Ranunculus Acris Research Articles

Self-incompatibility in Ranunculus acris L

Apparent fundamental differences between monocot and dicot incompatibility systems raised the question whether these systems had developed independently, or whether they had a common origin. The incompatibility system in the dicot Ranunculus acris was examined because the family, Ranunculaceae, presumably has an evolutionary basis in common with the monocots. Studies in F1-families have shown that at least three multiallelic S-loci govern the incompatibility system. Further, complementary interaction between loci must be assumed in that all S-genes of the haploid pollen have to be matched in the pistil to cause incompatibility. These assumptions were confirmed by F2-families, which also showed that the S-loci imprint pollen gametophytically. The system found in R. acris differs from the systems normally found in the dicots, but is in agreement with the incompatibility system found in the monocot family Gramineae, although the latter system seems to be governed by only two S-loci. Evolutionary aspects are discussed, and essential questions which are still to be answered, are mentioned.

Self-incompatibility in Ranunculus acris

The present case of P(S)C investigated in Ranunculus acris L. was shown to be closely correlated with a certain S-allele, but otherwise obviously a quantitative character, controlled in the style. Pseudo-compatibility (PC) exceeds pseudo-self-compatibility (PSC), phenomena that are regarded as an effect of the same failure in the function of the incompatibility mechanism. P(S)C in individuals obtained through PC further exceeds that of individuals obtained through PSC and the PSC-degree decreases by inbreeding. No definite hypothesis as to the cause of P(S)C in this species is proposed, but the correspondence with other systems is discussed. It should be remembered that R. acris has an incompatibility system with gametophytic pollen control, performed by at least four co-operating S-loci.

Self-incompatibility in Ranunculus acris L.

Apparent fundamental differences between monocot and dicot incompatibility systems raised the question whether these systems had developed independently, or whether they had a common origin. The incompatibility system in the dicot Ranunculus acris was examined because the family, Ranunculaceae, presumably has an evolutionary basis in common with the monocots. Studies in F1-families have shown that at least three multiallelic S-loci govern the incompatibility system. Further, complementary interaction between loci must be assumed in that all S-genes of the haploid pollen have to be matched in the pistil to cause incompatibility. These assumptions were confirmed by F2-families, which also showed that the S-loci imprint pollen gametophytically. The system found in R. acris differs from the systems normally found in the dicots, but is in agreement with the incompatibility system found in the monocot family Gramineae, although the latter system seems to be governed by only two S-loci. Evolutionary aspects are discussed, and essential questions which are still to be answered, are mentioned.

Application of micronucleus assay in plants to monitor environmental pollution in situ

Samples of 5 vascular plant species: Achillea millefolium L., Artemisia vulgaris L., Festuca gigantea (L.) VILL., Ranunculus acris L. s. str. and Vicia angustifolia L. were collected near Fuel Storage Station, Chemical Fibre Factory “Wistom” in Tomaszów Mazowiecki and Sewage Treatment Plant in Sulejów. Genotoxicity of environmental pollution was analysed using micronucleus assays in pollen mother and root tip cells in comparison with plant material collected in the Tatra and Babia G óra National Parks. Abnorm alities in morphology of plants growing in polluted areas were also found. The cytogenetical analyses revealed positive correlation between the percentage of micronuclei and the presence of heavy metals in soil. Pollen mother cells (germ line) were found more susceptible to DNA damage as compared with root tip cells (somatic line).

The potential use of ascospores as the active ingredient for aSclerotinia sclerotiorum-based mycoherbicide

A Sclerotinia sclerotiorum-based mycoherbicide has shown potential in previous studies for control of Ranunculus acris in New Zealand dairy pastures. Historically, mycelium has been used to inoculate wheat grains, which are then milled and broadcast onto the R. acris-infested pasture. Since ascospores are responsible for most infections under natural conditions, this inoculum type may be more pathogenic than mycelium and, therefore, better suited than mycelium as the active ingredient of a mycoherbicide. To test this hypothesis, two screening studies were conducted on detached R. acris leaves: one to determine an appropriate nutrient amendment for ascospore infection and another to determine the effect of leaf wounding on ascospore infection. The ascospores infected detached, wounded leaves when amended either with distilled water or inorganic phosphate (KH2PO4 or Pi)+5.5mM glucose but they infected intact leaves only when amended with Pi+5.5mM glucose. Subsequently, an experiment using detached leaves was conducted (1) to compare infection by mycelium and ascospores of intact leaf tissue and (2) to determine an ascospore concentration that produced equivalent infection to that of the mycelial inoculum. Only the highest ascospore concentration (2.5 ×106 ascospores/mL) gave similar infection to a 5-mm mycelial plug from 8 days after inoculation onwards and no infection was observed with ascospore concentrations below 2.5×103 ascospores/mL. Results fromthis research indicate that ascospores have potential as the active ingredient for the mycoherbicide and should be further investigated in whole plant experiments.

