Lubomír Adamec

Mineral nutrition of carnivorous plants: A review

Plant carnivory is one of many possible adaptation strategies to unfavorable conditions, mostly low nutrient availability in wet, acid soils. The following issues concerning the mineral nutrition of carnivorous plants are reviewed: the relative importance of carnivory and root nutrition for growth; which nutrients (elements) from prey are of principal importance for growth; the relationship between mineral and organic nutrition based on carnivory; the interactions between carnivory and root mineral nutrition; and the importance of carnivory under natural conditions. Special attention is paid to aquatic carnivorous plants. Studies on mineral nutrition carried out in laboratory and/or greenhouse conditions are discussed separately from those carried out in field conditions. The emphasis of this review is on recapitulation of original data and conclusions of results from a variety of studies that approach carnivorous plants from an ecophysiological point of view.ZusammenfassungDie Karnivorie der Pflanzen ist eine von mehreren Adaptationsstrategien zu ungünstigen Bedingungen, meist zu niedrigem Nährstoffangebot in feuchten, sauren Böden. Es wird eine Übersicht präsentiert über folgende Fragen der Mineralernährung von karnivoren Pflanzen: die entsprechende Bedeutung der Karnivorie und der Wurzelernährung für das Wachstum; welche Nährstoffe (Elemente) von der Beute prinzipielle Bedeutung für das Wachstum haben; welche Beziehung ist zwischen der anorganischen und organischen Ernährung, die auf der Karnivorie beruht; welche Zwischenbeziehung besteht zwischen der Karnivorie und der Mineralernährung durch Wurzeln; und welche Bedeutung hat die Karnivorie unter natürlichen Bedingungen. Eine besondere Aufmerksamkeit ist den aquatischen karnivoren Pflanzen gewidmet. Untersuchungen über Mineralernährung in Labor- und/oder Gewächshausbedingungen werden gesondert von Ergebnissen diskutiert, die unter Feldbedingungen gewonnen wurden. In dieser Übersicht werden nachdrücklich Originaldaten und Schlussfolgerungen aus Ergebnissen verschiedener Studien rekapituliert, die sich mit karnivoren Pflanzen vom ökophysiologischen Standpunkt befassen.

Photosynthetic characteristics of the aquatic carnivorous plant Aldrovanda vesiculosa

Abstract Aldrovanda vesiculosa L. (Droseraceae) is a critically endangered aquatic carnivorous plant. It is considered to be strictly stenotopic. Chemical and physical factors were measured in situ in A. vesiculosa stands at eight sites. The O 2 concentration usually ranged between 0.25–0.28 mM. There was a wide range of pH of 5.04–7.60, but with a median of 7.17. Total alkalinity ranged between 0.16–4.2 meq 1 −1 but was mostly within 1.0–2.7 meq 1 −1 . A high CO 2 concentration was found in all stands; it ranged between 0.14–3.5 mM and was usually within 0.2–0.5 mM. A high CO 2 concentration appeared to be the most important condition for rapid apical growth. It appeared to be a strict CO 2 user with a CO 2 compensation point of 5.9–8.2 μM, a K m of 165 ± 77 μM CO 2 , and a maximum photosynthetic rate of 99 ± 10 mmol kg −1 (FW) h −1 . It was found to be photophilous and exhibited a light compensation point of 6.0 W m −2 . A. vesiculosa grew in unshaded, and also shaded stands with only 18–24% of incident irradiance at the water surface. Photosynthetic rates rose from 15 to 34°C. The highest photosynthetic rate was found in young apical shoot segments and it declined toward the bases.

Utricularia carnivory revisited: plants supply photosynthetic carbon to traps

The rootless, aquatic Utricularia species belong to the largest and most cosmopolitan carnivorous plant genus. Populations of Utricularia plants are an important component of many standing, nutrient-poor, and humic waters. Carbon (C) allocation is an aspect of Utricularias ecophysiology that has not been studied previously and there is considerable uncertainty about the functional and ecological benefit of the trap-associated microbial community and the potential role played by C exudation in enhancing plant-microbe interactions. A 13C-labelling experiment was conducted in greenhouse conditions to determine the C allocation between plant tissues of increasing age and trap fluid in two Utricularia species. Both species allocated a majority of the newly fixed C into the fast growing shoot apex (46.1+/-8.6% in U. vulgaris and 56.1% in U. australis). Carbon allocation rapidly decreased with increasing age of the shoot, constituting only 8.0+/-4.0% and 6.7% of the total newly fixed C in the oldest analysed segments in U. vulgaris and U. australis, respectively. In the trap-bearing shoot segments, the ratio of C exuded into the trap fluid to that in plant tissues increased markedly with age--in the oldest analysed segments twice as much newly fixed C was allocated into the trap fluid than the plant tissue. Overall, a significant amount of the newly fixed C, approximately 25% (U. vulgaris) and 20% (U. australis), was allocated to the trap fluid. The importance of C exudation for the development of the microbial community associated with the traps as well as for the growth and ecology of aquatic Utricularia is discussed.

