BOTANICA SERBICA
Volume 48
Issue 2
2024

Dedication in memory of Nedeljko Košanin (editorial)
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Exploration of secondary metabolites from green algae as antimicrobial agents: A comprehensive review
Elsa Shibu Sruthy and Edathiruthi Kottukkal Chandran Baiju
Pages 127–140
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ABSTRACT:  A number of advancements have been made in algal technology in different fields, such as medical, cosmetic, and pharmaceutical. Green algae (Chlorophyta) are a group of photosynthetic organisms which live in both aquatic and terrestrial environments. They are a potential source of bioactive compounds for the treatment and prevention of a wide range of infectious diseases caused by microorganisms. These compounds also possess anti-inflammatory, antioxidant, anticoagulant, antitumor, and immunomodulatory properties. A wide variety of bioactive compounds are produced, including polysaccharides, which exhibit antimicrobial properties capable of interfering with the cell walls, membranes, and nucleic acids of microorganisms. Membrane fluidity, permeability, or integrity can be affected by polyphenols and fatty acids which scavenge free radicals, chelate metal ions, or disrupt enzymes and membranes. Proteins and peptides form pores within the membranes which bind to specific receptors or inhibit enzymes. Adaptation to adverse environmental conditions, such as temperature extremes, photooxidation, salinity, or osmotic stress, results in the formation of bioactive compounds by altering the physiological and biochemical pathways of algae for the maintenance of cellular homeostasis. With changing consumer preferences and an increase in the number of resistant microorganisms, it is critical to seek novel antimicrobial compounds from green algae. The search for novel bioactive compounds with antimicrobial properties from green algae may serve as an alternative in the light of increased drug resistance in microorganisms. However, in vitro and in vivo evaluations of the safety, efficacy, and mechanism of action of the antimicrobial compounds from green algae require more research. Providing an overview of previous endeavours in this emerging field, this review provides perspectives and a summary of the bioactive compounds responsible for the antimicrobial properties of green algal extracts.

KEY WORDS:  Chlorophyta, bioactive compounds, antibacterial, antifungal, antiviral, drug resistance.

Determination of the chemical composition, DNA cleavage, binding and antioxidant activities of Vincetoxicum scandens
Emine Kılıçkaya Selvi , Seher Güven, Nilgün Güler and Kamil Coşkunçelebi
Pages 141–149
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ABSTRACT:  Vincetoxicum members offer important qualities in both conventional and modern medicine. In the present study, V. scandens from the northeast of Turkey (Trabzon city) was investigated for its phenolic compounds, antioxidant activities, DNA cleavage and binding effects. Phenolic compounds of the V. scandens methanol extract were analysed by high performance liquid chromatography (HPLC-DAD), while their total phenolic and total flavonoid contents were determined spectrophotometrically. The antioxidant potential of the extract was characterised using DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2 ́-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)), and FRAP (ferric re- ducing antioxidant power assay) tests. In addition, the DNA cleavage and binding features of the V. scandens extract were studied using pBR322 DNA and CT- DNA, respectively. The results indicated that the V. scandens methanol extract contained a large amount of catechin, as well as a high total phenolic and total flavonoid content. On the other hand, the DPPH and ABTS antioxidant tests revealed that V. scandens did not exhibit high antioxidant activity. The methanol extract of the studied plant was also rich in catechin, p-coumaric acid and vanillic acid. While the V. scandens methanol extract exhibited weak antioxidant and DNA cleavage activity, it showed DNA binding activity at 50 μM, thus demonstrating the potential to be an intercalation agent in this concentration. This study provides the first report on the total phenolic content, total flavonoid content, DNA cleavage and DNA binding activity as well as antioxidant activity of V. scandens.