Influence of storage method on the viability, mycelial growth and pathogenicity ofSclerotinia sclerotiorumsclerotia

The effect of three storage methods on the viability, mycelial growth and pathogenicity of Sclerotinia sclerotiorum (isolate S36) sclerotia was determined with a view towards establishing an optimal method for storing this pathogen during its mass production as a mycoherbicide for controlling the weed Ranunculus acris. Sclerotia were stored at −80°C, 4°C after desiccation, or at room temperature after freeze-drying and their germination, growth and pathogenicity were assessed after 6, 12, 18, 24 and 30 months in these conditions. Germination was maintained at 100% at −80°C and when dry-stored at 4C. In contrast, freeze-dried sclerotia showed a significant reduction in germination and insufficient mycelium was produced at 30 months for growth and pathogenicity assessments. Colony growth from the stored sclerotia was similar for all three storage methods and durations. Pathogenicity, assessed using the leaves of R. acris, was the same for all three storage methods. This study indicates that the sclerotia of S. sclerotiorum may be successfully stored either at −80°Cor at4°C after desiccation for use as a mycoherbicide, but that freeze-drying is not a suitable method.

A review of the ecology and management of Ranunculus acris subsp. acris in pasture

Summary Ranunculus acris subsp. acris is widespread in pastures across Europe. In New Zealand, it persists in dairy pastures throughout the country, despite the annual use of herbicides, causing a loss in the national yield of milk solids estimated at NZ$156 million in the 2001–2002 milking season. Its persistence appears to be due in part to the production of a blistering agent, protoanemonin, which deters grazing animals, combined with evolved resistance to herbicides and a resilience imparted by a stout rhizome supporting dormant axillary buds. The latter enables regeneration after damage inflicted by herbicides, fungi and other control agents, and facilitates lateral spread and asexual reproduction. Its persistence in dairy pastures may also be influenced by plants recruiting from seeds which are formed annually subject to the availability of insect pollinators. Based on a review of observations and experiments conducted mainly in Europe and New Zealand, we propose a detailed life‐cycle model for R. acris. This provides the basis for a matrix population model that will identify the life‐cycle stages that contribute most to population growth and, hence, the extent to which each of these would need to be targeted for improved management in dairy pastures in New Zealand.

Differential effects of flower feeding in an insect host–parasitoid system

Abstract In many insect host–parasitoid systems, both the host and its parasitoids forage on shared floral resources. As a result of insect behaviour, morphology and physiology, flower species may act selectively at different levels of such systems, e.g., between the trophic levels of hosts and parasitoids, between species within a guild, between sexes or individuals within a species or between life history traits within an individual. We asked if effects of selectivity are consistent across levels in the horse chestnut leafminer, Cameraria ohridella , and its parasitoid complex. Insects were exposed singly in no-choice feeding trials to twelve common flower species and their survival and reproduction were recorded. Only one of twelve flower species ( Ranunculus acris ) tended to selectively favour the longevity of leafminers, but not of parasitoids. No flower species were found to favour parasitoids only. Both trophic levels profited from feeding on Anthriscus sylvestris , however, parasitoids benefited up to eight times more than their hosts. No differences were found among the species of the parasitoid guild, but females lived significantly longer than males, and single individuals within species were able to exploit generally unfavourable flower species. Out of the seven flower species that increased the longevity of leafminer females, only Chaerophyllum hirsutum significantly enhanced the number of eggs laid. Fecundity was generally positively correlated with longevity of leafminer females, but two flower species ( C. hirsutum , Taraxacum officinale ) had an additional positive effect on fecundity. In conclusion, we demonstrated that flowers act differently on life history traits in a host–parasitoid system at a multitude of biological levels and that these effects are not always consistent across levels. Selective plant-derived resources can therefore modify herbivore–natural enemy interactions in ways that are more complex than currently appreciated.

