What influences the composition of fungi in wheat grains?

Wheat grains are inhabited by different fungi, including plant pathogens and fungi – mycotoxin producers. The composition of seed mycobiota can be influenced by different factors, including agronomic practices, but the results are still contradictory. The aim of this study was to evaluate the mycobiota of wheat grains depending on agroecological conditions. Wheat grains were obtained from a two-factorial field trial: A – tillage system (A1 – ploughing at a depth of 22–24 cm; A2 – harrowing at a depth of up to 10 cm); B – crop rotation (B1 – continuous wheat; B2 – oilseed rape and wheat; B3 – crop rotation). The mycobiota of grain were determined by mycological and molecular methods. The most abundant and widespread of the mycobiota were Pyrenophora tritici-repentis, Alternaria spp., Arthrinium spp., and Fusarium avenaceum. Higher amounts of precipitation increased the infection of grains with Fusarium fungi. Seven species of Fusarium were identified in the grain samples: F. avenaceum, F. poae, F. graminearum, F. culmorum, F. acuminatum, F. sporotrichioides, and F. tricinctum. The soil tillage method and crop rotation did not influence the total incidence of Fusarium spp., but the abundance of a particular species differed depending on agronomic practice. The research suggests that continuous wheat sowing under conditions of reduced soil tillage can increase the level of risk of grain infection with F. graminearum and, consequently, the accumulation of mycotoxins

Melanocortin receptor accessory protein effects on melanocortin receptor functional activation following stimulation with adrenocorticotropic hormone

Melanokortīnu receptora palīgproteīns (MRAP) ir nepieciešams, lai veidotos funkcionāls MC2R, taču tā ietekme uz pārējo melanokortīnu receptoru (MCR) spēju saistīt dažādus melanokortīnus vēl nav pilnībā izpētīta. Šī darba mērķis ir noteikt MRAPβ koekspresijas ietekmi uz MCR funkcionālo aktivitāti, stimulējot tos ar ACTH un α-MSH. Lai to sasniegtu tika veikta visu MCR ekspresija ar un bez MRAPβ cilvēka HEK293 šūnu līnijā, kam sekoja šūnu saražotā cAMP daudzuma izmaiņu noteikšana pēc to stimulācijas ar α-MSH un ACTH (1-24). Rezultāti pierāda, ka koekspressija ar MRAPβ palielina MCR funkcionālo atbildi pēc stimulācijas ar ACTH, savukārt pazemina - pēc stimulācijas ar α-MSH, kas norāda, ka MRAPβ loma organismā varētu būt nozīmīgāka par MC2R palīgproteīna lomu. Darbs veikts no 2012.gada oktobra līdz 2013. gada maijam Latvijas Biomedicīnas pētījumu un studiju centrā. Atslēgas vārdi: melanokortīna receptori, MRAPβ, ACTH, α MSH, cAMPMelanocortin receptor accessory protein (MRAP) is required to form a functional MC2R, but its impact on the rest of the melanocortin receptor's (MCR) ability to bind melanocortin peptides has not yet been fully explored. The aim of this work is to identify MRAPβ coexpression impact on MCR functional activity by stimulating them with ACTH and α-MSH. In order to achieve this was performed the MCR expression with and without MRAPβ in human HEK293 cell line, followed by cellular cAMP production volume changes associated with the stimulation of the α-MSH and ACTH (1-24). The results show that the MRAPβ coexpression increases MCR functional response after stimulation with ACTH, but decreases - after stimulation with α-MSH, indicating that MRAPβ role in the body may play a more important then just accessory protein role for MC2R. This work was carried out in Biomedical Research and Study Centre of Latvia during period from October 2012 to May 2013. Keywords: MCR, MRAPβ, ACTH, α-MSH, cAM

Melanocortin 2 receptor and its accessory protein production in yeast Pichia Pastoris expression system

