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 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.

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.

Sarcocystis are obligate parasites characterized by a mandatory two-host life cycle. They form sarcocysts in various tissues of the intermediate host, often causing various severe and even lethal disorders. In nature, they are spread by definitive hosts – predators, omnivores, or scavenging animals. In them, the parasite develops in the intestine, forming sporocysts.

Agriculture suffers losses due to infections in domestic animals. Although typical Sarcocystis species in pigs, cows, sheep, etc., are intensively studied, in our practice, infections are often found under the microscope, but cannot be confirmed by molecular methods for typical species. This indicates the infection of these animals with other, atypical, or even new, unidentified species. Studies on Sarcocystis in cattle raised in Lithuania are described in only two publications, and their species diversity is not explored. Every year, the number of newly identified Sarcocystis species increases. Currently, it is known that cattle can serve as intermediate hosts for at least seven species, which have not been investigated in previous studies. The species diversity of Sarcocystis in pigs in Lithuania has also not been studied.

Humans can serve as definitive hosts for at least three species (S. hominis, S. heydorni, S. suihominis), whose intermediate hosts are pigs and cattle. Cases of poisoning by consuming atypical meat, such as horse meat, are also known. Infection can occur through improperly processed meat. To date, globally (Argentina, Iran, USA), only three articles have been published on Sarcocystis contamination in processed meat (canned beef, hamburgers, sausages, and hot dogs). There are no similar scientific publications in Lithuania or Europe.

The goal of the doctoral research is to investigate the species diversity of Sarcocystis in raw meat from farmed animals and in non-thermally processed meat products.

Viruses are noncellular forms of life infecting all known cellular organisms, among them are honey bees, which play a crucial role in maintaining biodiversity by pollinating various plants. Bee viruses can infect other insects as well and spread in various ways – the role of plants in the spreading of insect viruses is not yet well established. During this work, using modern molecular biology, microbiology, and metagenomic methods the viruses distributed on honey bee-pollinated plants and bees will be evaluated; an attempt will be made to establish the role of plants in their spreading among insects. Lately, various ecologically and human-friendly alternative antimicrobial agents are being researched. Of these, plant-based compounds and extracts, e.g. essential oils, are in focus. Their antiviral mode of action is not yet very well understood. In this work, by using yeast RNA viruses and other model systems the antiviral activity and action mechanisms of plant extracts and their constituents will be investigated. By analyzing the data on viral spread in bees and plants and the antiviral activity of plant-based substances, an assessment of the importance of plants in the transmission of viruses and the prevention of viral diseases will be made.

Muscular tissues of Lithuanian canids, mustelids, raccoons, felines, and birds of prey are planned to be examined for these parasites. The mammals and birds of prey will be collected in collaboration with the Tado Ivanauskas Museum of Zoology, the national authority responsible for monitoring dead and injured wild animals. Artificial digestion and microscopic methods will be used to detect parasites in muscles of hosts. Histopathological tests will be used to determine pathogenicity. Different PCR variants, sequencing and bioinformatic analysis of the DNA sequences obtained will be used for species identification. Statistical analysis of the data will be carried out using the SPSS package. The objectives of the study will be: 1) to identify the composition of parasites in predator muscle; 2) to determine the transmission potential of parasitic zoonoses and potential hosts; 3) to assess the level of pathogenicity of Sarcocystis parasites; 4) to evaluate the intra- and inter-species variability of the parasites studied by means of DNA sequence analysis.