Mycorrhizal benefit in two low arctic herbs increases with increasing temperature

Climate change may influence the relationship between arctic plants and their symbiotic mycorrhizal fungi. The benefit of the symbiosis for the host plant affects vegetation succession and may be a key parameter in predicting vegetation responses to warming. We investigated the mycorrhizal benefit in the low arctic perennial herbs Potentilla crantzii and Ranunculus acris in symbiosis with the arbuscular mycorrhizal fungus Glomus claroideum. Temperature response in the mycorrhiza-mediated acquisition of nitrogen (N) and phosphorus (P), growth, and photosynthetic nutrient-use efficiency were determined. Near the average natural soil temperature (12°C), mycorrhiza did not improve plant nutrient capture but significantly enhanced plant P capture at 17°C. Photosynthetic nitrogen-use efficiency was higher at 17°C than at 12°C and was further increased by mycorrhiza at 17°C. Photosynthetic phosphorus-use efficiency was not affected by temperature or mycorrhiza. Increasing the growing temperature by 5°C increased the relative shoot growth rate by 15%. Mycorrhizal symbiosis did not enhance plant growth rate, but the plants gained between 20% and 90% more mycorrhiza-mediated P when grown at higher temperature. The results suggest that these low arctic species have good potential to respond positively to increasing temperatures.

Pollen limitation affects progeny vigour and subsequent recruitment in the insect‐pollinated herb Ranunculus acris

Pollen limitation on seed production appears to be widespread among the angiosperms. However, few studies have examined if pollen limitation affects population growth. We supplementally hand‐pollinated all flowers of 20 individuals of Ranunculus acris in the temperate meadow Rudsviki, Kaupanger, west Norway in 2003. The seed production did not respond to pollen addition, but the achene weight increased by 18% after supplemental pollination. To test whether this progeny quality response to the pollen‐supplementation experiment could contribute to population growth, we sowed achenes from hand‐pollinated plants and control plants into natural conditions in ten blocks at three densities. During the subsequent season (2004), the number of seedlings and juveniles (pooled) from hand‐pollinated plants were substantially (64%) higher than from controls. There was also a clear positive effect of seed sowing‐density on recruitment, suggesting that recruitment is seed‐limited in this system. However, the density of vegetative individuals in 2005 was generally low and did not differ significantly between plots that received achenes from control or supplementary pollinated plants. Our results show that pollen limitation may affect germination through seed quality, and thereby impact plant population dynamics. However, in our system it appears that other factors, such as intra‐ and interspecific competition, may have outweighed the potential contribution from pollen limitation on population demography.

Pollen limitation affects progeny vigour and subsequent recruitment in the insect-pollinated herb Ranunculus acris

Pollen limitation affects progeny vigour and subsequent recruitment in the insect-pollinated herb Ranunculus acris

Winners and losers in herbaceous plant communities: insights from foliar carbon isotope composition in monocultures and mixtures

Summary We established monocultures and 16 unique mixed communities of 12 native grasses, legumes and non‐N2‐fixing forbs. We identified species having a greater or lesser yield in the mixed communities than expected from monoculture data as winners and losers, respectively. To test our hypothesis that performance of the subordinate species (losers) is mainly controlled by light availability, whereas the dominant species (winners) are sensitive to the availability of below‐ground resources, we traced the effects of number of species, light transmission in the community and foliar N concentration on plant photosynthesis through leaf C isotope composition (δ13C). Phalaris arundinacea and Phleum pratense, the two tallest grass species, yielded more in mixtures than expected, as, initially, did Dactylis glomerata. Festuca ovina, the smallest grass, and Ranunculus acris, a forb, had smaller yield in mixtures than expected. For most species, observed mixture yields did not deviate significantly from those expected. Decreases in transmitted light decreased δ13C in D. glomerata, Lotus corniculatus and Rumex acetosa. The δ13C of Trifolium pratense and L. corniculatus was affected by increasing number of species in the plant community even after accounting for the transmitted light. In P. arundinacea, δ13C increased with increasing foliar %N, as expected for the tallest, dominant species. Species showing a positive, significant relationship between δ13C and transmitted light were relatively low growing and unable to establish dominance in multispecies communities due to shading by larger dominants. We conclude that above‐ground competition is crucial in determining C isotope composition among the subordinate species, whereas the dominant species are more strongly affected by below‐ground resources. Different factors thus dictate the physiological performance of species according to the size‐distribution hierarchy in the community.