Darba ietvaros tika izveidots pPIC9K- MC2R-T4L ekspresijas konstrukts, kas tika ekspresēts P.Pastoris sistēmā. Western blot analīze uzrādīja nepieciešamās molekulmasas zonu. MC2R-T4L izdevās attīrīt uz His- un Ha-tag afinitātes kolonnām. Lai noteiktu funkcionāla MC2R struktūru, to nepiecieciešams ekspresēt kompleksā ar MRAP, tādēļ tika izveidoti vairāki MC2-MRAP konstrukti, ko tālāk izmantot proteīna ekspresijai P. Pastoris šūnās. To aktivitāte tika pārbaudīta zīdītāju šūnu līnijās nosakot cAMP daudzuma izmaiņas pēc stimulācijas ar ACTH (1-24). Iegūtie rezultāti bija nestabili, tādēļ tālākajos pētījumos tiks veikta radioaktīvā ACTH saistīšanas mērījumus. Darbs tika veikts no 2013.gada jūnija līdz 2015. gada jūnijam Latvijas Biomedicīnas pētījumu un studiju centrā.During the course of the work pPIC9K- MC2R-T4L construct was created and used for protein production in yeast P.Pastoris expression system. Western blot analysis displayed presence of protein band with according molecular weight. Protein was purified using His- and Ha-tag affinity columns. MC2R can be activated only when coexpressed with MRAP. For this reason we created several MC2-MRAP constructs, which shall be further used for protein expression in P.Pastoris. Activity of the complex was evaluated in mammalian cell lines, by estimation of cAMP response upon stimulation with ACTH(1-24). Acquired results were not reproducible, thus it was decided to conduct radioactive ACTH binding measurements. Work was carried out from June 2013 to June 2015 in Latvian Biomedical Research and Study Centre

The Diversity of Fungi Involved in Damage to Japanese Quince

In recent years, Japanese quince (Chaenomeles japonica) plantations in Latvia have increased. Interest in breeding Japanese quince is also known in other European countries and Russia. The occurrence and harmfulness of fungal diseases have become increasingly significant. However, there is a lack of overall information in the literature about the diversity of fungi afflicting C. japonica. In our study, we aimed to determine the diversity of fungi associated with C. japonica in Latvia, with the possibility of identifying the fungi that are most characteristically associated with certain parts of the plant. Our research was conducted from 2017 to 2019 in eight Japanese quince plantations in Latvia. Samples of plant parts with disease symptoms were collected. Pure cultures of fungi were obtained and identified using ITS region sequencing. We determined the relative density of identified genera of fungi, which were grouped using hierarchical cluster analysis depending on the plant part from which they were found. Various disease-like symptoms were observed and described. A total of 538 isolates of fungi were obtained that belong to 36 genera and represent different ecological niches. Fusarium, Alternaria, Botrytis, and Sarocladium were the genera most frequently found during our study. The number of identified cases of fungal genera differed depending on the part of the plant from which the fungi were obtained. However, it is not possible to relate a specific genus of fungus to only one certain part of a plant. Further research is needed to clarify the pathogenicity of detected fungi and the composition of species in the detected genera of fungi

Botrytis four species are associated with chocolate spot disease of faba bean in Latvia

Faba bean (Vicia faba L.) is gaining importance as a crop in northern Europe. In this region, the most important disease of faba bean is chocolate spot disease, attributed to the pathogen Botrytis fabae. However, other Botrytis species have been found to contribute to the disease. Hence, it was decided to isolate fungi from faba bean plants showing symptoms of chocolate spot disease in Latvia, identify the Botrytis species using the DNA sequences of three definitive genes, evaluate the morphological diversity of the isolates in vitro and, finally, to determine the pathogenicity of the isolates in a detached-leaf test. In addition to B. fabae, B. cinerea, B. pseudocinerea and B. fabiopsis were all identified. Phylogenetic analysis of the DNA sequences put all the obtained 44 isolates unequivocally into clusters with known examples of each species. Every species showed wide diversity in its in vitro colour, texture and growing pattern of mycelium, production of sclerotia and pigmentation of the growing medium with much overlap between species showing that this method is not adequate for species discrimination. B. fabae produced the largest lesions on infected leaves, followed closely by B. pseudocinerea and B. cinerea, while B. fabiopsis produced much smaller lesions. The results show that chocolate spot disease of faba bean is attributable to Botrytis four species in northern Europe. This knowledge needs to be considered when controlling the disease by genetic or agronomic means.Peer reviewe

DIVERSITY OF FUNGI ASSOCIATED WITH WHEAT STEM BASE DISEASES

Wheat stem base diseases can be caused by different pathogens – previous research has showed complex infections. Also, fungi from other ecological niches can be associated with wheat stem base. Wheat stems with disease symptoms were collected in a field experiment where agronomic practices (different soil tillage systems under various crop rotation schemes) were evaluated from 2012 to 2020. Causal agents and other fungi associated with stem bases were identified by mycological and molecular genetic methods to genera/species level. A high diversity of fungi associated with stem base diseases was determined – fungi from 30 different genera were found. Altogether, 48% of identified fungi belonged to typical causal agents of stem base diseases, 15% were pathogens of wheat leaves and ears, and 37% were saprotrophs or fungi with unclear ecological guilds. Most often, stem base diseases were caused by Oculimacula spp., Fusarium culmorum, and F. avenaceum. Other pathogens (Rhizoctonia spp., Pythium spp., other species of Fusarium, etc.) were found only in some cases. Important pathogens of wheat – Pyrenophora tritici-repentis and Parastagonospora nodorum – were determined frequently. The spectrum of pathogens differed depending on the meteorological conditions of the vegetation period. Further research is required to clarify the relationships between different fungi and their influence on wheat development