Rootless Aquatic Plant Aldrovanda Vesiculosa: Physiological Polarity, Mineral Nutrition, and Importance of Carnivory

Various ecophysiological investigations are presented in Aldrovanda vesiculosa, a rootless aquatic carnivorous plant. A distinct polarity of N, P, and Ca tissue content per dry mass (DM) unit was found along Aldrovanda shoots. Due to effective re-utilization, relatively small proportions of N (10 – 13 %) and P (33 – 43 %) are probably lost with senescent leaf whorls, while there is complete loss of all Ca, K, and Mg. The total content of starch and free sugars was 26 – 47 % DM along adult shoots, with the maximum in the 7th – 10th whorls. About 30 % of the total maximum sugar content was probably lost with dead whorls. The plant was found to take up 5 – 7 times more NH4+ to NO3− from a mineral medium. Under nearly-natural conditions in an outdoor cultivation container, catching of prey led to significantly more rapid growth than in unfed plants. DM of the fed controls was 48 % higher than in the unfed plants. The controls produced 0.69 branches per plant, while the unfed plants did not produced any. However, the N and P content per DM unit increased by 6 – 25 % in the apices and the first 6 whorls in the unfed variant, as compared to the fed controls. It may be suggested that carnivory is very important for Aldrovanda.

Mineral nutrient relations in the aquatic carnivorous plant Utricularia australis and its investment in carnivory

Aquatic rootless carnivorous plants usually grow in nutrient-poor waters and take up all nutrients through their shoots, from either water or prey. The carnivorous plant Utricularia australis was sampled from 30 locations in the Třeboň basin, Czech Republic, with the aim of investigating the plants mineral nutrient economy in relation to its carnivorous habit. Relationships were sought between, firstly, mineral nutrient levels in the ambient water together with prey quantity captured in traps and, N, P, K, Na, Ca, and Mg contents of shoot tissues, and, secondly, the proportion of total plant biomass attributable to traps (i.e., investment in camivory). Even at very oligotrophic sites with low prey capture rates, shoot N and P content was always well above the level below which growth limitation could occur. Plants recycled at least 57 % of their N and as much as 81 % of their P from senescent shoots, although they lost all of the K, Na, Ca, and Mg from senescing tissues. The P and K content of traps was much greater than that in leaves. Regression analyses revealed much greater uptake of N, P, and K from prey than from the ambient water. The proportion of total biomass invested in traps (range 23-61 %) was positively correlated with CO 2 concentration, but negatively with shoot N content. It is suggested that shoot N content acts as a key endogenous factor regulating investment in trap biomass through a negative feedback mechanism. Any decline in shoot N content, for whatever reason, stimulates an increase in trap production, resulting in enhanced prey catching and, concomitantly, an increase in shoot N content. A reduction in trap proportion then follows and the cycle starts again.

Genome size and genomic GC content evolution in the miniature genome‐sized family Lentibulariaceae

• Lentibulariaceae contains species with the smallest genome size in tracheophytes, yet data are available only for 8% of its species. This prevents understanding of the history of miniaturization events and their possible reasons. Nothing is known about the variation of genomic DNA base composition. • Genome size and genomic GC content were analyzed with flow cytometry in 119 Lentibulariaceae species. The evolution of both parameters and their correspondence with several ecological traits was tested by sequence-based phylogeny. • Genome size ranged from 1C=73 to 1C=1471 Mbp, with 19 species found to be smaller than Arabidopsis. Miniaturizations have a long history in Utricularia; they also accompany the evolution of Genlisea and two species of Pinguicula. The absence of correlation between genomic parameters and ecological variables suggests that the driving forces of miniaturization are of intrinsic nature. Genome size dynamics associates with extreme variation of GC contents (34.0%–45.1%), being the highest among tracheophyte families. The extremely low GC contents, however, must clearly have evolved with contributions from processes other than sole DNA removal. • The extreme dynamics of Lentibulariaceae genomes provides a unique opportunity for studying genome miniaturization and GC content variation. Hopefully, our study will facilitate the selection of proper model species.