KEY WORDS:  Antioxidant activity, DNA cleavage, HPLC-DAD, Vincetoxicum scandens

Leaf shape and size variability of Dryas octopetala in the Central Great Caucasus (the Kazbegi region, Georgia) based on traditional and geometric morphometrics
Jana Ekhvaia, Otar Abdaladze, Tamar Jolokhava, and Arsen Bakhia
Pages 151-162
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ABSTRACT: While soil pH is known to be a key driver of plant species composition, we still have a poor understanding of the quantification of the responses of leaf traits to different soil types, especially in highly sensitive alpine environments susceptible to global environmental changes. By combining traditional and modern geometric morphometrics we aimed to bridge the existing gap and determine whether certain leaf traits reliably separate evergreen Dryas octopetala populations residing in the subalpine-alpine zone of the Kazbegi region, in the eastern part of the Central Great Caucasus in Georgia. To achieve this aim, three populations of D. octopetala were analysed through traditional and, for the first time, modern geometric morphometrics. Both methods revealed congruent results indicating significant differences in leaf shape and size in locations with similar climatic conditions but different soil pH environments (acid vs neutral to slightly alkaline) thus suggesting that D. octopetala exhibits stronger leaf morphological plasticity (wider and larger leaves vs narrower and smaller leaves) to respond to changes in the soil pH gradient. In addition, modern geometric morphometrics, with its high degree of precision as an accessible and inexpensive method, could be advantageous for researchers and scientists seeking to gain a deeper understanding of plant species’ unique responses to varying environmental conditions.

KEY WORDS:  alpine ecosystems, Caucasus, landmarks, soil pH, leaf morphological plasticity

Exploring the potential of bilberry extracts as natural antifungal and bioherbicidal agents in agriculture: composition and antioxidant activity
Yusuf Bayar, Melih Yılar, Hüseyin Akşit, and Nusret Genç
Pages 163-172
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ABSTRACT:  This study aims to investigate the composition of the leaf essential oil and the total phenolic and flavonoid contents as well as the antioxidant activity of the n-hexane, ethyl acetate, and methanol extracts of Vaccinium myrtillus leaves collected from two different locations (Muğla and Mersin, Turkey). In addition, the antifungal activity against Sclerotinia sclerotiorum (SS), Fusarium oxysporum f sp. melonis (FOM), Fusarium oxysporum f sp. cucumerinum (FOC), and Rhizoctonia solani (RS) and the bioherbicidal activity against Taraxacum officinale and Rumex crispus were evaluated for the first time. The methanolic extract inhibited mycelium growth of SS, FOM, FOC, and RS in a dose-dependent manner. No significant difference was observed in antifungal activity between the two different collection sites. In the bioherbicidal activity tests, the methanol extract of the fruits completely suppressed the root-shoot development of Taraxacum officinale, while also significantly inhibiting the root-shoot development during the seed germination of Rumex crispus compared to the control group at 3 mg/mL concentration for both locations. Based on the results of the GC/MS analysis, the major constituents identified in the leaf essential oils collected from the Muğla and Mersin locations were α-pinene (29.16%/15.75%), eucalyptol (22.19%/26.46%), linalool (12.66%/25.27%), and linalyl acetate (7.43%/2.71%). The total phenolic and flavonoid contents of the plant extracts for the Muğla and Mersin samples were determined as (42.80‒157.58 GAE/g extracts), (29.38‒151.44 GAE/g extracts) and (10.52‒37.88 QE/g extracts), (14.81‒44.18 QE/g extracts) respectively. In addition, the plant exhibited significant antioxidant activity. These findings indicate quantitative differences in the chemical composition of the essential oils between the two geographical locations. These findings are significant as they provide insights for the development of new natural antifungal agents with potential applications in agriculture.

