Field of Study – Biology (N 010)

Plant pathogens are among the most important components of the microbiome and have a major impact on both ecological and evolutionary processes in host plants. Phytopathogenic micro-organisms (bacteria, fungi) also cause significant economic losses in many parts of the world, with plant diseases accounting for up to 30% of the world’s crop yields, resulting in billions of dollars of losses each year. This has led to a particular focus on the interaction of pathogenic microorganisms with vulnerable plants. Recent research worldwide, including in Europe, is now mainly focused on the specific virulence factors that affect plant health. A better knowledge of the characteristics of pathogenic microorganisms, and an understanding of population structure and dynamics, may lead to the development of more effective control measures and more advanced and specific diagnostic protocols.
Research on plant pathogens causing plant diseases in Lithuania has been fragmented in recent years, with too few studies being conducted. However, they are important in epidemiological terms, as research would provide new information on the distribution of pathogens in Lithuania and, more broadly, in Europe. A better understanding of the structure and dynamics of pathogenic microorganism populations could lead to the development of more effective control measures and more advanced and specific diagnostic protocols. The aim of the research to be carried out is to use molecular biology techniques to identify and genetically characterise the pathogen(s) in host plants and to assess their virulence factors.
This work would contribute to the 2022–2026 scientific research and experimental development programme of the Nature Research Centre “Dispersion of harmful substances, pathogens and other stressors in a changing environment in the context of risk assessment and remediation (POLLUTION)”.

In recent decades, one of the biggest threats to forest ecosystems has been the extremely rapid spread of invasive organisms (pathogens, insects, etc.). Invasive species are moving into new territories and causing huge economic and ecological losses as a result of climate change and intensive international trade. One such invasive pathogen is the fungal microorganism Ophiostoma (Ascomycota), which causes Dutch Elm Disease (DED) in ash (Ulmus L.). Over the last 100 years, this disease has destroyed millions of ash trees worldwide. The studies have shown that hybridisation occurs between genes in O. novo-ulmi subspecies. Therefore, it is assumed that the pathogens have a high potential to form increasingly aggressive hybrids that displace less aggressive hybrids, as is the case with O. ulmi, which is no longer found in some countries, or is very rare and episodic.
According to recent studies in Lithuania, only one species of O. novo-ulmi has been identified so far, i.e. O. novo-ulmi ssp. novo-ulmi subspecies and the two-subspecies hybrid O. novo-ulmi ssp. novo-ulmi x ssp. americana. However, it is still unclear how they are formed, how and from where they spread (O. novo-ulmi ssp. americana has never been detected). Studies have also been published on differences in mycobiota between healthy and DED-damaged trees, but these have relied only on the occurrence of traits attributed to DED, without assessing which subspecies and/or hybrid is dominant, and whether this might also have influenced differences in mycobiota in damaged plants. Therefore, more detailed and extensive studies are needed, as this work is expected to compare the characteristics of pathogens found in the country. The PhD research would build knowledge on the epidemiology of the disease and the biological and ecological characteristics of the disease agent(-s). Molecular studies would investigate the properties of the pathogen populations, providing more information on population structure, hybridisation and other properties, as well as more information on the biology of the pathogen and possible routes of spread.

The genus Sarcocystis is worldwide distributed cyst-forming coccidian’s, with more than 200 species, commonly found in reptiles, birds, and mammals. Sarcocysts are formed in the muscles and CNS of intermediate hosts, and oocysts/sporocysts develops in the intestine of definitive hosts. Some species of Sarcocystis are pathogenic to humans, domestic and wild animals. Sarcocystis spp. are usually pathogenic to intermediate host. Prevalence, Sarcocystis species composition, definitive hosts, effects on intermediate host and hosts specificity is not well known in various animal species.

Dr. Petras Prakas is a world-renowned specialist in research on Sarcocystis parasites. He has published 45 publications on this topic (Clarivative Analytics in the “ISI Web of Science” database of the Scientific Information Institute), together with co-authors he described 15 new Sarcocystis species. In the implementation of research, cooperation with scientists from Spain, Latvia, Germany, the USA, Italy, Finland, Denmark, Switzerland, Argentina, Brazil, and the Czech Republic is conducted.

