Molecular and biochemical characterization of mungbean yellow mosaic India virus resistance in leguminous host <Emphasis Type="Italic">Vigna mungo</Emphasis>

Mungbean yellow mosaic India virus (MYMIV)—the causal agent of the yellow mosaic disease is responsible for severe damage of crops that are of great economic importance. In the current study, we explored the process of MYMIV infection and its natural resistance by analysing the expression of early and late viral genes at different time points in the leaves of resistant and susceptible Vigna mungo plants. Accordingly, we have periodically evaluated several biochemical parameters commonly associated with oxidative status of resistant and susceptible V. mungo plants during MYMIV infection. Our study revealed that accumulation levels of the early as well as late expressed genes of MYMIV were low and high in the resistant and susceptible plants, respectively; whereas membrane stability index (MSI) exhibited an opposite response. Moreover, a decrease in the malondialdehyde levels along with an increase in the activities/levels of different antioxidant enzymes, total phenol and H₂O₂ was noted during the early stages of infection in the resistant plants. Such observations argue in favour of strong defensive capability of the resistant plants in restricting the accumulation of viral RNA and generation of harmful free radicals within the studied tissue. Collectively, it appears that obstruction of viral invasion in plant cell wall, restriction in viral DNA replication, and early onset of antioxidant defense responses altogether might be responsible for MYMIV natural resistance. Such information is helpful in understanding the pathogenesis of MYMIV infection and its resistance in V. mungo and other economically important crops.     

Environmental analysis of airborne pollen occurrence,pollen source distribution and phenology of <Emphasis Type="Italic">Fraxinus angustifolia</Emphasis>

Narrow-leafed ash (Fraxinus angustifolia) is a common polygamous tree growing on the banks of rivers in the western Mediterranean region. Pollination occurs during winter, and the tree’s pollen is among the most abundant during that season. This work aims to relate the phenology of pollen shedding, source tree distribution, meteorology and airborne pollen occurrence for the species. Aerobiological sampling was conducted in Badajoz (south-western Spain) using a Hirst volumetric sampler over 24 years (1993–2016). Trees were geo-localized in a circle 500 m in diameter surrounding the pollen sampler. During the last two periods, pollination phenology was studied in 10 specimens, five in the surroundings of the pollen station and five 3 km apart, at a frequency of 3–4 days on average. Moreover, a detailed analysis of pollen occurrence was conducted for these two periods. Daily data for the whole period and hourly data over the last 2 years were used, including pollen monitoring and meteorology. A comparison was made between pollen occurrence and source distribution. The main pollen season lasted on average 53 (28–75) days. Average values were less than 10 grains m^?3, except for two periods of 23–24 grains m^?3. Daily data and hourly data correlation with meteorology showed different signs in correlation analysis. Hourly analysis showed that the maximum concentration occurred just after noon. Most pollen was recorded at an average temperature of 9 °C. Analysis of pollen sources and pollen occurrence showed a close relationship between predominant wind directions and tree distribution. Peaks of phenology were not coincident with pollen peaks. No trends in pollination were found. Non-homogeneous distribution of pollen sources for Fraxinus angustifolia provided a suitable tool to demonstrate that wind direction plays a relevant role when aerobiological data are interpreted according to source distribution. A limitation in phenology analysis and aerobiological data was noted in the narrow-leafed ash species.     

<Emphasis Type="Italic">Hymenobacter agri</Emphasis> sp. nov., a novel bacterium isolated from soil

A bacterial isolate was recovered from a soil sample collected in Jeollabuk-do Province, South Korea, and subjected to polyphasic taxonomic assessment. Cells of the isolate, designated strain S1-2-1-2-1^T, were observed to be rod-shaped, pink in color, and Gram-stain negative. The strain was able to grow at temperature range from 10 to 30 °C, with an optimum of 25 °C, and growth occurred at pH 6–8. Comparative 16S rRNA gene sequence analysis showed that strain S1-2-1-2-1^T belongs to the genus Hymenobacter, with closely related type strains being Hymenobacter daeguensis 16F3Y-2^T (95.8% similarity), Hymenobacter rubidus DG7B^T (95.8%), Hymenobacter soli PB^T (95.7%), Hymenobacter terrenus MIMtkLc17^T (95.6%), Hymenobacter terrae DG7A^T (95.3%), and Hymenobacter saemangeumensis GSR0100^T (95.2%). The genomic DNA G+C content of strain S1-2-1-2-1^T was 63.0 mol%. The main polar lipid of this strain was phosphatidylethanolamine, the predominant respiratory quinone was menaquinone-7, and the major fatty acids were C_15:0 iso (27.3%), summed feature 3 (C_16:1 ω7c/C_16:1 ω6c) (16.5%), C_15:0 anteiso (15.3%), and C_16:0 (14.7%), supporting the affiliation of this strain with the genus Hymenobacter. The results of this polyphasic analysis allowed for the genotypic and phenotypic differentiation of strain S1-2-1-2-1^T from recognized Hymenobacter species. On the basis of its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain S1-2-1-2-1^T is considered to represent a novel species of the genus Hymenobacter, for which the name Hymenobacter agri sp. nov. is proposed. The type strain is S1-2-1-2-1^T (=KCTC 52739^T?=?JCM 32194^T).     