KEY WORDS:  Antioxidant, antifungal, Vaccinium myrtillus, essential oil, bioherbicidal activity

Clinopodium menthifolium subsp. menthifolium in the Central Balkan Peninsula - essential oil composition in relation to climatic conditions
Violeta Slavkovska, Miloš Zbiljić and Danilo Stojanović
Pages 173–184
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ABSTRACT: The compositional dependency of the essential oil of Clinopodium menthifolium subsp. menthifolium (Lamiaceae) on ecological conditions has not yet been investigated. In pursuit of this objective, we assessed the quantity and quality of the essential oil in plants from 11 natural populations from the Central Balkans and one cultivated plant. In order to determine the correlations between essential oil variations and environmental conditions, each habitat was characterised by 36 climatic and 19 bioclimatic parameters. Despite inhabiting diverse climatic zones, altitudes, and biogeographical regions, no significant differences were observed in the yield and qualitative and quantitative composition of the essential oils among the analysed plants. All the samples exhibited essential oil yield ≥ 0.5%, V/w, with piperitone epoxide as the major compound. Among the identified compounds, only limonene and (E)-caryophyllene demonstrated dependence on bioclimatic parameters. The bioclimatic parameters which influence the presence of a larger number of compounds are annual temperature range and the precipitation of the wettest quarter. The consistent quantity and quality of the essential oils of C. menthifolium subsp. menthifolium indicate their probable adaptive significance and could serve as chemotaxonomic features of this taxon.

KEY WORDS:  Calamintha sylvatica, volatile compounds, bioclimatic parameters, Central Balkans, piperitone epoxide, limonene

The protective role of exogenous proline in pepper callus exposed to long–term cold stress
Esra Koç and Belgizar Karayiğit
Pages 185–193
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ABSTRACT: Cold stress is one of the main abiotic stress factors which restricts pepper growth and development. Thus, identifying alternative strategies is critical to reduce cold damage in peppers. This study evaluated the effect of exogenous proline in reducing cold stress damage in pepper callus. For this purpose, callus was obtained from the hypocotyl explants of germinated seedlings under in vitro conditions. 0, 12 and 24 mM proline were applied to the callus and developed under the same photoperiodic settings at 4°C, 8°C, 16°C and 24°C. Low temperatures increased H₂O₂ and MDA production with the highest H₂O₂ and MDA amounts determined at 4°C. Proline applications decreased the content of H₂O₂ at low temperatures, whereby 24 mM proline caused a significant decrease in the amount of H₂O₂ at 4°C. The lowest MDA accumulation was determined in the 12 mM proline application. The data indicated that the total phenolic content of pepper callus decreased with decreasing temperatures. However, the application of proline increased the total phenolic amounts with the increase in its concentration. DPPH radical scavenging activity, FRAC and total protein content decreased with decreasing the temperature to 4°C and 8°C. However, both exogenous proline applications increased DPPH radical scavenging activity, FRAC and total protein at 4°C and 8°C. The results indicated that the metabolic pathways are triggered by the application of exogenous proline.

KEY WORDS:  Capsicum annum, free radical, lipid peroxidation, oxidative stress, tissue culture, tolerance

Bio-based solution for improving plant growth under unfavourable conditions: Bacterial inoculants for bird’s foot trefoil and orchardgrass grown in acid soil
Magdalena Knežević, Tanja Berić, Aneta Buntić, Zoran Dinić, Dušica Delić, Slaviša Stanković and Olivera Stajković-Srbinović
Pages 195–205
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ABSTRACT: The agricultural industry is constantly searching for new solutions to increase the productivity and nutritional value of crops under various conditions. Microbial inoculants have emerged as an alternative to traditional chemical fertilisers which could enhance crop productivity in acid soils - a major problem in modern agriculture. The aim of this research was to evaluate the effects of Bacillus megaterium and Mesorhizobium sp. on the seed germination of bird’s foot trefoil and orchardgrass under low pH (in vitro), as well as the nutrient composition of plants grown in acid soil. A positive impact of bacterial inoculation on seed germination was observed at pH 5 and 6 for both plant species. The content of macro- and microelements was within the range of optimal values for both plant species. This research provides valuable insights into the potential benefits of using bacterial inoculants to improve the seed germination and nutrient composition of plants grown in acid soils.


