Laretia Acaulis Research Articles

Isolation and cross-amplification of the first set of polymorphic microsatellite markers of two high-Andean cushion plants

In the southern Andes mountains (27-39◦S) Azorella madreporica and Laretia acaulis, two Apiaceae cushion plant species commonly known as yaretas, conform a well-established altitudinal vegetation belt along the lower Andean zone. These species have been considered as fundamental components of several ecological dynamics within their communities; however, high mountain ecosystems are increasingly threatened worldwide by natural and anthropogenic pressures and the southern Andes are not the exception. Recognizing that genetic information is crucial for the success of any conservation or restoration initiative inwild populations, we developed and cross-amplified 28 specifically designed microsatellite markers (14 in A. madreporica and 14 in L. acaulis), and also tested the cross amplification of 25 markers from the related species Azorella selago. In a region which is particularly vulnerable to global change trends, this new polymorphic microsatellite loci will be useful in the study of the genetic diversity of these high-mountain cushion plants, which are pivotal in the structuring of their native ecosystems.

Carbohydrate reserves in the facilitator cushion plant Laretia acaulis suggest carbon limitation at high elevation and no negative effects of beneficiary plants.

The elevational range of the alpine cushion plant Laretia acaulis (Apiaceae) comprises a cold upper extreme and a dry lower extreme. For this species, we predict reduced growth and increased non-structural carbohydrate (NSC) concentrations (i.e. carbon sink limitation) at both elevational extremes. In a facilitative interaction, these cushions harbor other plant species (beneficiaries). Such interactions appear to reduce reproduction in other cushion species, but not in L. acaulis. However, vegetative effects may be more important in this long-lived species and may be stronger under marginal conditions. We studied growth and NSC concentrations in leaves and stems of L. acaulis collected from cushions along its full elevational range in the Andes of Central Chile. NSC concentrations were lowest and cushions were smaller and much less abundant at the highest elevation. At the lowest elevation, NSC concentrations and cushion sizes were similar to those of intermediate elevations but cushions were somewhat less abundant. NSC concentrations and growth did not change with beneficiary cover at any elevation. Lower NSC concentrations at the upper extreme contradict the sink-limitation hypothesis and may indicate that a lack of warmth is not limiting growth at high-elevation. At the lower extreme, carbon gain and growth do not appear more limiting than at intermediate elevations. The lower population density at both extremes suggests that the regeneration niche exerts important limitations to this species' distribution. The lack of an effect of beneficiaries on reproduction and vegetative performance suggests that the interaction between L. acaulis and its beneficiaries is probably commensalistic.

Facilitation consequences for reproduction of the benefactor cushion plant Laretia acaulis along an elevational gradient: costs or benefits?

Environmental stress may favour facilitative interactions among plants but whether these interactions are positive for the benefactor and how this depends on stress factors, remains to be determined. We studied the effect of beneficiary cover and biomass on reproduction of the benefactor cushion plant Laretia acaulis (Apiaceae) in the central Chilean Andes during three years. Study sites were situated along an elevational gradient at 2600, 2800, 3000 and 3150 m a.s.l. This range comprises a cold‐ and a drought‐stress gradient, with moisture increasing and temperature decreasing with elevation. We studied the effect of natural gradients in beneficiary cover and of experimental cover removal on cushion flower and fruit production. Beneficiary cover had a negative effect on flower production but not on infructescence and fruit densities or fruit weights. A positive effect of beneficiaries on the fraction of flowers converted into fruits was detected for hermaphrodite cushions. The effect of beneficiary cover on flowering was independent of elevation or cushion gender, although these latter factors explained most of the variation. Removing the aboveground parts of the beneficiaries positively affected flowering at 2800 m a.s.l. but not at the other elevations. Our results suggest negative effects of facilitation on L. acaulis flowering, but these are neutralized in fruit production. Surprisingly, this conclusion holds along the entire elevational or stress gradient. This suggests that this system of facilitation is evolutionarily stable and not very sensitive to environmental change. It remains to be tested, however, whether facilitation affects fitness via growth and long‐term survival in these slow‐growing alpine cushions.