Stone Age settlements at S�r�ya, sub-arctic Norway: impact on the vegetation

Four pollen diagrams, which together cover the period 10400 cal bp to the present, from an area rich in Stone Age house foundations show that vegetation was increasingly influenced by man in a stepwise process. There was a modest, temporary appearance of anthropogenically-induced vegetation about 8600 cal bp. After 7100 cal bp there was a development towards semi-open birch woodland where the open patches were characterised by natural heath and meadow species and more typical apophytic taxa such as Ranunculus acris and Rumex acetosa types, grasses and juniper. The main changes towards this vegetation seem connected with the most important cultural changes, especially at about 7100 cal bp, when there was a transition to honed slate tools in the regional archaeology, at about 4000 cal bp when pottery was introduced, and at about 3000–2800 cal bp since when the use of stone artefacts gradually ceased. It is suggested that the settlements were mainly summer habitations.

Evaluation of <i>Sclerotinia sclerotiorum</i> for giant buttercup control in dairy pastures

An experiment was established in November 2002 on each of two dairy farms in Golden Bay (East Takaka and Pupu Valley) to evaluate a myceliumonwheat formulation of the fungus Sclerotinia sclerotiorum as a mycoherbicide against giant buttercup (Ranunculus acris) Granules were applied to individual giant buttercup plants or manually broadcast onto infested pasture at 500 kg/ha The mortality of the giant buttercup plants reached 63 at East Takaka compared with 13 at Pupu Valley Survivors were stunted so that the mean size of a treated plant was 27 and 56 of that of untreated plants 100 days after treatment at the East Takaka and Pupu Valley sites respectively These effects remained evident 12 months after application A second experiment confirmed these results

No evidence for a role of pollinator discrimination in causing selection on flower size through female reproduction

The preference for certain floral phenotypes by flower visiting animals may fuel the evolution of floral traits because variation in flower visitation rates may lead to fitness variation within a population. Here, I examine the importance of flower size for pollinator visitation rate, seed set, and seed mass in two alpine populations of the insect‐pollinated herb Ranunculus acris L. during two seasons. There was no pollen limitation of seed set or mass. Pollinators discriminated strongly against flowers experimentally reduced in size. Despite this, there were no signs of any significant impact of flower size on female reproductive success. The results show that although pollinators discriminate strongly among floral phenotypes, this may not always result in female fitness differences within a population because seed set or mass is not limited by pollen availability alone. Probably abiotic environmental constraints prevent plants with high pollinator visitation from capitalizing on the high pollen deposition.

Dairy production revenue losses in New Zealand due to giant buttercup (Ranunculus acris)

Giant buttercup (Ranunculus acris L.), a species of European origin, is widespread throughout New Zealand, and is an intractable weed of dairy pastures in parts of the south Auckland, Hawke's Bay, and Taranaki regions and in the districts of Southern Wairarapa, Horowhenua, and Tasman. In this study, the seasonal progression of the weed's ground cover in dairy pastures in the Tasman District was measured during 1989–90 and used, in conjunction with monthly weed‐free pasture dry matter production values, to estimate the annual percentage loss in pasture production due to a typical infestation of the weed subjected to typical control measures. Extrapolation to other infested regions and districts provided a national estimate of milk solids revenue loss due to giant buttercup in New Zealand dairy pastures of $156 million in the 2001–02 season.

Biochemical properties and enzymic capacities of chromoplasts isolated from wild buttercup ( Ranunculus acris L.)

