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Peronospora tabacina is an obligate parasite that causes blue mold of tobacco. The pathogen reproduces primarily by sporangia, whereas the sexual oospores are rarely observed. A collection of 122 isolates of P. tabacina was genotyped using nine microsatellites to assess the population structure of individuals from subpopulations collected from central, southern, and western Europe; the Middle East; Central America; North America; and Australia. Genetic variations among the six subpopulations accounted for ∼8% of the total variation, including moderate levels of genetic differentiation, high gene flow among these subpopulations, and a positive correlation between geographic and genetic distance (r = 0.225; P < 0.001). Evidence of linkage disequilibrium (P < 0.001) showed that populations contained partially clonal subpopulations but that subpopulations from Australia and Mediterranean Europe did not. High genetic variation and population structure among samples could be explained by continuous gene flow across continents via infected transplant exchange and/or long-distance dispersal of sporangia via wind currents. This study analyzed the most numerous P. tabacina collection and allowed conclusions regarding the migration, mutation, and evolutionary history of this obligate biotrophic oomycete. The evidence pointed to the species origin in Australia and identified intracontinental and intercontinental migration patterns of this important pathogen.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Micro-organisms form the first pioneer community in the history of biological life, thought to be present in the primordial soup and evolving later with more complex life-forms. Among micro-organisms, viruses form a separate taxon of organisms. Viruses are obligate parasites, being inactive without a host and becoming active once in contact with specific hosts. Viruses, with an inherent ability to infect and hijack cellular structures, have been utilised as vectors to introduce foreign genetic material in a variety of biological species, e.g. adenoviral vectors. However, viruses have also been the root cause of many infectious diseases, most notable being HIV-AIDS, for its resistance to treatment and omnipresent occurrence. There are many families of viruses like retroviridae, picornaviridae and poxviridae. This review focuses on a specific member of the coronaviridae, the SARS-CoV-2. This virus is responsible for the current COVID-19 pandemic. This review summarises its transmission, molecular mechanism by which it causes disease, associated clinical symptoms and the strategies available to control it from sources like PubMed, Google Scholar, webservers of National Institute of Health (NIH), European Molecular Biology Laboratory (EMBL), World Health Organisation (WHO), United States Food and Drug Administration (USFDA) and Centers for Disease Control and Prevention (CDC) available as on 1st May 2021.

Premise A subset of parasitic plants bear extremely reduced features and grow nearly entirely within their hosts. Until recently, most of these endoparasites were thought to represent a single clade united by their reduced morphology. Current phylogenetic understanding contradicts this assumption and indicates these plants represent distantly related clades, thus offering an opportunity to examine convergence among plants with this life history. Methods We sampled species from Apodanthaceae, Cytinaceae, Mitrastemonaceae, and Rafflesiaceae spanning a range of developmental stages. To provide a broader comparative framework, Santalaceae mistletoes with a similar lifestyle were also analyzed. Microtomography and microscopy were used to analyze growth patterns and the ontogeny of host-parasite vascular connections. Results Apodanthaceae, Cytinaceae, Mitrastemonaceae, and Rafflesiaceae species demonstrated a common development characterized by late cell differentiation. These species were also observed to form direct connections to host vessels and to cause severe alterations of host xylem development. Apodanthaceae and Rafflesiaceae species were additionally observed to form sieve elements, which connect with the host phloem. Endophytic Santalaceae species demonstrated a dramatically different developmental pattern, featuring early cell differentiation and tissue organization, and little effect on host anatomy and cambial activity. Conclusions Our results illuminate two distinct developmental trajectories in endoparasites. One involves the retention of embryonic characteristics and late connection with host vessels, as demonstrated in species of Apodanthaceae, Cytinaceae, Mitrastemonaceae, and Rafflesiaceae. The second involves tissue specialization and early connection with host xylem, as exemplified by Santalaceae species. These differences are hypothesized to be related to the absence/presence of photosynthesis in these plants.