Parasitism by Cuscuta chilensis and gender affect how the nurse cushion Laretia acaulis increases diversity in Andean alpine communities

AbstractQuestionAlthough there is a large amount of information about the anatomy, physiology and auto ecology of parasitic plants, much less is known about how they affect the interaction among other species and if they present gender preferences when the host is dioecious. The little knowledge available is focused on the effects of parasitic plants on negative plant interactions, but their indirect effects on facilitative interactions remains unexplored. We examined whether the parasitic plant Cuscuta chilensis showed gender preference on its host, the dioecious nurse cushion species Laretia acaulis, and how the presence of the Cuscuta affects relationships between Laretia and its community of beneficiary species.LocationCentral Chilean Andes.MethodsWe randomly sampled 50 L. acaulis cushions infected with Cuscuta, 50 Laretia cushions free of Cuscuta infection, and 50 open sites outside of cushions. We measured the area of each cushion selected, identified cushions as male or female, and identified, counted and recorded the numbers of each other species within cushions and in the open sites. We compared species richness among uninfected Laretia individuals, infected Laretia individuals and open sites, and between infected and uninfected patches within Laretia cushions. Further, we assessed the differences in species assemblage composition between each microhabitat by means of detrended correspondence analysis.ResultsFifteen out of 23 species were more common in Laretia cushions than in the open, non‐cushion habitat. Laretia without Cuscuta harboured 3.9 ± 0.2 species per cushion in comparison to 2.5 ± 0.2 species in open habitats. Infection of Laretia cushions by Cuscuta was female‐biased and this infection was associated with an increase in the nurse plant effects of Laretia, with seven of 23 species more common in Cuscuta‐infected cushions than in cushions without Cuscuta, and a mean of 5.9 ± 0.3 species per Cuscuta‐infected cushion.ConclusionsCuscuta infection showed gender preferences, and this infection increased the facilitative effect of Laretia nurse cushions. This might be related to a decrease in the competitive resistance of the cushion species to colonization by other species (indirect effect) or direct positive effect due to the presence of the parasitic plant (e.g. increases in available soil N). To our knowledge, this is the first documentation of how the indirect effects of a parasitic plant might increase the facilitative effects of a nurse species.

Facilitation of the non‐native Taraxacum officinale by native nurse cushion species in the high Andes of central Chile: are there differences between nurses?

Summary 1. Positive interactions between species are known to play an important role in the dynamics of native plant communities, particularly in stressful habitats. However, their role in plant invasions is less known, although recent studies have started to highlight the importance of positive interactions as a driver of invasion. It has been suggested that facilitative interactions during invasions are not expected to be species-specific. 2. The perennial herb Taraxacum officinale (dandelion) is a conspicuous alien plant species invading the central Chilean Andes. In contrast to other alien species that are restricted to humandisturbed sites at high elevations, T. officinale is frequently observed growing within native plant communities dominated by cushion plants. We selected sites where two cushion species coexist ( Laretia acaulis and Azorella monantha ), and evaluated whether T. officinale is equally associated with the two cushion species or shows a preference for one of them. We assessed facilitative effects of the two cushion species on T. officinale via seedling survival experiments, measurements of photochemical efficiency of photosystem II (Fv/Fm and Φ PSII), reproductive output and recording the differences in soil temperature, humidity and nutrient contents between these cushion species and open areas. 3. Taraxacum officinale was significantly and positively associated with only one of the two cushion species ( A. monantha ). Seedling survival was higher in A. monantha than on L. acaulis or the bare ground. Photochemical efficiency and reproductive output were higher within the two cushion species than outside them. However, performance of T. officinale was significantly better within the cushions of A. monantha than those of L. acaulis . Soil temperature, humidity and contents of nitrogen and phosphorous were similar within the two cushion species; however, potassium was two times higher in the soil beneath L. acaulis than beneath A. monantha . 4. Results indicate that the native cushion species facilitates the establishment and performance of a non-native invasive species, and that this interaction is highly species-specific due to differences in soil nutrient content beneath different benefactor species. Our results indicate that native plants can have facilitative effects on invasive plants, particularly in stressful habitats such as alpine environments.

Azorellane diterpenoids from Laretia acaulis inhibit nuclear factor‐kappa B activity

Transcription factor NF-kappaB plays a key role in the inducible expression of genes mediating proinflammatory effects, and is thus an important target for the development of antiinflammatory drugs. Laretia acaulis (Cav.) Gill et Hook (Apiaceae) is a medicinal plant used in the high Andes mountains for different ailments such as diabetes, inflammation and for general pain. In addition to the known azorellanol (2) and 7-deacetylazorellanol (4), 13-epiazorellanol (1) was also isolated from the aerial part of this plant. Its structure was based on spectroscopic comparison with azorellanol (2) and by chemical characterization. While compounds 2 and 4 showed potent anti-NF-kappaB activity by targeting the activity of the IkappaBalpha kinase, compound 1 was completely inactive highlighting the importance of position 13 in the biological activities of this class of tetracyclic diterpenoids.