KEY WORDS:  acid soil, Bacillus megaterium, Mesorhizobium sp., Dactylis glomerata, Lotus corniculatus, nutrient composition

Red-list of moss species of Serbia: 2024 assessment
Marko S. Sabovljević, Jovana P. Pantović, Pavel Širka, Milorad M. Vujičić, Aneta D. Sabovljević and Beáta Papp
Pages 207–222
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ABSTRACT: The new extinction risk assessments of the mosses of Serbia have been completed. Based on the available data, 27.18% of Serbian moss flora (174 species) is under threat (status 2024). Nearly 20% (129 species) of Serbian moss flora is considered to be Data Deficient (DD) and 5.16% (33 species) Near Threatened (NT). These findings clearly indicate the urgent need for field investigation and species biology research in order to define the major threats and adequate conservation measures.

KEY WORDS:  threat assessment, conservation, bryophyte, extinction risk

Propagation of Campanula bayerniana (Campanulaceae) by seeds as a reproduction model for the conservation of threatened small-seed plant species
Anna Asatryan, Yekaterina Shcherbakova, Alexander Rudov and Yevgenia Navasardyan
Pages 223–229
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ABSTRACT: The in vitro seed propagation of small seeded Campanula species often incurs complications in the manual handling of the tiny seed material from seed sterilisation to seedling transplantation in soil. The lack of a simple and effective protocol which minimises manual operations makes the propagation of such species both challenging and inefficient. This study aimed to develop a protocol for the seed reproduction of threatened Campanula and other threatened small-seed plant species. The method was successfully tested on Campanula bayerniana subsp. bayerniana. The saplings were cultivated over a 5-month period through seed germination under in vitro conditions followed by their transfer to containers with a soil mix. The protocol employs small filter paper discs on which the seeds germinate and continue their development in soil substrate until the full biodegradation of the discs. The method involves surface treatment of the seeds with potassium permanganate solution, thus avoiding additional washing phases and direct contact with the seeds and seedlings, thereby preventing mechanical damage. This also facilitates the handling of each seed separately, minimising seed loss particularly when working with a small number of seeds. This study is also the first known example of the ex situ propagation of Campanula bayerniana.

KEY WORDS:  Campanula bayerniana, ex situ conservation, seed reproduction, small-seeded plant species

Chemophenetic investigation of epicuticular n-alkanes in Juniperus L. section Juniperus L. from the Balkans
Nemanja Rajčević, Peđa Janaćković and Petar D. Marin
Pages 231-237
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ABSTRACT: Junipers are one of the most diverse groups of gymnosperms today. They are adapted to arid areas of the world. In this study, we analysed the chemical composition of the leaf n-alkanes of 170 individuals belonging to Juniperus communis subps. communis, J. communis var. saxatilis, J. deltoides and J. macrocarpa from the Balkans. Localities with at least two sympatric populations were chosen to study the chemical composition in order to limit the influence of environmental factors on the chemical composition. The leaf n-alkanes were extracted from the leaves with n-hexane and analysed using GC-MS. In all of the samples, n-C33 was the dominant alkane, with n-C29, n-C31 and n-C35 comprising over 80% of the n-alkane profile. The percentages of these dominant n-alkanes were taxon-specific, thus indicating their chemotaxonomic significance. In all the multivariate statistical analyses, samples belonging to different taxa were separated from each other. While the n-alkane profile can be used as a chemotaxonomic tool in the differentiation of these four taxa, it did not carry a phylogenetic signal. Instead, it reflected ecological adaptations, showing how different taxa have adapted to different arid environments within the study area.