Chromoplasts were extracted from the perianth of the wild Meadow Buttercup ( Ranunculus acris L.) and purified by sucrose density gradient centrifugation. Analysis of marker enzymes indicated that chromoplast preparations were essentially free of contamination by cytosol, mitochondria and microbodies. The distribution and recovery of glycolytic enzymes indicated an incomplete sequence of enzymes for this pathway in chromoplasts. Fructose 1, 6- bisphosphate aldolase (aldolase) was the only glycolytic enzyme for which unequivocal evidence of localisation within chromoplast preparations could not be obtained. Sub-cellular fractionation and immunological studies using antibodies raised against spinach cytosolic and chloroplastic aldolase, revealed that over 40% of its activity was associated with a washed particulate/membrane fraction in chromoplasts, but this could be removed with 1.2 M NaCl. It is concluded that Ranunculus chromoplasts do not possess a plastidial form of aldolase, and that the aldolase measured in the plastid fraction is a cytosolic form associating with plastid membranes. Isolated buttercup chromoplasts possess a functional oxidative pentose-phosphate pathway (OPPP) which could be monitored as 14CO 2 release following incubation with [U- 14C]-glucose 6-phosphate (Glc6P). 14CO 2 was not evolved when [U- 14C]-glucose 1-phosphate (Glc1P) was supplied to chromoplasts suggesting this compound is not transported into the intact organelle and that no interconversion of hexose-phosphate by phosphoglucomutase occurred outside the plastid. Transport experiments using native chromoplast vesicles preloaded with inorganic orthophosphate indicated that these organelles transported Glc6P and dihydroxyacetone phosphate (DHAP), but not Glc1P. The chromoplasts isolated from this wild plant have similar enzymic components and transport properties to other chromoplasts studied to date.

Use of sheep grazing in the restoration of semi‐natural meadows in northern Finland

Abstract. The biodiversity of species‐rich semi‐natural meadows is declining across Europe due to ceased management. In this study we aimed to find out how successfully the local species richness of an overgrown semi‐natural mesic meadow could be restored by sheep grazing after a long period of abandonment. The cover of vascular plant species in grazed plots and ungrazed exclosures was studied for five years and the responses of different functional plant groups were followed (herbs vs grasses, tall vs short species, species differing in flowering time, species representing different Grime's CSR strategies and species indicative of rich vs poor soil). Grazing increased species number by nearly 30%. On grazed plots the litter cover practically disappeared, favouring small herbs such as Rhinanthus minor, Ranunculus acris, Trifolium pratense and the grass Agrostis capillaris. Grazing decreased the cover of the late flowering tall herb Epilobium angustifolium but had no effect on the abundance of the early flowering tall herbs Anthriscus sylvestris or Geranium sylvaticum. We suggest that to succeed in restoration it is useful to determine the responses of different functional plant groups to grazing. Grassland managers need this information to optimize the methods and timing of management used in restoration. Additional management practices, such as mowing, may be needed in mesic meadows to decrease the dominance of tall species. The availability of propagules seemed to restrict further increase of species richness in our study area.

Vegetation of uncultivated arable land under different management in Finnish and Russian Karelia

The vegetation of uncultivated arable land under modern, cereal/forage cropping in Finnish Karelia ( n=10) and old fashioned hay cultivation in Russian Karelia ( n=10) was compared in terms of their species composition. The plots ( n=160) were located in field margins, fallow fields and non-intensively used or abandoned hay fields unploughed over the last five years. In the TWINSPAN classification, the Finnish and Russian sites ended up in their own groups, with the exception of two sites. The mean numbers of taxa were only slightly higher in Russia, but there were major differences in species composition. According to indicator species analysis, the Finnish sites were characterised by species of early successional stages and nutrient rich, abandoned fields, such as Epilobium angustifolium, Sonchus arvensis, Elymus repens, Anthriscus sylvestris and Tussilago farfara. The Russian sites were characterised by species adapted to more stable conditions ( Ranunculus acris, Luzula multiflora), cultivated species ( Dactylis glomerata, Alopecurus pratensis) and species benefiting from hay cultivation ( Leucanthemum vulgare, Galium album). The number and cover of monocotyledon species, sedges in particular, was higher in Russia, the cover of perennial weeds being higher in Finland.

Estimating economic losses due to pasture weeds

A method is presented for estimating the economic loss sustained by a pastoral industry due to a nonpalatable herbaceous weed The method requires monthly estimates of weed ground cover and dry matter produced by noninfested pasture along with the per annum production revenue and an estimate of the percentage of the industrys pastureland infested by the weed Applied to giant buttercup (Ranunculus acris L) in dairy pastures in New Zealand the method estimated the national economic loss due to this weed to be NZ 118 million in the 19992000 year