Ecological requirements and recent European distribution of the aquatic carnivorous plantAldrovanda vesiculosa L.—A review

Aldrovanda vesiculosa, a critically endangered aquatic carnivorous plant, is a species rapidly vanishing from Europe. A map of its recent European distribution is given. Of its earlier distribution area covering a substantial part of Europe, only a few native sites in Hungary, Poland, Romania, Russia and Ukraine remain. On the basis of the literature, field research inAldrovanda habitats, and experience of its cultivation both in culture and in the field, its ecological requirements and habitat characteristics are reviewed. The most important requirements appear to be a high CO2 concentration, a medium concentration of humic acids in the water, warm water of high transparency, and a very low biomass of accompanying aquatic plants. The possibility of forming new substitute localities ofAldrovanda is discussed.

Ecophysiological characterization of dormancy states in turions of the aquatic carnivorous plant Aldrovanda vesiculosa

Two main dormancy states, innate and imposed dormancy, were characterized in turions (winter buds) of the aquatic carnivorous plant Aldrovanda vesiculosa L. (Droseraceae) kept at 3 ± 1 °C in a refrigerator over the winter. As a result of the breaking of imposed dormancy by a temperature increase (at 15 – 20 °C), some of the turions rose to the water surface within 1 – 3 d and germinated. Turion leaves contained large lacunae with a slimy reticulum and were filled by water over winter. As a result of breaking imposed dormancy, the proportion of gas volume in inner turion leaves rose from 10 – 20 % to 100 % of leaf lacunae volume. The aerobic dark respiration rate of the turions [0.74 – 1.5 μmol O2) kg−1(FM) s−1] slightly increased during innate dormancy after 1 – 2 d at 20 °C, while it was almost constant during the breaking of imposed dormancy. The anaerobic fermentation rate of the turions was only 1.5 – 7 % of the oxygen respiration rate and also was constant during the breaking of imposed dormancy. In turions, the content of glucose, fructose, and sucrose was the same for the two states of dormancy, but starch content was greatly reduced for the imposed dormancy (10 – 11 vs. 32 % DM). It may be suggested that a temperature increase causes an increase of fermentation or respiration which is responsible for the evolution of gas in turion lacunae and, thus, for turion rising.

Genetic variation within the endangered species Aldrovanda vesiculosa (Droseraceae) as revealed by RAPD analysis

Aldrovanda vesiculosaL. (Droseraceae) is an endangered aquatic carnivorous plant species inhabiting standing dystrophic waters across Europe, Asia, Australia, and Africa. Despite its widespread occurrence, its population is patchily distributed. Proliferation in these mostly isolated habitats is largely clonal by shoot branching. We assessed the level of variation of random amplified polymorphic DNAs (RAPDs) in a collection of plants from Europe, Asia, and Australia to study the distribution of genetic variation. The low level of genetic variation found in a previous allozyme study was confirmed in that only 14% of 151 RAPD primers gave polymorphic banding patterns. The proportion of polymorphic bands over all primers was 37% with a mean Jaccard distance of 0.62. Cluster analysis and ordination analysis identified three clusters of closely related plants: an Australian and Japanese accession, a Ukrainian, Russian, and Rumanian accession, and a third accession from Poland and Germany. Although the plants from Germany and NW Australia did not differ from other members of the same RAPD cluster on the basis of morphological or physiological characteristics, these plants were clearly of recombinant origin based on the results of compatibility tests. Remaining accessions possessed RAPD patterns consistent with predominantly asexual mode of reproduction. By focussing on the modes of reproduction in combination with physiological and

Tissue mineral nutrient content in turions of aquatic plants: does it represent a storage function?

Turions are frost resistant, vegetative dormant organs produced by aquatic plants. Tissue N, P, K, Ca, and Mg content was estimated in turions of 5 rooting, non-carnivorous plant species of the genera Caldesia, Hy- drocharis, and Potamogeton and in 7 rootless carnivorous plant species of the genera Aldrovanda and Utricularia, and compared with concentrations of these nutrients in ambient waters either in the fi eld or in culture. Mean turion content of N in all species was 1.87 % DW, P 0.26 %, K 0.65 %, Ca 0.15 %, and of Mg 0.19 % DW. Of all nutri- ents, only turion K content differed signifi cantly between carnivorous and non-carnivorous species (0.48 ± 0.03 vs. 1.04 ± 0.10 % DW). For all plant species and sites (n = 18), turion nutrient content did not depend on nutrient concentrations in the ambient water at the time of turion initiation. Results of a literature survey conducted for the 12 plant species revealed that mean turion nutrient content was moderately (N, P) or markedly (K, Ca, Mg) lower than shoot or leaf nutrient content for the same 12 species. In conclusion, turions of aquatic plants also represent storage organs for mineral nutrients (N, P) though their storage function is presumably less distinct than in the case of carbohydrates.