Host–Pathogen interaction under favorable environmental variables results in disease syndrome followed by symptom production. There are different symptoms produced by plant pathogenic fungi namely necrosis, hypertrophy and hyperplasia and also hypotrophy and hypoplasia. Identification of the fungal pathogen and their classification is an important aspect to be dealt. Most of the pathogenic fungi are either obligate parasites or biotrophs. Around 13 million of fungi have been estimated and of which only 1,40,000 fungal species have been identified world over. India has got a record of 29,000 fungal species. Since 1/3 of global fungal biodiversity occurs in India, hence there is need to discover the fungi occurring in different ecological niches and also on crop plants. Around 30,000 plant pathogenic fungi have been reported in the world and of which 5000–7000 pathogenic fungi might have occurred on various crop plants and forest plants in India. Early detection of plant pathogenic fungi and diseases diagnosis are the important components that help in disease management. Morpho-taxonomy and molecular tools are employed in the identification of the plant pathogenic fungi. Establishment of relevant disease forecasting systems and models are important for early prediction of the outbreak of plant diseases. In India agriculture forms the backbone for the country’s economy besides offering food security and nutritional security to the growing population. The aspects and prospects related to biodiversity, taxonomy and plant disease diagnostics of plant pathogenic fungi from India are discussed.

This study considers nutrient content of hydrophytic host populations (Impatiens capensis and Justicia americana) and their obligate holoparasite, Cuscuta gronovii. Comparisons of mineral content i...

Entomopathogenic nematodes (EPNs) are obligate parasites that infect a broad range of insect species. Host-seeking is a crucial step for EPN infection success and survival. Yet, the identity and ecological functions of chemicals involved in host-seeking by EPNs remain overlooked. In this review, we report known CO2, plant-derived and insect-derived cues shaping EPN host-seeking and recognition. Despite species-specific response to environmental cues, we highlight a hierarchical integration of chemicals by EPNs. We further emphasize the impact of EPN selection pressure, age, and experience on their responsiveness to infochemicals. Finally, we feature that EPN chemical ecology can translate into powerful sustainable strategies to control insect herbivores in agriculture.

The unicellular trypanosomatids belong to the phylum Euglenozoa and all known species are obligate parasites. Distinct lineages infect plants, invertebrates, and vertebrates, including humans. Genome data for marine diplonemids, together with freshwater euglenids and free-living kinetoplastids, the closest known nonparasitic relatives to trypanosomatids, recently became available. Robust phylogenetic reconstructions across Euglenozoa are now possible and place the results of parasite-focused studies into an evolutionary context. Here we discuss recent advances in identifying the factors shaping the evolution of Euglenozoa, focusing on ancestral features generally considered parasite-specific. Remarkably, most of these predate the transition(s) to parasitism, suggesting that the presence of certain preconditions makes a significant lifestyle change more likely.

Entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are obligate parasites of soil inhibiting insects. EPNs are being widely researched as promising biocontrol agents for a wide range of agricultural pests. It is known that strains of EPNs isolated from different geographical regions differ in their attributes, such as host-finding ability, host range, infectivity, reproduction, and environmental stress tolerance. A precise knowledge of these factors is therefore an essential pre-requisite for devising successful strategies to use these nematodes in biological control programmes. Thus, ecological characterisation of the EPN Heterorhabditis indica (Rhabditida: Heterorhabditidae) newly isolated and representing the only species of EPN reported from the island of Viti Levu, Fiji was carried out using Galleria mellonella larvae (L) (Pyralidae: Galleriinae) as hosts to allow comparisons between bioassays conducted in different laboratories around the world. Temperature data showed that native isolates of H. indica are warm-adapted nematodes with thermal range for infectivity between 15˚C and 35˚C and can reproduce between 20˚C and 30˚C. They are highly virulent with LC50 values against G. mellonella ranging from 2.8 IJ to 3.8 IJ/larva. However, they showed poor desiccation tolerance and fail to infect hosts in soil with moisture levels below 8%. They showed a moderate level of hypoxic tolerance and can be stored at 15˚C for 4 months. Results also showed great variability within the selected native isolates of H. indica. Beneficial traits for selected isolates were added up to identify a superior candidate. The current study also suggested that the thermal niche breadth for infection can differ among conspecific strains of an EPN species. The results of this experimental study on ecological aspects of these native isolates of H. indica should form a basis for their potential use in biological control of insect pests in Fiji.