Sarcocystis species are described in intermediate hosts by combining morphological and molecular analysis methods. Mostly Sarcocystis spp. are examined in the muscles of intermediate hosts after the death of the animal. Meanwhile, the methods for identifying these parasites in the blood, intestines of final hosts, and faeces found in the environment are not sufficiently developed. Such studies using DNA analysis methods would help to identify the infection in the early phase and evaluate the role of different predators in the distribution of Sarcocystis parasites. In the context of food safety and biodiversity research, it is important to highlight the need for the development of Sarcocystis spp. diagnostic techniques.

By using nuclear DNA, mitochondrial DNA and apicoplast DNA markers it is expected to provide detailed genetic characterization of Sarcocystis species: S. glareoli and S. microti (previously assigned to the genus Frenkelia) forming cysts in the brain of small mammals. In muscle samples Sarcocystis species will be identified by pooled sample digestion and DNA analysis. Based on electron microscopy and molecular analysis of isolated sarcocysts it is expected to describe new Sarcocystis species. It will also be aimed to compare the species composition of the analysed parasites in small mammals caught in synanthropic environments in Lithuania and Spain and to create an effective methodology for the identification of parasites from blood samples.

The genus Sarcocystis is worldwide distributed cyst-forming coccidian’s, with more than 200 species, commonly found in reptiles, birds, and mammals. Sarcocysts are formed in the muscles and CNS of intermediate hosts, and oocysts/sporocysts develops in the intestine of definitive hosts. Some species of Sarcocystis are pathogenic to humans, domestic and wild animals. Sarcocystis spp. are usually pathogenic to intermediate host. Prevalence, Sarcocystis species composition, definitive hosts, effects on intermediate host and hosts specificity is not well known in various animal species.

Dr. Petras Prakas is a world-renowned specialist in research on Sarcocystis parasites. He has published 45 publications on this topic (Clarivative Analytics in the “ISI Web of Science” database of the Scientific Information Institute), together with co-authors he described 15 new Sarcocystis species. In the implementation of research, cooperation with scientists from Spain, Latvia, Germany, the USA, Italy, Finland, Denmark, Switzerland, Argentina, Brazil, and the Czech Republic is conducted.

Sarcocystis species are described in intermediate hosts by combining morphological and molecular analysis methods. Mostly Sarcocystis spp. are examined in the muscles of intermediate hosts after the death of the animal. Meanwhile, the methods for identifying these parasites in the blood, intestines of final hosts, and faeces found in the environment are not sufficiently developed. Such studies using DNA analysis methods would help to identify the infection in the early phase and evaluate the role of different predators in the distribution of Sarcocystis parasites. In the context of food safety and biodiversity research, it is important to highlight the need for the development of Sarcocystis spp. diagnostic techniques.

Faeces and small intestine samples of raccoon dogs, foxes, wolves, lynxes, dogs, and cats will be examined for the presence of Sarcocystis parasites. Since the oocysts and sporocysts produced by the final hosts are morphologically indistinguishable, DNA analysis methods (nested PCR, multiple PCR, species-specific PCR, quantitative PCR, sequencing, and analysis of the obtained DNA sequences) will be used for the identification of Sarcocystis species. It will be aimed to compare Sarcocystis species richness and infection rates in different predators, in natural and urban environments and in different European regions.

Apis mellifera are economically and ecologically important insects that ensure biodiversity in the natural environment and contribute to human welfare. Honey bees are well-known model organisms for microbiota research of insects living in natural environments. Honey bees microbial communities are important for the health of both individual bees and the entire hive. The intestinal microbiota of worker bees is fairly well studied, but the microorganism communities of different developmental stages honey bees (including drones) are almost completely unexplored.  Under unfavorable environmental conditions, changes in the composition of the honeybees-associated microbiota lead to an increase in the number of pathogenic microorganisms and viruses causing bee diseases. Antibacterial and antifungal therapy is applied to protect against pathogens; however, such a strategy changes the composition of bee microbiota and leads to the spread of multiple resistance to antibiotics. Therefore, it is appropriate to use natural microbiota components with biocontrol properties for the prevention of bee diseases. Searching for the latter microorganisms and evaluating their potential is relevant globally both in the context of increasing the health of honey bees and in the development of biocontrol tools. Due to the ever-increasing human population, there is a shortage of food in the world, so the idea of ​​using insects in the food industry is also growing up. Recently, due to the favorable composition of nutrients, there has been an interest in honey bee drone larvae as an alternative food source. However, the question of their microbiological contamination and safety, as well as their nutritional value and benefit to the consumer, remains particularly relevant.