Molecular and morphological characterization of the predatory mite <Emphasis Type="Italic">Amblyseius largoensis</Emphasis> (Acari: Phytoseiidae): surprising similarity between an Asian and American populations

The accurate characterization of biological control agents is a key step in control programs. Recently, Amblyseius largoensis from Thailand were introduced in Brazil to evaluate their efficiency for the control of the red palm mite, Raoiella indica. The aim of this study was to confirm their identification and to characterize the population from Thailand, comparing it to populations of the Americas and Indian Ocean islands. In addition, a population of A. largoensis from New Caledonia, Oceania, of which DNA sequences were available, was included in phylogenetic analyses. Morphometric data obtained for the population of A. largoensis from Thailand were compared to those of populations from Reunion Island and the Americas through univariate and multivariate analyses. Two DNA fragments were amplified and sequenced: the nuclear ribosomal region ITSS and the mitochondrial 12S rRNA. Haplotypes (12S rRNA) and genotypes (ITSS) were identified and phylogenetic analyses using both fragments were conducted separately and combined using maximum likelihood and the Bayesian information criterion. The integrative approach reveals morphometric and molecular variabilities among populations of A. largoensis and shows that the population identified as A. largoensis collected in Thailand, as well as that from New Caledonia, are conspecific to the populations of the Americas and Indian Ocean islands. Populations from the Americas and Asia are more related to each other than with that from the Indian Ocean islands. Hypotheses to explain this clustering are proposed. Data on the molecular intraspecific variability of this predatory mite from remote areas will be helpful for the development of molecular diagnosis.     

Productivity and Temperature as Drivers of Seasonal and Spatial Variations of Dissolved Methane in the Southern Bight of the North Sea

Dissolved CH₄ concentrations in the Belgian coastal zone (North Sea) ranged between 670 nmol l^?1 nearshore and 4 nmol l^?1 offshore. Spatial variations of CH₄ were related to sediment organic matter (OM) content and gassy sediments. In nearshore stations with fine sand or muddy sediments, the CH₄ seasonal cycle followed water temperature, suggesting methanogenesis control by temperature in these OM-rich sediments. In offshore stations with permeable sediments, the CH₄ seasonal cycle showed a yearly peak following the chlorophyll-a spring peak, suggesting that in these OM-poor sediments, methanogenesis depended on freshly produced OM delivery. This does not exclude the possibility that some CH₄ might originate from dimethylsulfide (DMS) or dimethylsulfoniopropionate (DMSP) or methylphosphonate transformations in the most offshore stations. Yet, the average seasonal CH₄ cycle was unrelated to those of DMS(P), very abundant during the Phaeocystis bloom. The annual average CH₄ emission was 126 mmol m^?2 y^?1 in the most nearshore stations (~4 km from the coast) and 28 mmol m^?2 y^?1 in the most offshore stations (~23 km from the coast), 1260–280 times higher than the open ocean average value (0.1 mmol m^?2 y^?1). The strong control of CH₄ by sediment OM content and by temperature suggests that marine coastal CH₄ emissions, in particular in shallow areas, should respond to future eutrophication and warming of climate. This is supported by the comparison of CH₄ concentrations at five stations obtained in March 1990 and 2016, showing a decreasing trend consistent with alleviation of eutrophication in the area.     

Estimating hominid life history: the critical interbirth interval

Unlike any great apes, humans have expanded into a wide variety of habitats during the course of evolution, beginning with the transition by australopithecines from forest to savanna habitation. Novel environments are likely to have imposed hominids a demographic challenge due to such factors as higher predation risk and scarcer food resources. In fact, recent studies have found a paucity of older relative to younger adults in hominid fossil remains, indicating considerably high adult mortality in australopithecines, early Homo, and Neanderthals. It is not clear to date why only human ancestors among all hominoid species could survive in these harsh environments. In this paper, we explore the possibility that hominids had shorter interbirth intervals to enhance fertility than the extant apes. To infer interbirth intervals in fossil hominids, we introduce the notion of the critical interbirth interval, or the threshold length of birth spacing above which a population is expected to go to extinction. We develop a new method to obtain the critical interbirth intervals of hominids based on the observed ratios of older adults to all adults in fossil samples. Our analysis suggests that the critical interbirth intervals of australopithecines, early Homo, and Neanderthals are significantly shorter than the observed interbirth intervals of extant great apes. We also discuss possible factors that may have caused the evolutionary divergence of hominid life history traits from those of great apes.     

Similar responses in morphology,growth, biomass allocation,and photosynthesis in invasive <Emphasis Type="Italic">Wedelia trilobata</Emphasis> and native congeners to CO<Subscript>2</Subscript> enrichment

Both global change and biological invasions threaten biodiversity worldwide. However, their interactions and related mechanisms are still not well elucidated. To elucidate potential traits contributing to invasiveness and whether ongoing increase in CO₂ aggravates invasions, noxious invasive Wedelia trilobata and native Wedelia urticifolia and Wedelia chinensis were compared under ambient and doubled atmospheric CO₂ concentrations in terms of growth, biomass allocation, morphology, and physiology. The invader had consistently higher leaf mass fraction (LMF) and specific leaf area than the natives, contributing to a higher leaf area ratio, and therefore to faster growth and invasiveness. The higher LMF of the invader was due to lower root mass fraction and higher fine root percent. On the other hand, the invader allocated a higher fraction of leaf nitrogen (N) to photosynthetic apparatus, which was associated with its higher photosynthetic rate, and resource use efficiency. All these traits collectively contributed to its invasiveness. CO₂ enrichment increased growth of all studied species by increasing actual photosynthesis, although it decreased photosynthetic capacities due to decreased leaf and photosynthetic N contents. Responses of the invasive and native plants to elevated CO₂ were not significantly different, indicating that the ongoing increase in CO₂ may not aggravate biological invasions, inconsistent with the prevailing results in references. Therefore, more comparative studies of related invasive and native plants are needed to elucidate whether CO₂ enrichment facilitates invasions.