Multiplication of the Recombinant Strain Re-7 of Avian Influenza Virus Subtype H5 in MDCK Cells

This study was conducted to explore the multiplication pattern of the recombinant strain Re-7 of avian influenza virus subtype H5 in Madin Darby Canine Kidney(MDCK) cells and to determine the optimal multiplicity of infection(MOI) and the optimal time for virus harvest. The recombinant strain Re-7 was inoculated at different MOIs into MDCK cells grown in serum-free medium in 100 L bioreactors for replication. Then,the hemagglutination(HA) titer, 50% tissue culture infectious dose(TCID50) and 50% embryo infectious dose(EID50) of culture medium were measured once every 12 h from 24 h after virus inoculation to determine the optimal MOI. After that, virus was inoculated at the optimal MOI deter-mined above into MDCK cells for large-scale virus replication to determine the optimal time for virus harvest. The results showed that the optimal MOI was 10~(-2), and the optimal time for virus harvest was 60 h after inoculation. Under these conditions, the HA titer, TCID_(50) per 1 m L and EID50 per 0.1 m L were increased to 1∶102 4, 10~(7.33) and 10~(6.83), respectively. This study provides relatively stable parameters for large-scale production of the recombinant strain Re-7 of avian influenza virus subtype H5.     

Control of insect pests using trunk injection in a newly established apple orchard

We evaluated the potential for using preplant trunk injections of emamectin benzoate in nonbearing apple trees. Trees were evaluated for pest injury and emamectin residues throughout the planting season and into the following year. Injections into the trunk best delivered emamectin benzoate to the canopy compared with injections into the taproot, and the higher rate reduced insect pests more than the lower rate. In the following year, differences in insect control between trunk and root injections were less pronounced, but the higher rate of emamectin benzoate persisted longer and better reduced pests relative to the other treatments.     

Drivers of fine-scale avian functional diversity with changing land use: an assessment of the effects of eco-estate housing development and management

Landscape Ecology - The effects of changing land use, and especially urbanisation, on species and functional diversity are of global concern. Eco-estates are a form of urban housing development...     

How has the state-of-the-art for quantification of landscape pattern advanced in the twenty-first century?

Landscape Ecology - Landscape ecology was founded on the idea that there is a reciprocal relationship between spatial pattern and ecological processes. I provide a retrospective look at how the...     

Molecular identification of blast resistance genes in rice landraces from northeastern India

Rice blast disease caused by the fungus Magnaporthe oryzae is one of the most devastating diseases causing huge losses worldwide. In the present study, major blast resistance genes were investigated in landraces originating from northeastern India. Based on phenotypic evaluation, 288 landraces were classified into three distinct groups: resistant (75), moderately resistant (127) and susceptible (86). The genetic frequencies of the 18 major blast resistance genes were between 6.2% and 27.4%, with only two genotypes possessing a maximum of nine blast resistance genes. The cluster and population structure analysis grouped the landraces into two groups. Through principal coordinate analysis, the scatter plots partitioned the resistant and moderately resistant landraces into different groups. Analysis of molecular variance showed maximum (96%) diversity within populations and least (4%) diversity between populations. Association analysis identified six markers, CRG4_2, RM72, tk59-2, pi21_79-3, RM1233 and RM6648, that are significantly associated with blast disease and explained a phenotypic variance of 1.1–6.5%. The associated genes could be used in marker-assisted rice breeding programmes for gene pyramiding to develop rice varietal resistance against blast disease. The present study represents a valuable blast resistance genetic resource that could be used for identification of new R genes, donors for blast resistance, and genomic studies.     

Control of lettuce big-vein disease by application of fungicides and crop covers

One of the economically important diseases of lettuce is lettuce big-vein disease (LBVD), which leads to severe yield losses. LBVD is associated with a complex of two viruses, Lettuce big-vein associated virus (LBVaV) and Mirafiori lettuce big-vein virus (MLBVV). These viruses are transmitted by motile zoospores of Olpidium spp. fungi, which persist in the soil for decades through resting spores. In greenhouse and field experiments, this study tested whether changing plant and soil temperatures together with fungicide application would have a significant effect on controlling LBVD in lettuce. Soil fumigation with metam sodium was not effective at controlling the disease, as opposed to treatment with chloropicrin and methyl bromide. Moreover, the fungicides carbendazim and fluazinam were effective in reducing the incidence of Olpidium virulentus. Nevertheless, control of the fungal vector did not seem to be sufficient to control the disease due to the transition ability of the virus under low vector abundance. Crop covers, which affect the favourable environmental conditions for the viruses by lowering soil temperature and raising air temperature, reduced the disease symptoms. Combining fungicides with crop cover had a synergistic effect on reducing disease symptoms, thus providing a sustainable solution for LBVD.     