KEY WORDS:  cuticle, n-alkanes, junipers, chemotaxonomy, Juniperus communis, Juniperus deltoides, Juniperus macrocarpa

TauL1, TauL2 and TauL3 gene-pools of Aegilops tauschii essentially differ in their genetic expression patterns
Alexander Ju. Dudnikov, Gennady V. Vasiliev, Ming Hao, Deng-Cai Liu, Fan Xing, Mehdi Mansouri, Dmitry A. Afonnikov and Nikolay A. Shmakov
Pages 239–246
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ABSTRACT: Aegilops tauschii is a wild diploid goat-grass which occupies a vast range in Central Eurasia and comprises three different gene-pools: TauL1, TauL2, and TauL3. Multivariate statistical analysis of the transcriptomes from the leaf tissue of 40 A. tauschii accessions, 18 of TauL1, 20 of TauL2, and 2 of TauL3, revealed that the gene-pools of A. tauschii distinctly and essentially differ in their genetic expression patterns. Statistically significant differential gene expression of 2349, 376, and 272 were observed between TauL1 and TauL2; TauL1 and TauL3; TauL2 and TauL3, respectively. These findings indicate substantial adaptive intraspecies divergence in A. tauschii.

KEY WORDS:  adaptation, goat-grass, differentially expressed genes, intraspecies divergence, transcriptomes

An ethnobotanical study on the usage of wild plants from Tara Mountain (Western Serbia)
Milan Gavrilović, Milica Milutinović, Bojan Zlatković, Maja Radulović, Milica Miletić, Milica Trajković, Zora Dajić Stevanović and Pedja Janaćković
Pages 247-262
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ABSTRACT: In this study an ethnobotanical survey was conducted in western Serbia (Mt. Tara) with the aim of collecting and preserving the traditional botanical knowledge. A group of local inhabitants (56) was interviewed using semi-structured questionnaires. The Relative Frequency of Citation (RFC) and Jaccard Index (JI) were calculated. There are 78 wild plant species recorded. The reported plant species belong to 34 families, where the families Rosaceae (41.18%), Asteraceae (23.53%) and Lamiaceae (20.59%) were dominant. Out of 78 documented plants, 70 plants (89.74%) are used in folk medicine, 42 (53.85%) in human nutrition, 22 (28.20%) in animal nutrition, 14 (17.95%) plants are used for miscellaneous purposes, while two plants (2.56%) are used in ethnoveterinary medicine. The highest RFC was recorded for Vaccinium myrtillus (0.38), followed by Urtica dioica (0.34), and Hypericum perforatum (0.25) and Fragaria vesca (0.25). The most frequently used mode of preparation was as an infusion (70.51%), while the most used plant part was the leaf (56.41%) followed by the flower/inflorescences (37.18%) and aboveground parts (28.21%). The highest degree of similarity was determined with studies conducted in close proximity (Mt. Zlatibor, JI 33.04). Local recipes and new usage of some well-known traditional plants in Serbia and the Balkans were documented.

KEY WORDS:  Balkans, wild plants utilisation, folk medicine, human and animal nutrition, Vaccinium myrtillus

Centaurea ozrenii (Asteraceae) ‒ a new local endemic and extremely rare species from Mt. Ozren near Sjenica in Serbia
Uroš Buzurović, Gordana Tomović, Ksenija Jakovljević, Snežana Vuksanović, Maja Lazarević, Snežana Dragićević and Marjan Niketić
Pages 263–271
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ABSTRACT: A new species of Centaurea sect. Acrocentron (Asteraceae) was found on the Ozren mountain in southwestern Serbia near Sjenica and named as Centaurea ozrenii. It inhabits xerophilous and steppe-like habitats, on ultramafic geological substrate. Morphologically, it is close to C. calocephala, C. chrysolepis, C. orientalis, C. murbeckii, C. kotschyana and the recently described C. zlatiborensis. The most distinctive morphological features of the new species are undivided to simply pinnatisect (non lyrate) subglabrous leaves, with linear segments, upper leaves with an aristate apex and cream coloured to pale yellow florets of which the outer are much longer than the inner ones. The phyllaries are intermediate in relation to C. calocephala and C. kotschyana. The chromosome number of the new species is 2n = 22. Thorough field investigations confirmed the presence of C. ozrenii only at this localized site on Mt. Ozren with a population of 13 clusters of individuals with 23–52 flowering stems in an area of about 50 m². Applying the IUCN Red List categories and criteria to the available data categorised C. ozrenii as a Critically Endangered (CR) species.

