Invasive species, especially plant pathogens, have a potential to completely eradicate native plant species and remodel landscapes. Tripartite interactions among sweet chestnut (Castanea sativa), chestnut blight-causing invasive fungus Cryphonectria parasitica, and hyperparasitic virus Cryphonectria hypovirus 1 (CHV1) were studied in two populations. The number of different vegetative compatibility (vc) types of C. parasitica more than doubled over the 10 years, while the hypovirulence incidence dropped in one population and slightly increased in the other one. Over the course of our 3-year monitoring experiment, the prevalence of hypovirulent isolates obtained from monitored cankers increased slowly (i.e., more hypovirulent isolates were being obtained from the same cankers over time). Within studied cankers, considerable changes in vc type and CHV1 presence were observed, indicating a highly dynamic system in which virulent and hypovirulent mycelia, sometimes of discordant vc types, often appeared together. The increase in hypovirulence prevalence did not have any observable curative effect on the cankers and, occasionally, reactivation of healed cankers by new, virulent C. parasitica isolates was observed. Both short- and long-term observations and revalidation of the infected plant populations are necessary to accurately estimate disease progress and formulate an adequate disease management strategy.

Chestnut blight has spread throughout Europe since the introduction of its causal agent, Cryphonectria parasitica, >70 years ago. In our study, we analyzed the diversity of vegetative compatibility (vc) and microsatellite genotypes of C. parasitica, as well as sequence diversity of Cryphonectria hypovirus 1 (CHV1) in six populations from Switzerland, Croatia, and North Macedonia. Resampling of local populations that were already investigated more than a decade ago allowed us to analyze the spatial and temporal population structure across an invasive range of the pathogen in Europe. Regardless of which genetic marker was used, the >60-year-old Swiss and Croatian populations had high population diversity, whereas more recent North Macedonian populations were mostly clonal. These diversity differences between the investigated populations remained stable over time. A high diversity of CHV1 was observed in all three countries, with North Macedonian strains forming a separate cluster from strains obtained in other countries. No correlation between vc diversity and CHV1 prevalence was observed, suggesting a well-established and maintained natural hypovirulence in all countries, further corroborated by an observed increase in genetic diversity of Croatian C. parasitica populations over time, without collapse of CHV1 prevalence.

The Republic of Croatia is spread in geographical and climatic conditions that support a great diversity of habitats and associated plant taxa, many of which can be used for food or medicine. However, urbanization, loss of natural habitats, as well as changes in people’s dependence on the natural resources from the surrounding environment may lead to the loss of valuable knowledge about the use of plants and mushrooms. With the aim of studying and preserving this knowledge in the continental north-western part of Croatia, an ethnobotanical survey was undertaken at the two study areas—Valpovo and Đurđevac, which included a total of 17 settlements. A total of 103 informants, 65% female and 35% male, aged between 22 and 83 years, participated in an interview using pre-planned questionnaires. The informants reported 131 plants belonging to 55 families and 17 mushroom taxa. The largest number of plants belonged to the families of Rosaceae, Lamiaceae, Asteraceae, and Apiaceae. In both areas, the informants cultivate and also gather wild plants, but these practices are better preserved in the area of Đurđevac where 109 taxa from 47 families were recorded. In addition to cultivated and gathered plants, informants from the Valpovo area also reported the use of purchased plants. Plants and mushrooms are mostly used as food (21 plant taxa and 17 mushrooms), but plants also serve as medicine (68 taxa), as both food and medicine (35 taxa), feed for cattle (11 taxa), repellent (four taxa), and/or space freshener (two taxa). The most frequently used wild plants are Chamomilla recutita, Mentha x piperita, and Urtica dioica, while Boletus edulis, Agaricus campestris, and Macrolepiota procera are the most often used mushrooms. The results indicate that the local people in the studied north-western part of Croatia still nurture the practice of cultivating and gathering plants and that herbal remedies are considerably important among the informants. The study should be further extended to broaden and preserve valuable ethnobotanical knowledge and encourage the protection of culturally important plants of the studied area.

In this study, we evaluated the leaf antioxidative responses of three wheat varieties (Srpanjka, Divana, and Simonida) treated with two different forms of zinc (Zn), Zn-sulfate and Zn-EDTA, in concentrations commonly used in agronomic biofortification. Zn concentration was significantly higher in the flag leaves of all three wheat varieties treated with Zn-EDTA compared to control and leaves treated with Zn-sulfate. Both forms of Zn increased malondialdehyde level and total phenolics content in varieties Srpanjka and Divana. Total glutathione content was not affected after the Zn treatment. Zn-sulfate increased the activities of glutathione reductase (GR) and guaiacol peroxidase (GPOD) in both Srpanjka and Divana, while glutathione S-transferase (GST) was only induced in var. Srpanjka. Chelate form of Zn increased the activities of GST and GPOD in both Simonida and Divana. Catalase activity was shown to be less sensitive to Zn treatment and was only induced in var. Srpanjka treated with Zn-EDTA where GPOD activity was not induced. Concentrations of Zn used for agronomic biofortification can induce oxidative stress in wheat leaves. The antioxidative status of wheat leaves could be a good indicator of Zn tolerance, whereas wheat genotype and chemical form of Zn are the most critical factors influencing Zn toxicity.

Dutch elm disease (DED) was originally caused by the ascomycete Ophiostoma ulmi, which has been replaced by a more virulent species, O. novo-ulmi, divided into subsp. novo-ulmi and subsp. americana. Permeable reproductive barriers, a period of co-occurrence of O. ulmi and O. novo-ulmi, and the current overlap of O. novo-ulmi subspecies have been important in shaping the present O. novo-ulmi populations in Europe, which were initially clonal, predominantly of the MAT-2 type. This study confirmed the persistence of O. novo-ulmi in Croatia over the years, although at some forest sites, the diseased elms were not detected. The methodology used to assess changes in O. novo-ulmi populations was based on the col1 and cu genes, which have subspecies-specific nucleotide differences, analysis of MAT idiomorphs, and temperature-growth responses. The col1 and cu gene sequencing did not reveal a change in the number of isolates with the recombinant col1/cu genotype over 10 years (2012–2022). At both sampling times, approximately one-fourth of all analyzed isolates had recombinant col1/cu genotypes. However, the frequency of MAT-1 isolates, which all have MAT-1 genes originating from O. ulmi, increased during this period. Differences in growth rate at 20, 26, and 30 °C revealed variations in the temperature response of isolates, which were affected by sampling time and mating type. The MAT-1 isolates were shown to grow more slowly than MAT-2 at the three temperatures tested. The advantage of MAT-2 was reflected in temporal differences in growth rate at resampled sites, particularly at lower temperatures. These results suggest that changes in the frequency of mating types in Croatia occurred between 2012 and 2022, accompanied by modifications in the pathogen’s response to temperature at the population level.

Knowledge related to the use of plants and mushrooms in the Baranja region of Croatia was documented through semi-structured interviews of 105 informants in 12 villages. We found 117 plant species and 7 mushrooms with medicinal uses. Rosaceae, Lamiaceae, and Asteraceae were the families with the most species, while Sambucus nigra, Chamomilla recutita, and Taraxacum officinale were the most frequently mentioned species. Leaves, fruits, and flowers were the most commonly used plant parts, predominantly prepared as infusions, syrups, and tinctures. Plants were mainly used to treat digestive and respiratory ailments, with the highest informant consensus recorded for ear, eye, and respiratory disorders. The results emphasize the persistence of rich ethnobotanical knowledge in the study area and highlight the importance of preserving this cultural and biological heritage for future generations.