Toxoplasma gondii is an intracellular parasite of the protozoan group and is obligate parasite with definitive host is a cat and other family felidae, Toxoplasma gondii can cause Toxoplasmosis and is categorized as one of zoonotic diseases. This study aims to determine the Toxoplasma gondii infection in domestic cats (Felis domesticus) in the traditional markets of Sawahan sub-district, Surabaya City. This study used a faecal sample of 46 domestic cats in the traditional markets of the Sawahan sub-district consisting of 20 female cats, 10 male cats, and 16 kittens. Then examined at the Laboratory of Parasitology, Faculty of Veterinary Medicine, Wijaya Kusuma University. The examination was carried out by the native method using eosin 2% and the floating method using saturated sugar and observed under a microscope with a magnification of 100x-400x. The results showed there were no cats infected with Toxoplasma gondii but found 3 endoparasites namely Ancylostoma sp 23.9%, Toxocara cati 41.3% and Isospora rivolta 4.3%.

Microsporidia are intracellular, obligate parasites. They have wide infection range from diverse phyla of invertebrates to vertebrates and also these eukaryotic pathogens parasitize those hosts which themselves are parasites, thus revealing hyperparasitism. The present study describe intracellular pathogen microsporidia which is isolated from a nematode parasite, Ascaridia sp. which itself is a parasite of fowl, Gallus gallus domesticus. The initial detection by optical microscopy represented numerous refractive oval spores in the homogenate samples of nematodes with mean spore length and width of 4.32±0.32μm×1.57±0.26μm (N=10). Giemsa staining exhibited demarcating stages of spore development. Spores developing in sporophorous vesicle, mature spores of considerable size and shape, dividing sporonts and sporoblasts, were clearly noticeable. However, the phases of proliferation (merogony) were indistinguishable. The ultrastructural study by Scanning electron microscopy illustrated intracellular development of microspor-idian spore inside nematode tissues. Xenoma formation as well as spore adherence to the epithelial wall most likely indicated the degradation and auto-infection by the microsporidian spores in the host tissue. A spore infecting host tissue by ejecting its polar tubule was also captured. Thus, the overall study focuses on developing microsporidia as hyperparasite in nematodes, although further classification for determining the genus has been left to be explored.

Toxoplasma gondii is an opportunistic obligate parasite, ubiquitous around the globe with seropositivity rates that range from 10% to 90% and infection by the parasite of pregnant women causes pre-...

Purpose Bacteria of the genus Bartonella are obligate parasites of vertebrates. Their distribution range covers almost the entire world, from the Americas to Europe and Asia. Many Bartonella species use rodents as reservoirs, and while much is known about Bartonella infection of rodents in central Europe, its extent is poorly understood in Eastern Europe. Methods The present study examines five rodent species (Apodemus flavicollis, Myodes glareolus, Microtus arvalis, Apodemus agrarius, Apodemus sylvaticus) in the Chernobyl Exclusion Zone in Ukraine. Total of 36 small mammals were captured in September 2017. Results The overall prevalence of Bartonella spp. was 38.9% (14/36) in rodents. Obtained four sequences from Apodemus flavicollis, were identical to Bartonella grahamii and B. taylorii. Conclusion This is the first report to confirm the presence of Bartonella spp. in rodents in the Chernobyl Exclusion Zone, Ukraine by molecular methods. The sequences show similarity to Bartonella strains occurring in Europe.

Introduction: The causative agent of toxoplasmosis is Toxoplasma gondii (T. gondii); an intracellular obligate parasite causes abortion in humans and animals. The review aims to clarify the situation of the disease in humans and animals in different parts of the country so that data will be available for any future work regarding the control of the disease. Methodology: All humans and animal research studies published in the last 18 years between 2000 and 2018 in Saudi Arabia were targeted, including prevalence or seroprevalence of T. gondii infection or antibodies. The searched strategy included human or pregnant women or children as well as animals or any particular species. Results: The result showed that approximately one-third of the population in Saudi Arabia had IgG seropositivity, and 6.4% had IgM seropositivity. Moreover, the disease was widespread in almost all the regions except AL- Jouf, where no data published. The prevalence of the chronic infection was high in sheep in Riyadh 68%, and the prevalence of acute was found in Najran 19% in sheep, goats, and camels. Conclusions: The current article showed the importance of the disease in Saudi Arabia for both humans and animals. The educational programs should be established to impart people to avoid the infection by the parasite.

