensis , T. primitivus, Paratrichodorus anemones , P.hispanus , P.minor , P.pachydermus , P.porosus and P.teres revealed three distinct types, each characterised by differences in layers 4 to 6. A new description is provided for layer 5 and the presence of intracuticular canals and hemidesmosomes as types of anchoring structures for the epidermis are discussed.

Morphological and molecular characterization of Hemicycliophora subbotini n. sp. (Tylenchida: Hemicycliophoridae) from China

Sheathoid nematodes of the genus Hemicriconemoides are migratory root-ectoparasites of many crops but damage is documented for only a few species. Hemicriconemoides paracamelliae sp. n., isolated in Hangzhou, Zhejiang, China, from the rhizosphere of Cinninghamia lanceolata , is described together with H. kanayaensis and H. parataiwanensis . These three species are characterised morphologically and molecularly with important morphological details elucidated by SEM photographs. The new species can be characterised by the en face view having a dorsoventrally orientated oral disc with slit-like opening, and the labial plate being composed of two lateral semi-globular shaped projections on the lateral sides of the oral disc. This new species has the first lip annulus expanded and slightly wider than the second, stylet 83 (80-85) μ m long, excretory pore located 5-6 annuli posterior to the base of the pharyngeal bulb, vulva slit-like, vulval flaps absent, spermatheca rounded to oblong-shaped, and anus located 5-8 annuli posterior to vulva. The tail is elongated, conoid, with the terminal annuli curving dorsally or ventrally to form a finely rounded tip. The study provides the first record of H. kanayaensis from mainland China, a new host association of H. parataiwanensis , and molecular sequencing data of the 18S, 28S D2-D3 and ITS sequences.

Description of a new subspecies of Bursaphelenchus africanus (Nematoda: Aphelenchoididae) found in packaging wood from Russia

Sheath nematodes of the genus Hemicycliophora are migratory root-ectoparasites of many crops, but the damage is documented for only a few species. Hemicycliophora subbotini n. sp., isolated in Hangzhou, Zhejiang, China, from the rhizosphere of camphor tree (Cinnamomum camphora (L.) Presl), is described and characterized morphologically and molecularly with important morphological details elucidated by SEM studies. The new species can be characterized by the conoid lip region, with bulging oral disc protruding beyond the first annulus in some specimens. Oral disc narrow ovate, amphidial apertures covered by lateral plates, lying in the same plane as oral disc when observed en face. Stylet 118 (108-125) μm long and flexible, stylet knobs concave shaped having a slight cavity. The excretory pore is located 1-2 annuli posterior to the base of pharyngeal bulb. Vulval lips slightly modified with small vulval sleeve, spermatheca rounded to oblong. Anus located 18 (15-22) annuli posterior to vulva. Tail elongated, with conoid or slightly offset spike having a narrowly rounded terminus. The study provides the first description of a new Hemicycliophora species from China. Phylogenetic analyses based on D2-D3 expansion segments of the 28S and ITS fragments revealed the new species forming a separate clade from other Hemicycliophora species which supported the status as a new species of this genus.

Description of Longidorus cheni sp. n. (Nematoda, Longidoridae) from China

Bursaphelenchus africanus rossicus subsp. n. was detected from Russian packaging wood (Pinus sp.) arriving in China in August, 2009. The spicule shape and size are almost the same as in the B. africanus found in wood from South Africa, but it differs slightly from the South African isolate by longer (mean L=945 vs 691 μm and 1062 vs 766 μm, for males and females, respectively) and slimmer body (a=39.8 vs 35.0 and 40.0 vs 35.1, for males and females, respectively), higher male ratio c (mean c=37.0 vs 28.7) and higher female ratio c′ (mean c′=4.7 vs 3.4), longer female tail (58 vs 42 μm), and also by female tail shape (slightly ventrally bent vs straight). Their ITS-RFLP patterns are also slightly different. Based on the absence of clear morphological differences and relatively small ITS1/2 and D2/D3 LSU sequence divergences, the new isolate is considered as Bursaphelenchus africanus rossicus subsp. n.