Microclimatic Modifications of Cushion Plants and Their Consequences for Seedling Survival of Native and Non-native Herbaceous Species in the High Andes of Central Chile

ABSTRACTCushion plants are one of the most common growth forms in alpine habitats. Their low stature, dense canopy, and compact form allow them to decouple their microclimate from the surrounding environment, mitigating the effect of low temperatures and drought, enhancing the survival of other species. In this study, we evaluated the modifications on soil temperature and moisture over an entire growing season by two cushion species (Laretia acaulis and Azorella monantha) in alpine communities located at two different elevations in the central Chilean Andes. Additionally, we performed seedling survival experiments with two native herbaceous species (Hordeum comosum and Erigeron andicola) and the non-native forb Cerastium arvense to assess if seedling survival is higher within cushions than outside them. Our results indicated that cushions ameliorated extreme low and high substrate temperatures, improved soil moisture, and enhanced seedling survival of the three herbaceous plant species evaluated. Our results suggest that microclimatic modifications associated with cushion plants could be important for the establishment and survival of other plant species, both native and non-native, in the high alpine communities of central Chile.

A Multi-species Assessment of Post-dispersal Seed Predation in the Central Chilean Andes

Post-dispersal seed predation in alpine communities has received little attention despite evidence that seeds removed by granivores can decrease plant recruitment into ecosystems. Moreover, few studies have assessed the effects of removal of seeds of a range of species after dispersal on the seeds remaining in ecosystems. A comparison was made of the magnitude of seed removal by ants and birds of nine different shrubby-, herbaceous- and cushion-plant species in the central Chilean Andes in order to assess the interactions between birds, ants and wind, and the types of seeds. A total of 324 soil-covered plates, each containing 50 seeds of one species, were placed in the field at an altitude of 2700 m and assigned to one of four treatments: control, exclusion of ants, birds, and both. The design also allowed the effects of wind to be assessed. Seed removal from plates was monitored over 20 d. Mean accumulative seed removal by granivores averaged over all nine species combined was 25%. However, large differences between species were evident, with limited seed removal (3-11%) in three herbaceous species (Alstroemeria pallida, Sisyrinchium arenarium, Pozoa coriacea), moderate (18-33%) in five species, including a shrub (Chuquiraga oppositifolia), two herbs (Taraxacum officinale, Rhodophiala rhodolirion), and two cushion-plants (Laretia acaulis, Azorella monantha), and substantial (78%) in the shrub Anarthrophyllum cumingii. The magnitudes of losses caused by birds compared with ants did not differ for the majority of species, although removal by birds was greater than by ants in A. cumingii, and smaller for C. oppositifolia. Post-dispersal seed removal is shown to be an important cause of decreased potential plant species recruitment into alpine ecosystems. The substantial differences in the magnitude of seed losses to ants and birds demonstrate the need for evaluation of seed removal on a wide range of species in any given ecosystem.

Positive interactions between alpine plant species and the nurse cushion plant Laretia acaulis do not increase with elevation in the Andes of central Chile

In alpine habitats, positive interactions among plants tend to increase with elevation as a result of altitudinal increase in environmental harshness. However, in mountains located in arid zones, lower elevations are also stressful because of scarce availability of water, suggesting that positive interactions may not necessarily increase with elevation. Here we analysed the spatial association of plant species with the nurse cushion plant Laretia acaulis at two contrasting elevations, and monitored the survival of seedlings of two species experimentally planted within and outside cushions in the semiarid Andes of central Chile. Positive spatial associations with cushions were more frequent at lower elevations. Species growing at the two elevations changed the nature of their association with cushions from neutral or negative at higher elevations to positive at lower elevations. Survival of seedlings was higher within cushions, particularly at lower elevations. The increased facilitation by cushions at lower elevations seems to be related to provision of moisture. This result suggests that cushion plants play a critical role in structuring alpine plant communities at lower elevations, and that climatic changes in rainfall could be very relevant for persistence of plant communities.