Clubroot, a soil-borne disease caused by the obligate parasite Plasmodiophora brassicae Woronin, is a threat to canola (Brassica napus L.) production in western Canada. Genetic resistance represent...

The host:parasite interactions of the 3 serious haplosporidian pathogens of oysters, on which most information exists, are reviewed. They are Bonamia ostreae in Ostrea spp. and Crassostrea gigas; Bonamia exitiosa in Ostrea spp.; and Haplosporidium nelsoni in Crassostrea spp. Understanding the haemocytic response to pathogens is constrained by lack of information on haematopoiesis, haemocyte identity and development. Basal haplospridians in spot prawns are probably facultative parasites. H. nelsoni and a species infecting Haliotis iris in New Zealand (NZAP), which have large extracellular plasmodia that eject haplosporosomes or their contents, lyse surrounding cells and are essentially extracellular parasites. Bonamia spp. have small plasmodia that are phagocytosed, haplosporosomes are not ejected and they are intracellular obligate parasites. Phagocytosis by haemocytes is followed by formation of a parasitophorous vacuole, blocking of haemocyte lysosomal enzymes and the endolysosomal pathway. Reactive oxygen species (ROS) are blocked by antioxidants, and host cell apoptosis may occur. Unlike susceptible O. edulis, the destruction of B. ostreae by C. gigas may be due to higher haemolymph proteins, higher rates of granulocyte binding and phagocytosis, production of ROS, the presence of plasma β-glucosidase, antimicrobial peptides and higher levels of haemolymph and haemocyte enzymes. In B.exitiosa infection of Ostrea chilensis, cytoplasmic lipid bodies (LBs) containing lysosomal enzymes accumulate in host granulocytes and in B. exitiosa following phagocytosis. Their genesis and role in innate immunity and inflammation appears to be the same as in vertebrate granulocytes and macrophages, and other invertebrates. If so, they are probably the site of eicosanoid synthesis from arachidonic acid, and elevated numbers of LBs are probably indicative of haemocyte activation. It is probable that the molecular interaction, and role of LBs in the synthesis and storage of eicosanoids from arachidonic acid, is conserved in innate immunity in vertebrates and invertebrates. However, it seems likely that haplosporidians are more diverse than realized, and that there are many variations in host parasite interactions and life cycles.

Plants usually suffer from parasitic and non parasitic diseases in the world. One of the major groups that cause infections in plants belong to viruses, which is obligate parasite and replicate only in living cells. They are generally insect or seed transmitted and changes associated with global warming may affect both their incidence and severity. New virus diseases that are threatening the world’s agricultural production are called “emerging diseases” which are commonly detected on different crop plants. Recent emerging viruses have RNA or DNA genome and belong to Potyviridae, Bunyaviridae, Geminiviridae, Closteroviridae, Betaflexiviridae and Secoviridae families. Plant virus diseases, like diseases caused by other pathogens, appear to be proliferating at ever increasing rates. Scientific and popular media abound with terms such as new, emerging, re-emerging and threatening plant diseases. In the present paper, the emerging viral diseases reported in cotton were discussed in detail.

Rust fungi are obligate parasites, of plants, with complex and in many cases poorly known life cycles which may include host alteration and up to five spore types with haploid, diploid, and dikaryotic nuclear stages. This study supports that Thekopasora areolata, the causal agent of cherry‐spruce rust in Norway spruce, is a macrocyclic heteroecious fungus with all five spore stages which uses two host plants Prunus padus and Picea abies to complete its life cycle. High genotypic diversity without population structure was found, which suggests predominantly sexual reproduction, random mating and a high gene flow within and between the populations in Fennoscandia. There was no evidence for an autoecious life cycle resulting from aeciospore infection of pistillate cones that would explain the previously reported rust epidemics without the alternate host. However, within cones and scales identical multilocus genotypes were repeatedly sampled which can be explained by vegetative growth of the fertilized mycelia or repeated mating of mycelium by spermatia of the same genotype. The high genotypic diversity within cones and haplotype inference show that each pistillate cone is infected by several basidiospores. This study provides genetic evidence for high gene flow, sexual reproduction, and multiple infections of Norway spruce cone by the rust fungus T. areolata which expands the general understanding of the biology of rust fungi., The biology and epidemiology of obligate parasites and in particular rust fungi are poorly understood since they are notorious difficult to study. The life cycle of rust fungi includes host alteration and up to five spore types with haploid, diploid, and dikaryotic nuclear stages which complicates the analyses of them. In this manuscript we show several feature and particularities of the rust fungi Thekopsora areolata which recently become a serious threat to seed production in Norway spruce (Picea abies). In our study, we used newly develop microsatellite markers to analyze the population structure and epidemiology; the study answers important questions of T. areolata biology, its reproduction, infection biology, and mode of spread in host tissue.

