A new catfish of the genus Trichomycterus from the Rio Paraíba do Sul Basin, south-eastern Brazil, a supposedly migrating species (Siluriformes, Trichomycteridae)

A new species of the catfish genus Trichomycterus is described from the Rio Paraíba do Sul, south-eastern Brazil. This species exhibits some morphological character states that are unique amongst congeners, including a robust opercle and a long interopercle with numerous odontodes (50–60 opercular and 90–100 interopercular), a black bar on the basal portion of the caudal fin and a dark brown flank with a well delimited dorsal yellow stripe. It also exhibits some morphological traits that are uncommon amongst congeners, such as the presence of nine pectoral-fin rays. The presence of a shallow hyomandibular outgrowth and a ventrally expanded pre-opercular ventral flap suggests that this species is closely related to T. melanopygius, T. pradensis and T. tete. The new species also differs from T. melanopygius, T. pradensis and T. tete by having an emarginate caudal fin and a single median supra-orbital pore S6. Anecdotal evidence suggests that T. largoperculatus and T. pradensis have migratory habits, a condition not previously reported for eastern South American trichomycterines.

Application of Multiplex TaqMan Real-Time PCR Assay in Survey of Five Lily Viruses Infecting Lilium spp.

Lily symptomless virus (LSV), Lily mottle virus (LMoV), Cucumber mosaic virus (CMV), Shallot yellow stripe virus (SYSV), and Plantago asiatica mosaic virus (PlAMV) are five of the economically important viruses infecting lilies (Lilium spp.) worldwide. In order to prevent the occurrence and spread of these viruses, it is necessary to develop a rapid, effective, and sensitive detection method for the simultaneous detection and specific quantification of these viruses. In this study, specific primers and probes for multiplex TaqMan real-time PCR assays designed from conserved regions of the coat protein sequence of each virus were used for the simultaneous detection of these viruses in lilies (Lilium spp.). The optimal concentration of primers and probes and reaction annealing temperature were 20 µM and 55.9 °C, respectively. The detection limits of the assay were 1.33 × 102, 1.27 × 101, 1.28 × 101, 2.33 × 102, and 2.01 × 102 copies·μL−1 for LSV, LMoV, CMV, SYSV, and PlAMV, respectively. Specificity was determined using seven viral pathogens of lilies. Variability tests of intra- and inter-assays showed high reproducibility with coefficients of variation <2%. The multiplex TaqMan real-time PCR assay was used to detect these viruses from lily samples in China. In brief, our developed assay showed high specificity, sensitivity, and reproducibility for the simultaneous detection and differentiation of five lily-infecting viruses and can be used for certification and quarantine programs.

Analysis of Host-Specific Differentiation of Puccinia striiformis in the South and North-West of the European Part of Russia

Yellow (stripe) rust, caused by Puccinia striiformis Westend. (Pst), is a major disease of cereals worldwide. We studied Pst virulence phenotypes on Triticum aestivum, Triticum durum, and triticale in three geographically distant regions of the European part of Russia (Dagestan and Krasnodar in North Caucasus, and Northwest) with different climate and environmental conditions. Based on the set of twenty differential lines, a relatively high level of population diversity was determined with 67 different Pst pathotypes identified among 141 isolates. Only seven pathotypes were shared by at least two hosts or occurred in the different regions. No significant differentiation was found between regional Pst collections of pathotypes either from T. aestivum or from T. durum. A set of Pst pathotypes from triticale was subdivided into two groups. One of them was indistinguishable from most durum and common wheat pathotypes, whereas the second group differed greatly from all other pathotypes. All sampled Pst isolates were avirulent on lines with Yr5, Yr10, Yr15, and Yr24 genes. Significant variation in virulence frequency among all Pst collections was observed on lines containing Yr1, Yr3, Yr17, Yr27, and YrSp genes and cvs Strubes Dickkopf, Carstens V, and Nord Desprez. Relationships between Russian regional collections of Pst from wheat did not conform to those for P. triticina.

Detection and Distribution of Viruses Infecting Garlic Crops in Australia

The distribution of viruses in eastern Australian field garlic was evaluated. Detection assays were developed that involved generic RT-PCR for viruses in the Allexivirus, Carlavirus and Potyvirus genera followed by virus-specific colorimetric dot-blot hybridization. Assays targeted the potyviruses (onion yellow dwarf virus (OYDV), shallot yellow stripe virus (SYSV), and leek yellow stripe virus (LYSV)), the carlaviruses (garlic common latent virus (GCLV) and shallot latent virus (SLV)), and the allexiviruses (garlic viruses A, B, C, X (GarVA, -B, -C, -X) and shallot virus X (ShVX)). Virus incidence in crops was consistently high, with most plants infected with at least one virus from each genus. OYDV, LYSV, SLV, and GCLV were commonly detected. Three of the four allexiviruses were in all districts surveyed but varied in incidence, whereas ShVX and SYSV were not detected. There was no association between virus species complement and bulb size, indicating size is not a good predictor of the virus status of planting material. The variation of virus incidence across different Australian growing districts and in different cultivars implies multiple introductions of viruses rather than spread within the country. The genetic diversity observed within coat protein sequences of some virus species also supports multiple separate introductions.

Phylogenetic and diversity analyses revealed that leek yellow stripe virus population consists of two types: S and N

Leek yellow stripe virus (LYSV, Potyvirus), a pathogen affecting Allium spp. worldwide, has been suspected to consist of two types: S and N, based on genetic and host species differences. In this study, phylogenetic and evolutionary analyses were performed to P1 and CP regions of genome of global LYSV isolates to clarify the variation among members of S-type and N-type. Constructed phylogenetic trees clearly divided isolates into S-type and N-type, with N-type was further split into L and N groups, according to hosts. Significant nucleotide (nt) and amino acids (aa) sequence variation were observed on full ORF, P1, HC-Pro, P3, VPg coding regions. The dN/dS values of P1 and CP confirmed that both genes are under strong negative selection pressure. Neutrality tests on Eastern Asian isolates argued that ancestor of current LYSV isolates may had evolved with garlic while they were in Asia before spread to other world regions through garlic propagative materials. The genetic differentiation and gene flow analysis showed that there was very frequent gene flow from S-type to L and N groups and these phylogroups differentiated from each other over time. Host differences, substantial nt and aa variation, inconsistent serological test results, and phylogenetic and diversity analyses results highly suggested that LYSV can be separated into two types: S and N.