KEY WORDS:  Balkan flora, sect. Acrocentron, new species, taxonomy, chromosome number

A nomenclatural and taxonomic re-evaluation of neglected Centaurea candelabrum Hayek & Košanin (sect. Acrocentron, Asteraceae) and related serpentine endemics from the Balkan Peninsula
Dmitar Lakušić, Nevena Kuzmanović, Lulëzim Shuka, Jelica Novaković and Snežana Vukojičić
Pages 273–284
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ABSTRACT: Centaurea sect. Acrocentron comprises several taxonomically intricate groups of taxa, including the Balkan endemic obligate serpentinophytes: C. melanocephala, C. candelabrum and C. albertii. Despite its distinctive morphological characteristics, C. candelabrum was considered conspecific with C. melanocephala. A similar situation pertains to C. albertii, which has largely been considered a synonym of C. melanocephala. Considering that several recent floristic works treat these taxa as separate species distributed in different serpentinite areas of the Balkans, the main objectives of our study were to analyse the taxonomic and chorological relationships between them, and to propose a new taxonomic concept. Our study was based on an extensive revision of herbarium material, including the type specimens, personal field data and observations of living plants. Our comprehensive study showed that the plants previously recognised as C. melanocephala from the Stolovi mountain in central Serbia and those previously recognised as C. candelabrum from northern Albania deserve the rank of distinct species. These species can be easily distinguished from each other by a number of characters, including their general habitus, the dimensions and shape of the basal leaves, and the indumentum of the involucral bracts. Given the only slight differences observed between the populations in Kosovo and Albania, the question of whether C. albertii is conspecific with C. candelabrum or deserves an independent taxonomic status remains unresolved until further detailed integrative studies are conducted. In view of the clear differences in morphological and ecological characteristics which exist within this group compared to other representatives of sect. Acrocentron, we propose the separation of the studied taxa into a separate C. melanocephala complex, as outlined in this paper.

KEY WORDS:  Centaurea melanocephala complex, lectotype, overlooked taxa, typification

New records and noteworthy data of plants, algae and fungi in SE Europe and adjacent regions, 18
Gordana Tomović, Marko S. Sabovljević, Dimitar Stoykov, Marjan Niketić, Petya Boycheva, Mariya Kaschieva, Danijela Vidaković, Jelena Krizmanić, Vladan Djordjević, Svetlana Krdžić, Siniša Škondrić, Jelena Knežević, Ranko Perić, Boris Assyov, Dragana Jenačković Gocić, Irena Raca, Sanja Šovran, Slađana Popović, József Pál Frink, Andrea Sass-Gyarmati, Miruna-Maria Ștefănuţ and Aneta D. Sabovljević
Pages 285-296
Full reference | Abstract | Full text PDF

ABSTRACT: This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: cyanobacteria Pseudanabaena thermalis, lichenised fungi Acrocordia gemmata, parasitic fungi Peniophora tamaricicola, saprotrophic fungi Hyphonectria buxi, diatom alga Diatoma elongata, mosses Sphagnum medium, Rhizomnium magnifolium, and Weissia squarrosa, monocots Gymnadenia frivaldii, Hemerocallis lilioasphodelus, Orchis × angusticruris and Pistia stratiotes, and dicots Astragalus angustifolius subsp. balcanicus, Broussonetia papyrifera, Datura innoxia and Montia arvensis.