The broomrapes are root, obligate parasites without chlorophyll. They parasitize mostly the dicotyledonous plants. Phelipanche ramosa (L.) Pomel attacks a wider range of hosts among which is the winter oilseed rape (Brassica napus L.). The broomrape can reduce the yields and aggravate the quality of production. There are few effective measures to control this parasite. One of the most promising approaches is the cultivation of Clearfield® oilseed rape and the treatment of imazamox-containing herbicide products. For this purpose during the growing seasons of 2016 - 2017 and 2017 - 2018 a field pot experiment with the Clearfield® oilseed rape hybrid РТ 228 CL was conducted. The soil of the field pots was artificially infested with Ph. ramosa seeds. The herbicide application was performed in two stages of the crop in the spring - BBCH 31–33 (1-3 internodes visible) and BBCH 51 („green button“). Variants of the trial were: 1. Untreated control; 2. Cleranda® (375 g/l metazachlor + 17,5 g/l imazamox) – 2,00 l/ha (BBCH 31–33); 3. Cleravo® (250 g/l quinmerac + 35 g/l imazamox) – 1,00 l/ha (BBCH 31–33); 4. Pulsar® Plus (25 g/l imazamox) – 1,00 l/ha (BBCH 31–33); 5. Pulsar® Plus – 2,00 l/ha (BBCH 31–33); 6. Pulsar® Plus – 0,50 l/ha (BBCH 51); 7. Pulsar® Plus – 1,00 l/ha (BBCH 51); 8. Pulsar® Plus – 2,00 l/ha (BBCH 51). Average for both years of the study, the highest efficacy against the parasite after the application of Pulsar® Plus – 2,00 l/ha (BBCH 51) – 92,9% followed by Cleranda® – 2,00 l/ha (BBCH 31–33) - 91,2% was reported.

Holocarpic oomycetes convert their entire cytoplasm into zoospores and thus do not form dedicated sporangia or hyphal compartments for asexual reproduction. The majority of holocarpic oomycetes are obligate parasites and parasitoids of a diverse suite of organisms, among them green and red algae, brown seaweeds, diatoms, fungi, oomycetes and invertebrates. Most of them are found among the early diverging oomycetes or the Peronosporomycetes, and some in the early-diverging Saprolegniomycetes (Leptomitales). The obligate parasitism renders it difficult to study some of these organisms. Only a few members of the genus Haliphthoros s. l. have been cultured without their hosts, and of the parasitoid Leptomitales, some transient cultures have been established, which are difficult to maintain. Here, the cultivation of a new holocarpic oomycete genus of the Leptomitales, Bolbea, is presented. Bolbea is parasitic to ostracods, is readily cultivable on malt extract agar, and upon contact with water converts its cytoplasm into zoospores. Its morphology and phylogenetic relationships are reported. Due to the ease of cultivation and the ready triggering of zoospore development, similar to some lagenidiaceous oomycetes, the species could be a promising model to study sporulation processes in detail.

Langsdorffia is a poorly known genus of flowering plants unlike any other in appearance, resembling deep sea creatures, rather more than they do flowering plants. The scarcity, elusive nature, and remote locations of these plants indicate that further species may await discovery. Furthermore, little is known about the biology of most of the species already known to science. Langsdorffia, like other parasitic plants, is poorly represented in botanic garden collections, and should be a candidate for further research and conservation focus.

