Anthropogenic biodiversity decline threatens the functioning of ecosystems and the many benefits they provide to humanity¹. As well as causing species losses in directly affected locations, human influence might also reduce biodiversity in relatively unmodified vegetation if far-reaching anthropogenic effects trigger local extinctions and hinder recolonization. Here we show that local plant diversity is globally negatively related to the level of anthropogenic activity in the surrounding region. Impoverishment of natural vegetation was evident only when we considered community completeness: the proportion of all suitable species in the region that are present at a site. To estimate community completeness, we compared the number of recorded species with the dark diversity-ecologically suitable species that are absent from a site but present in the surrounding region². In the sampled regions with a minimal human footprint index, an average of 35% of suitable plant species were present locally, compared with less than 20% in highly affected regions. Besides having the potential to uncover overlooked threats to biodiversity, dark diversity also provides guidance for nature conservation. Species in the dark diversity remain regionally present, and their local populations might be restored through measures that improve connectivity between natural vegetation fragments and reduce threats to population persistence.

Cuscuta species (dodders) are parasitic plants that harm both native and cultivated flora, presenting significant ecological and economic challenges. This study employs random amplified polymorphic DNA (RAPD) markers to evaluate genetic variation among 70 specimens collected from various localities across Bulgaria. The findings reveal notable differences in RAPD profiles between species, indicating that RAPD markers are effective for species identification, particularly when reproductive organs are absent. While C. campestris exhibited a relatively uniform genetic profile across different populations, native species showed greater genetic heterogeneity, likely due to their development in diverse habitats. Geographical patterns were also observed in the genetic clustering of C. campestris, although seed dispersal mechanisms appeared to play a larger role in shaping genetic diversity than geographic distribution alone. This research highlights the potential of RAPD markers for improving species identification and for understanding the genetic dynamics of Cuscuta populations, which is crucial for managing their spread and minimizing their agricultural impact.

Dodders (Cuscuta spp.) are prominent parasitic plants widely known and exploited in traditional medicine. They are rich in polyphenolics, which determine their strong antioxidant potential. However, comparatively few of the nearly 200 known species have been characterized for their medicinal potential. In the present study, we aimed to explore the antioxidant potential of four of the most widely distributed Cuscuta species in Bulgaria—C. campestris, C. monogyna, C. epithymum, and C. europaea. They differed significantly in polyphenolic content and accordingly differed in their antioxidant properties, although this correlation is not always straightforward, as shown in C. europaeae. Furthermore, we evaluated the host plant species’ influence on the polyphenolic content, antioxidant properties, and flavonoid profile of C. campestris, finding a significant enhancement when the parasite was grown on aromatic plants—rosemary and thyme—compared to a model host—Arabidopsis thaliana. Seven major flavonoids and phenolic acids—chlorogenic acid, kaempferol-3,7-O-diglucoside, quercetin-3-O-galactoside, kaempferol-3-O-galactoside, quercetin-3-O-glucoside, astragalin, and isorhamnetin-7-glucoside—were annotated after HPLC-MS analysis and found to be affected by the host species. In conclusion, it was found that extracts from different Cuscuta species differ in their antioxidant potential, which the host plants might further modify.

Holoparasitic plants of the genus Cuscuta are generally considered prominent agricultural pests. In addition to their negative economic effect on agriculture and their impact on natural plant societies, they have also been long known in East Asian as medicinal plants with beneficial properties. This underlines the fact that Cuscuta spp. are particularly rich in specialized metabolites, flavonoids, alkaloids, and cumarines, among others. In addition to several well-characterized species, most of the species variety within the genus remains largely unstudied. In the present study we aimed to compare the flavonoid profiles of natural populations of two of the most abundant Cuscuta species in Bulgaria—the native C. epithymum, and the naturalized C. campestris. Based on HPLC-MS/MS analysis, a total of 13 polyphenolics compounds were annotated, with hyperoside and isoquercitrin being some of the most abundant. Some notable differences were found, like the complete absence of dicaffeoylquinic acid in C. campestris, and kaempferol-3,7-O-diglucoside and kaempferol 3-O-β-(6′′-O-trans-p-coumaroyl)-glucopyranoside in C. epithymum. The population of the two species clustered separately from each other, with some variations, but with no clear pattern of dependence on the locality or host species. Based on the results it can be concluded that flavonoids may be used as chemotaxonomical markers within the genus, showing that even in different climatic conditions and different host ranges, the two studied species clearly differed from each other. Also, their rich content emphasizes the potential of these parasites as a source of bioactive compounds.

Plants are continuously subjected to the unfavorable impact of abiotic stress factors, of which soil salinity is among the most adverse. Although away from direct soil contact throughout most of their lifecycle, stem parasitic plants of the genus Cuscuta, family Convolvulaceae are also affected by salinity. The present study aimed to assess salt stress impact on germination and early establishment of three Cuscuta species, in comparison to related nonparasitic vines of the same family. It was found, that Cuscuta spp. are highly sensitive to NaCl concentration within the range of 200 mM. Germination was delayed in time and reduced by nearly 70%, accompanied by decrease in further seedling growth, ability to infect host plants and growth rate of established parasites. The nonparasitic vines showed similar sensitivity to salinity at germination level, but appeared to adapt better after the stress factor was removed. However, the negative effect of salinity did not fully prevent some of the Cuscuta species from infecting hosts, probably a beneficial characteristic at a species level, allowing the parasite to successfully thrive under the scarce host availability under saline conditions.

Aesculus hippocastanumL. (European Horse-chestnut) constitutes a biogeographical relict species of the Balkan Peninsula, occurring in isolated and topographically distinct localities in Albania, Bulgaria, Greece and North Macedonia. Despite its great botanical, ornamental and pharmaceutical value, a thorough investigation ofAe. hippocastanumhabitat diversity in its native distribution range has not been conducted yet. The present study aims at the syntaxonomic classification and ecological features of plant communities dominated by this species across its overall native distribution range. On the basis of 55 phytosociological relevés, five ecologically, floristically, and spatially well differentiated clusters were identified, with the main revealed gradients of differentiation being geographic location (longitude, latitude), altitude, annual precipitation and precipitation seasonality. The distinct microhabitats with a special refugial character where these plant communities occur meet the species’ requirement for relatively high air and soil humidity. They have allowed the preservation ofAe. hippocastanumthrough time highlighting their great conservational value. The last one could be useful for the implementation of some appropriate measures for effective conservation of these communities.