The impact of factors caused by climate change on the functioning of Earth’s organisms and the state of ecosystems is currently a globally relevant topic. Climate change is believed to cause more frequent extreme events, including heavy rainfall, strong winds, heat waves and droughts, which can disrupt plant growth and make plants more vulnerable. Climate change studies show that many plants will be more stressed and less productive in the future. It is predicted that the yield of agricultural crops may decrease by several tens of percent during hot growing seasons. Therefore, studying the reaction of plants to changing conditions is important not only in a fundamental, but also in a practical sense.

Studies have shown that higher than normal temperatures lead to physiological and morphological changes in the plant. They accelerate the life cycle of plants, plants mature faster, so the intensity of photosynthesis changes and the yield decreases. As the competitive conditions of plants change under the influence of climate change, there is a need to strengthen the vital powers of agricultural plants. There is a lack of information on how stressful conditions will affect the physiological responses of plants and what environmentally friendly measures can be useful to reduce the harmful effects on the formation of reproductive organs.

Research will be conducted under natural field conditions and model conditions in the laboratory. Biostimulants will be used to search for means of controlling the processes that determine the productivity of agricultural plants. The effects of model climate change conditions and biostimulants on the functioning and productivity of economically useful plants will be assessed using physiological-biochemical and morphometric methods. Modeling the forecasted climate conditions will allow to study the possible impact on the sustainability of the resource and to search for measures to protect it.

Participation of the doctoral student in international scientific events, courses, and trainings is expected. The results of the work will be published at international scientific conferences and published in Clarivate Analytics Web of Science (CA WoS) referenced scientific journals.

Algae and cyanobacteria are characterized by a high diversity of bioactive compounds and have a great biotechnological potential for applications in the pharmaceutical, food, cosmetic industries, biofuel production, etc. Due to the increasing demand for natural, environmentally friendly, and safe biocomponent resources great attention is being paid to the research of algal and cyanobacterial metabolites, the search and screening of the target metabolites synthesising species and isolates. Most of the bioactive compounds are isolated from algal cultures or from the biomass of species grown in artificial systems. However, one of the main challenges to the production of bioproducts is the biosynthesis of specific metabolites under laboratory conditions and the high cost of cultivation of algal biomass in artificial systems. Meanwhile, excess algal biomass harvested from water bodies could provide a cheaper raw material.

The aim of the PhD studies is to assess the biotechnological potential of wild algal and cyanobacterial biomass as a renewable, sustainable natural resource. Structure of wild algal and cyanobacterial biomass, nutrients and other valuable biocomponents (pigments, lipids, phenolic compounds, cyanotoxins, etc.) in the biomass, biological activity of extracts will be analysed. The results will provide valuable information on the metabolic activity of aquatic organisms and their potential for use in biotechnology. They will contribute to the sustainable use of the country’s renewable bioresources and open up new opportunities to develop and expand the market for new bioproducts.

Herbicides are used both worldwide and in Lithuania to accelerate plant growth and increase competition with weeds. Weed competition is one of the most important biotic stress factors leading to a reduction in crop production. Herbicides have been found to cause abiotic stress to plants. Abiotic and biotic stresses of varying severity affect plant development, growth and ultimately productivity. Crop competition with unwanted plant species leads to lower yields, yet herbicides are considered to be the main effective tool for the control of unwanted weeds in modern crop production, helping to protect crop yields, economic profits and reducing competition between plants. The overall use of herbicides continues unabated worldwide, including in Lithuania. Thus, in order to avoid excessive use of herbicides, it is crucial to analyse the potential of using bioactive, environmentally friendly products to accelerate plant growth, to eliminate the adverse effects of herbicides on plants and, ultimately, to reduce the use of herbicides in agriculture. Plant probiotics may serve this purpose, but their potential for use has not yet been fully explored. The potential for their inclusion in plant biotechnology packages for crop production needs to be explored as part of the European Green Deal strategy, incorporating new technologies in the development of sustainable farming policies. In order to clarify the potential of probiotic preparations in eliminating herbicide-induced damage to plants, an analysis of biometric and biochemical parameters (stress level markers, enzymatic and non-enzymatic defence system and hormonal system) will be performed.