Toxoplasma gondii is an obligate parasite and intracellular protozoans infect all kinds of animals and humans. The aim of the present study was to determine whether there was any effect on complete blood count parameters in the blood of pregnant women. A case-control study was performed in pregnant women divided into two groups according to their age: group one (17-27 years) and group two (28-45 years). A total of 130 pregnant women participated in the present study. A questionnaire was used to collect the data. IgG and IgM ELISAs were performed to detect antibodies against T. gondii and differentiate between acute and chronic diseases. The results showed a significant change in monocytes in the younger infected group (p

Dulosis is a type of social parasitism in which a parasitic ant has become dependent on captured workers (hosts) of a closely related species. Dulosis can be either facultative or obligate depending on the degree of dependence on host workers. As parasites become more specialized over evolutionary time, their domestic abilities degenerate until they become unable to survive without the host. However, depending on the degree of specialization, the “lost” behaviors may display some degree of recovery when host workers are unavailable to do the tasks. The 12 species of the Formica sanguinea group are all traditionally considered to be facultative parasites. However, recent studies suggest that one member of the group, F. subintegra, has characteristics that are more consistent with obligate parasitism. To explore the degree to which F. subintegra has become obligate, this study examined the degree of recovery of foraging and nest excavation behaviors of parasites when hosts are removed. When parasites were isolated from hosts, they spent more time foraging and feeding regurgitated food to nestmates (oral trophallaxis), and tended to begin feeding sooner following a period of fasting than when hosts were present. Isolated parasites were able to excavate suitable tunnels and engaged in nest building behavior significantly more often than parasites in groups with hosts. These results indicate that F. subintegra demonstrates some recovery of its foraging and nest excavation abilities, and can be considered a less specialized (more primitive) obligate parasite. Formica subintegra and its facultative relatives can be used as models for studying the progression of dulotic evolution within a closely related group of social parasites, and may shed light on which factors contribute to the transition from facultative to obligate parasitism.

How plant-associated microbiota are shaped by, and potentially contribute to, the unique ecology and heterotrophic life history of parasitic plants is relatively unknown. Here, we investigate the leaf and root bacterial communities of the root holoparasite Orobanche hederae and its host Hedera spp. from natural populations. Root bacteria inhabiting Orobanche were less diverse, had fewer co-associations, and displayed increased compositional similarity to leaf bacteria relative to Hedera. Overall, Orobanche bacteria exhibited significant congruency with Hedera root bacteria across sites, but not the surrounding soil. Infection had localized and systemic effects on Hedera bacteria, which included effects on the abundance of individual taxa and root network properties. Collectively, our results indicate that the parasitic plant microbiome is derived but distinct from the host plant microbiota, exhibits increased homogenization between shoot and root tissues, and displays far fewer co-associations among individual bacterial members. Host plant infection is accompanied by modest changes of associated microbiota at both local and systemic scales compared with uninfected individuals. Our results are a first step towards extending the growing insight into the assembly and function of the plant microbiome to include the ecologically unique but often overlooked guild of heterotrophic plants., The first in situ investigation of bacterial communities inhabiting parasitic plants and their hosts reveals simplification and homogenization of the parasite microbiota, but also influence from the host microbiota.

Most known species of entomopathogenic nematodes (EPNs) are generalist obligate parasites of insects. They kill their hosts within days after infection and mortality is mainly caused by toxins produced by bacteria that co-infect the hosts and serve as food for the nematodes. EPNs can infect a very broad spectrum of insects and these insects can therefore be expected to have evolved strategies to avoid infection. Indeed, ants are known to avoid feeding on EPN-infected insect cadavers, most likely because they are repelled by semiochemicals that emanate from the cadavers. The source and nature of these repellents are so far unknown. In a series of behavioral and chemical analytical experiments we identified hexadecanal and 2-heptadecanone as two compounds that are emitted by insect larva that are infected by the EPN Steinernema feltiae, but not by uninfected larvae. When spiking honey water with the two semiochemicals, they were confirmed to be highly deterrent to the ant Lasius niger. The environmentally benign hexadecanal and 2-heptadecanone could be employed to ward off ants and possibly other pests. Additional experiments are needed to fully determine their application potential., Open Access funding provided by Université de Neuchâtel. This work was supported by grant 31003A_166632 from the Swiss National Science Foundation.