Pharmaco-toxicological study of diterpenoids

Azorella compacta, Azorella yareta and Laretia acaulis (Apiaceae) are native species from the high Andes Mountains, northeastern Chile, and they have being traditionally used to treat asthma, colds and bronchitis, illnesses with inflammation and pain as the main symptoms. Interestingly, there are no scientific reports available on their benefits or toxicity. This study was carried out with the purpose of validating the medicinal use of these species and to discover anti-inflammatory and analgesic new molecules. As a working hypothesis, we have proposed that these medicinal species contain bioactive compounds with anti-inflammatory and analgesic effects. In this context, azorellanol, 13-hydroxy-7-oxoazorellane and 7-deacetylazorellanol, three diterpenoids previously isolated only from these plants, were subjected to farmaco-toxicological evaluation. Their topical anti-inflammatory and analgesic activities along with acute toxicities or innocuosness were also investigated. Our results indicate the absence of toxic and side effects in mice. All compounds presented dose-related inhibition of pain. 13-hydroxy-7-oxoazorellane was the most potent analgesic but it was less effective than sodium naproxen, the reference drug. Azorellanol exhibited the highest topical anti-inflammatory potency on AA (arachidonic acid) and TPA (12-deoxyphorbol 13-tetradecanoate) induced oedema, and it effect was similar to the reference drugs (nimesulide and indomethacin). Probably, its mechanism of action could be explained through the inhibition to cyclo-oxygenase activity. Our results corroborate the anti-inflammatory and analgesic effects of these species, and it justifies their use in folk medicine.

Interactions in the patterns of vegetative growth and reproduction in woody dioecious plants.

Interactions between vegetative growth and reproduction were evaluated in Peumus boldus, Lithraea caustica and Laretia acaulis, three woody dioecious species in central Chile. Phenological observations were made periodically on marked branches of male and female plants, and biomass allocation (dry weight) to vegetative and reproductive tissues was measured. The magnitude of flowering was evaluated in groups of plants in three successive seasons. The patterns of activities are species- and sex-dependent, and cycles of 2-4 years have been established. Branches that produce flowers either do not grow or grow less than branches without flowers, and males and females have differential resource allocation: male branches attain higher biomass values. Groups of plants show seasonal behavior that suggest synchrony in their reproductive activities.

Laretia Acaulis, a Cushion Plant of the Andes: Ethnobotanical Aspects and the Impact of Its Harvesting

Ethnobotanical aspects of the utilization of Laretia acaulis, a cushion plant of the high Andes, as well as ecological consequences of its harvesting were analysed in Santiago, and in La Parva (to the east of Santiago, at 2,700 m a.s.l.), Chile, between 1979 and 1981. The plant is used mostly by the lower income group for the treatment of several diseases. Family tradition and lack of better jobs are determinant factors in the activity of herb-collectors and vendors. Although collectors are selective, in some places the amount harvested surpasses the regeneration capacity of L. acaulis. Considerable loss of soil and fragmentation of cushions are also detectable. Some conservation measures are suggested. RtSUMt Laretia acaulis, une plante-coussinet des Andes: Les aspects ethnobotaniques et I'impact de sa recolte. Les aspects ethnobotaniques de l'utilisation de Laretia acaulis, une plante-coussinet des hautes Andes, ainsi que les consequences de sa recolte ont ete etudiees a Santiago et a La Parva (a 'est de Santiago, a 2700 m d'altitude), Chili, entre 1979 et 1981. Cette plante est principalement utilisee par les couches les plus pauvres de la population pour le traitement de divers maladies. La tradition familiale et 'absence de meilleurs emplois sont les facteurs determinants de la cueillette et de la vente des herbes. Bien que la cueillette soit selective, la quantite recoltee surpasse la capacite de regeneration de L. acaulis. Des pertes de sol considerables et une fragmentation des coussinets ont egalement pu etre constatees. Quelques mesures de conservation sont proposees. ZUSAMMENFASSUNG Laretia acaulis, eine Polsterpflanze der Anden: Ethnobotanische Aspekte und der Einfluss des Pfluckens. Von 1979-1981 wurden in Santiago und La Parva (ostlich von Santiago auf 2700 m) Chile, ethnobotanische Aspekte der Nutzung von Laretia acaulis, einer Polsterpflanze der Hochanden und ihrer oekologischen Konsequenzen untersucht. Die Pflanze wird vor allem von der minderbemittelten Bevolkerungsschicht fur die Behandlung verschiedener Krankheiten genutzt. Familientradition und das Fehlen besserer Arbeit sind die ausschlaggebenden Faktoren fur die Tatigkeit des Krautersammlers und -verkaufers. Obschon die Sammler selektiv vorgehen, iibersteight die Erntemenge die Regenerationsfaihigkeit der L. acaulis an einigen Stellen. Betrachtlicher Bodenverlust und die Zerstuckelung der Polsterpflanzen sind nachgewiesen. Einige Konservierungsmassnahmen werden suggeriert.