Variations in the Relative Abundance of Gut Bacteria Correlate with Lipid Profiles in Healthy Adults

The gut microbiome is a versatile system regulating numerous aspects of host metabolism. Among other traits, variations in the composition of gut microbial communities are related to blood lipid patterns and hyperlipidaemia, yet inconsistent association patterns exist. This study aims to assess the relationships between the composition of the gut microbiome and variations in lipid profiles among healthy adults. This study used data and samples from 23 adult participants of a previously conducted dietary intervention study. Circulating lipid measurements and whole-metagenome sequences of the gut microbiome were derived from 180 blood and faecal samples collected from eight visits distributed across an 11-week study. Lipid-related variables explained approximately 4.5% of the variation in gut microbiome compositions, with higher effects observed for total cholesterol and high-density lipoproteins. Species from the genera Odoribacter, Anaerostipes, and Parabacteroides correlated with increased serum lipid levels, whereas probiotic species like Akkermansia muciniphila were more abundant among participants with healthier blood lipid profiles. An inverse correlation with serum cholesterol was also observed for Massilistercora timonensis, a player in regulating lipid turnover. The observed correlation patterns add to the growing evidence supporting the role of the gut microbiome as an essential regulator of host lipid metabolism

Epiphytic and Endophytic Fungi Colonizing Seeds of Two <i>Poaceae</i> Weed Species and <i>Fusarium</i> spp. Seed Degradation Potential In Vitro

Fungi colonizing the surface and endosphere of two widespread Poaceae weed species, Avena fatua and Echinochloa crus-galli, were isolated to compare the taxonomic composition between the plant species, location, and year of the seed collection. The seed-degrading potential of Fusarium isolated from the seeds was tested by inoculating seeds of E. crus-galli with spore suspension. Molecular identification of epiphytic and endophytic fungal genera was performed by sequencing the ITS region of rDNA. Endophytes comprised of significantly lower fungal richness compared to epiphytes. A significant taxonomic overlap was observed between the endosphere and seed surface. The most abundant genera were Alternaria, Fusarium, Cladosporium, and Sarocladium. Analysis of similarities and hierarchical clustering showed that microbial communities were more dissimilar between the two plant species than between the years. Fusarium isolates with a high potential to infect and degrade E. crus-galli seeds in laboratory conditions belong to F. sporotrichioides and F. culmorum

Evaluation of pathogenicity of Botrytis species isolated from different legumes

Fungi of genus Botrytis are important pathogens of legumes, causing gray mold and chocolate spot diseases. The use of molecular methods to identify pathogens has resulted in the discovery of several new Botrytis species and new associations of pathogens with diseases. Thus, chocolate spot of faba bean is now associated with at least four species: B. fabae, B. cinerea, B. pseudocinerea and B. fabiopsis. Species of Botrytis differ in host plant, pathogenicity, fungicide resistance and other relevant properties that affect disease control. The aim of this study was to identify the species of Botrytis isolated from different legume crops and to evaluate their in vitro pathogenicity. Between 2014 and 2019, 278 isolates of Botrytis were obtained from infected legumes in Latvia. A phylogenetic analysis was carried out by sequencing three nuclear genes, RPB2, HSP60, and G3PDH, considered to be diagnostic for species in this genus. A set of 21 representative isolates was selected for pathogenicity tests on detached leaves of faba bean, field pea, lupin and soybean using 5-mm mycelium-agar plugs. The diameter of the formed lesions under the inoculated plug was measured crosswise each day. The datasets were subjected to analysis of variance with the split-plot design of the experiment and repeated-measures model. Six species were identified: B. cinerea, B. fabae, B. pseudocinerea, B. fabiopsis, B. euroamericana and B. medusae. In addition to the expected combinations of host and pathogen, naturally occurring infections of B. fabiopsis were found on chickpea, B. euroamericana on faba bean and B. medusae in lupin seeds. Species and isolate had significant effects on pathogenicity on all crops tested. Several isolates were pathogenic on two or more host species: two of B. pseudocinerea, two of B. cinerea, two of B. fabiopsis and the one of B. medusae. One isolate of B. pseudocinerea and two of B. fabiopsis caused primary lesions on all five host species. The results show that these Botrytis species have a broad host range that should be borne in mind when planning crop sequences and rotations.Peer reviewe