Main conclusion Metabolites in Rafflesia-infected and non-infected Tetrastigma were compared which may have applications in Rafflesia propagation. Benzylisoquinoline alkaloids, here reported for the first time in Vitaceae, were abundant in non-infected shoots and may be a form of defense. In Rafflesia-infected shoots, oxylipins, which mediate immune response, were elevated. Abstract Endemic to the forests of Southeast Asia, Rafflesia (Rafflesiaceae) is a genus of holoparasitic plants producing the largest flowers in the world, yet completely dependent on its host, the tropical grape vine, Tetrastigma. Rafflesia species are threatened with extinction, making them an iconic symbol of plant conservation. Thus far, propagation has proved challenging, greatly decreasing efficacy of conservation efforts. This study compared the metabolites in the shoots of Rafflesia-infected and non-infected Tetrastigma loheri to examine how Rafflesia infection affects host metabolomics and elucidate the Rafflesia infection process. Results from LC–MS-based untargeted metabolomics analysis showed benzylisoquinoline alkaloids were naturally more abundant in non-infected shoots and are here reported for the first time in the genus Tetrastigma, and in the grape family, Vitaceae. These metabolites have been implicated in plant defense mechanisms and may prevent a Rafflesia infection. In Rafflesia-infected shoots, oxygenated fatty acids, or oxylipins, and a flavonoid, previously shown involved in plant immune response, were significantly elevated. This study provides a preliminary assessment of metabolites that differ between Rafflesia-infected and non-infected Tetrastigma hosts and may have applications in Rafflesia propagation to meet conservation goals.

Clubroot disease caused by the obligate parasite Plasmodiophora brassicae is a serious threat to cabbage production worldwide. Current clubroot control primarily relies on a fungicide, but this has a negative impact on the environment and the use of a single biocontrol agent cannot efficiently control the disease. Thus, the combined application of different biocontrol agents has been proposed as a promising alternative. In this study, we used bacterial biocontrol agents as a co-culture (inter-genus and intra-genus) and mono-culture to mitigate the clubroot disease of Chinese cabbage. We evaluated their biocontrol effect and plant growth promoter (PGP) traits in in vitro and in vivo experiments. This study revealed that the inter-genus bacterial co-culture significantly suppresses the incidence of clubroot disease and enhances plant growth compared with intra-genus and mono-culture. In pairwise interaction, we observed that Bacillus cereus BT-23 promotes the growth of Lysobacter antibioticus 13-6 (inter-genus bacterial co-culture), whereas L. capsici ZST1-2 and L. antibioticus 13-6 (intra-genus microbial co-culture) are antagonists to each other. Furthermore, a total of 5575 metabolites, 732 differentially expressed metabolites (DEMs), and 510 unique metabolites were detected through the LC-MS/MS technique in the bacterial co-culture. The number of unique metabolites in inter-genus bacterial co-culture (393 metabolites) was significantly higher than in the intra-genus bacterial co-culture (117 metabolites). Further analysis of DEMs showed that the DEMs were mainly involved in four kinds of metabolism pathways, i.e., carbohydrate metabolism, amino metabolism, nucleotide metabolism, and metabolism of cofactors and vitamins. The contents of some secondary metabolites with biocontrol activity and plant growth-promoting functions were increased in inter-genus bacterial co-culture, indicating that inter-genus bacterial co-culture has a solid potential to suppress clubroot disease. We conclude that the inter-genus bacterial interaction changes the community metabolism and improves several secondary metabolites functions with respect to disease control and PGP ability.

Echinopsis chiloensis is an endemic cactus from Chile, distributed in a temperature and rainfall gradient between 30° and 35° South latitude, with mean temperatures increasing and precipitation decreasing toward the north. It is the main host of the mistletoe Tristerix aphyllus, a holoparasite completely dependent on the cactus for water, carbon, and minerals. In this study, we investigated the consequences of parasitism over the fitness and physiology of this cactus throughout its distribution range and how it is affected by the environment. We measured five functional traits in eight populations latitudinally distributed, the first three only for the host: reproductive fitness, stomatal traits (density and size), and photosynthesis (during winter and summer); and the last two for the host and parasite: stable isotopes (∂13C and ∂15N), and nutrients (carbon and nitrogen content). The results showed a negative effect of parasitism over fitness of infected cacti. However, the higher nitrogen concentrations in cactus tissues toward the south improved overall fitness. Regarding photosynthesis, we only observed a negative effect of parasitism during the dry season (summer), which is also negatively affected by the increase in summer temperatures and decrease in winter rainfall toward the north. There were no differences in nutrient concentration or in the isotopic signature of healthy and infected cacti. Conversely, we observed a higher carbon and lower nitrogen concentration in mistletoes than in cacti regardless of latitude. The loss of temperature seasonality toward the north increases the C:N ratio, and the values between the parasite and its host diverge. ∂15N was similar between parasites and hosts while ∂13C of the parasite was enriched when compared to its host. Overall, the infection by T. aphyllus affects Echinopsis chiloensis fitness but showed no strong effects over the cactus physiology, except for the summer photosynthesis. Therefore, our data revealed that E. chiloensis response to T. aphyllus infection is sensitive to environmental changes in a way that could be strongly impacted by the desertification projected for this area due to climate change.