Cryptic species and population genetic structure of Plasmopara viticola in São Paulo State,Brazil

Downy mildew (Plasmopara viticola) is one of the most important diseases in grape-growing areas worldwide, including Brazil. To examine pathogen population biology and structure, P. viticola was sampled during the 2015/16 growing season from 516 lesions on nine grape cultivars in 11 locations in subtropical areas of São Paulo State, Brazil. For identification of cryptic species, a subsample of 130 isolates was subjected to cleaved amplified polymorphic sequence (CAPS) analysis, and for 91 of these isolates the ITS1 region was sequenced. These analyses suggest that the population of P. viticola in São Paulo State consists of a single cryptic species, P. viticola clade aestivalis. Seven microsatellite markers were used to determine the genetic structure of all 516 P. viticola isolates, identifying 23 alleles and 55 multilocus genotypes (MLGs). Among these MLGs, 34.5% were clonal and represented 93% of the isolates sampled. Four dominant genotypes were present in at least five different locations, corresponding to 65.7% of the isolates sampled. Genotypic diversity (Ĝ = 0.21–0.89) and clonal fraction (0.58–0.96) varied among locations (populations). Most populations showed significant deviation from Hardy–Weinberg expectations; in addition, excess of heterozygosity was verified for many loci. However, principal coordinate analysis revealed no clusters among locations and no significant isolation by distance was found, suggesting high levels of migration. The results indicate that downy mildew epidemics result from multiple clonal infections caused by a few genotypes of P. viticola, and reproduction of P. viticola in São Paulo State is predominantly asexual.     

Phytophagous insect fauna of Onopordum spp. thistles in the south of Syria

Thistles from the genus Onopordum (Asteraceae) are of Mediterranean and Eurasian origin. They are very common in the south of Syria, in particular in Damascus and Al Suwayda, and are found in fallow fields, pastures, roadsides and neglected areas. In 2015–2017, several sites with large populations of Onopordum spp. were identified. Weekly surveys of some of the sites, mainly in the regions of Damascus and Al Suwayda, revealed a significant diversity of phytophagous insect species, some of which had a very high population density. A total of 29 insect species were detected, belonging to four orders and 21 families. The most abundant species were from the order Coleoptera. These were observed to be feeding on different plant parts of Onopordum spp. Purely endophagous species comprised 38% of the species observed on Onopordum spp., ectophagous species comprised 45% with 17% of species mixed ectophagous and endophagous. Species that only fed on Onopordum spp. represented 34% of all the species observed.     

Genetic diversity of the pine pathogen Lecanosticta acicola in Slovenia and Croatia

Brown spot needle blight (BSNB), a disease of pine trees caused by the fungus Lecanosticta acicola, has been known in Slovenia since 2008 and in Croatia since 1975. Recent outbreaks in Slovenia prompted this study to compare L. acicola populations in these two neighbouring European countries. Sixty-nine isolates collected from three pine species (Pinus mugo, P. halepensis and P. nigra) were used to determine the phylogenetic relationships, genetic structure, and reproductive strategy of the pathogen. EF1-α sequences showed that Slovenian and Croatian isolates share a common ancestry with individuals from central and northern Europe. Population structure analysis revealed four distinct population clusters of L. acicola in these two countries, generally corresponding to their respective geographic location and host. An unequal ratio of mating types and a low overall genetic diversity in the population indicated a strong influence of asexual reproduction. Although some of the oldest recorded European occurrences of BSNB are from Croatia, this study provided no evidence that the population studied in Croatia was the source of the sampled outbreaks in Slovenia. Recent outbreaks of L. acicola in Slovenia are most likely due to introductions from other, yet to be identified, sources.