KEY WORDS:  new report, Acrocordia gemmata, Astragalus angustifolius subsp. balcanicus, Broussonetia papyrifera, Datura innoxia, Diatoma elongata, Gymnadenia frivaldii, Hemerocallis lilioasphodelus, Hyphonectria buxi, Montia arvensis, Orchis × angusticruris, Peniophora tamaricicola, Pistia stratiotes, Pseudanabaena thermalis, Rhizomnium magnifolium, Sphagnum medium, Weissia squarrosa, SE Europe.

New records and noteworthy data of plants, algae and fungi in SE Europe and adjacent regions, 19
Marko S. Sabovljević, Gordana Tomović, Sorin Ștefănuţ, Vladan Djordjević, Sara Stanković, Sanja Z. Djurović, Božo Frajman, Petya Boycheva, Mariya Kaschieva, Péter Szűcs, Aneta D. Sabovljević, Ivana Trbojević, Aleksandra Marković, Ljubica Vlaović, Danijela Vidaković, Dragana Jenačković Gocić, Danijela Nikolić, Dimitar Stoykov, Svetlana Krdžić, Vasilică-Claudiu Chinan, Ciprian Claudiu Mânzu, Boris Assyov and Marjan Niketić
Pages 297-307
Full reference | Abstract | Full text PDF

ABSTRACT: This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: mycorrhizal fungus Russula sapinea, parasitic fungus Podosphaera polemonii, saprotrophic fungi Ophiognomonia melanostyla and Plagiostoma apiculatum, diatom alga Nitzschia reskoi, stonewort Nitellopsis obtusa, liverwort Mannia triandra, mosses Buxbaumia viridis and Leptodon smithii, monocots Epipactis purpurata and Orchis × beyrichii and dicots Euphorbia orjeni, Fallopia × bohemica, Nuphar lutea and Saxifraga pedemontana subsp. cymosa.

KEY WORDS:  new report, Buxbaumia viridis, Epipactis purpurata, Euphorbia orjeni, Fallopia × bohemica, Leptodon smithii, Mannia triandra, Nitellopsis obtusa, Nitzschia reskoi, Nuphar lutea, Ophiognomonia melanostyla, Orchis × beyrichii, Plagiostoma apiculatum, Podosphaera polemonii, Russula sapinea, Saxifraga pedemontana subsp. cymosa, SE Europe

Physiological characterisation of aquatic traps in the epiphytic carnivorous plant Utricularia humboldtii
Lubomír Adamec
Pages 309–314
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ABSTRACT: The suction traps of aquatic Utricularia species are discoid bladders, 1–6 mm long, with their lumen isolated by a mobile trapdoor from the ambient medium. Water is pumped out of the traps to maintain the negative pressure in the reset traps. When a prey animal touches the sensory hairs on the trapdoor it opens, the ambient water along with the prey is sucked inside and the trapdoor is closed again. Utricularia humboldtii is a robust, semiaquatic–epiphytic or terrestrial species from the generic section Orchidioides from South America. The efficiency of its aquatic traps was measured based on trap firing and resetting rates as well as changes in trap thickness due to both mechanically stimulated and spontaneous firings using an electronic sensor. The U. humboldtii traps exhibited relatively low firing and resetting rates. These values are 2 to 20 times lower than those in other aquatic Utricularia species reported in the literature. These results together with the low aerobic respiration rate of sliced traps indicate that the less efficient aquatic traps in U. humboldtii are specialised for catching fine prey items in bromeliad water tanks. A marked lag-period in trap resetting was found to occur during the first 30 min after firing, contradicting the accepted concept of continuous water pumping. Spontaneous trap firings were also observed with the same magnitude as that in stimulated firings. This implies that spontaneous firings occur consistently in all the tested aquatic Utricularia species. However, although they relate to the continuous water pumping mechanism of the traps, their physiological importance has not been fully elucidated.

KEY WORDS:  trap firing, water pumping rate, trap thickness, aerobic respiration rate