The abstract is available here: https://uscholar.univie.ac.at/o:1600630

В предлагаемой статье приводятся данные о двух новых для Казахстана видах почвенных зигомицетов, обнаруженных в ризосфере различных древесных растений на территории Заилийского и Кунгей Алатау (Северный Тянь-Шань) – Piptocephalis cylindrospora и Lichtheimia corymbifera. Вид P.cylindrospora является облигатным паразитом представителей зигомицетовых грибов, на территории исследований обнаружен дважды в Кунгей Алатау на видах Absidia spinosa и Lichtheimia corymbifera в ризосфере Populus tremula. Заметного ухудшения развития хозяина не вызывает. Ранее на территории Казахстана был зарегистрирован только Piptocephalis arrhiza в ризосфере Armeniaca vulgaris, Populus tremula, Picea schrenkiana и Juniperus spp. Вид Lichtheimia corymbifera, ранее относящийся к роду Absidia,отмечен в ризосфере Populus tremula в Кунгей Алатау и в ризосфере Picea schrenkiana, Salix sp. и Crataegus sp. в Заилийском Алатау. Для L. corymbifera характерны высоты 1677 м в Кунгей Алатау и от 1516 до 2007 м над ур. м. в Заилийском Алатау. До недавнего времени в Казахстане только близкородственный вид Absidia spinosa был выделен из ризосферы Malus sieversii, Armeniaca vulgaris, Crataegus spp., Pinus sylvestris, Populus spp., Sorbus tianschanica, Picea schrenkiana и Salix spp. Предлагаются описания колоний видов на основе выделенных чистых культур, морфологические данные, сведения об экологии и распространении. В культурах L. corymbifera наблюдается так называемый «самопаразитизм», при котором гифы гриба колонизируют спорангиеносцы, и последние выглядят пронизанными гифами. Половая стадия обоих видов в наших исследованиях не обнаружена., This article provides data on two species of soil zygomycetes, new to Kazakhstan, found in the rhizosphere of various woody plants in the Trans-Ili and Kungey Alatau (Northern Tien Shan) – Piptocephalis cylindrospora and Lichtheimia corymbifera. P. cylindrospora is an obligate parasite of zygomycetous fungi; in the study area, it was found twice in Kungey Alatau on species Absidia spinosa and Lichtheimia corymbifera in the rhizosphere of Populus tremula. It does not cause a noticeable deterioration in the development of the host. Earlier, in Kazakhstan, only Piptocephalis arrhiza was registered in the rhizosphere of Armeniaca vulgaris, Populus tremula, Picea schrenkiana, Juniperus spp. Lichtheimia corymbifera, previously belonging to the genus Absidia, was recorded in the rhizosphere of Populus tremula in Kungey Alatau and in the rhizosphere of Picea schrenkiana, Salix sp., Crataegus sp. in Trans-Ili Alatau. L. corymbifera is characterized by heights of 1677 m in Kungey Alatau, and from 1516 to 2007 m a. s. l. in Trans-Ili Alatau. Until recently, in Kazakhstan, only a closely related species Absidia spinosa was isolated from the rhizosphere of Malus sieversii, Armeniaca vulgaris, Crataegus spp., Pinus sylvestris, Populus spp., Sorbus tianschanica, Picea schrenkiana, Salix spp. Descriptions of species colonies based on isolated pure cultures, morphological data, information on ecology and distribution are offered. In L. corymbiferacultures, the so-called “self-parasitism” is observed, in which the fungal hyphae colonize sporangiophores, and the latter look like penetrated by hyphae. The sexual stage of both species was not found in our studies.