Female and male fitness of a sexually deceptive orchid with a narrow distribution area: from phenotypic traits to spatial distribution patterns

• The Orchidaceae family presents one of the most extravagant pollination mechanisms: deception. While many studies on reproductive success have been performed on food‐deception orchids, less have been performed on sexually deceptive orchids. Here, we focused on Ophrys balearica P. Delforge, an endemic orchid of the Balearic Islands, to study its reproductive ecology, the spatio‐temporal variation of its reproductive success and the individual (floral display and geospatial position) and population parameters (patch size, shape and density) that affect its reproductive success.
• We performed hand‐pollination experiments, along with the recording of floral display parameters and GPS position of over 1,100 individuals from seven populations in two consecutive years. We applied, for the first time, GIS tools to analyse the effects of individual’s position within the population on the reproductive success. Reproductive success was measured both in male (removed pollinia) and female (fruit set) fitness.
• The results confirm that this species is pollinator‐dependent and mostly allogamous, but also self‐compatible. This species showed high values for the cumulative inbreeding depression index and high pollen limitation. Male fitness was almost equal to female fitness between years and populations, and reproductive success exhibited huge spatio‐temporal variation.
• Although we did not find strong correlations between floral display and reproductive success, patches with low‐plant density and individuals in the external portion of the population showed significantly higher plant fitness. These findings must be considered in conservation actions for endangered orchid species, especially considering that most orchids are strongly dependent on pollinators for their species’ fitness.

     

Nutritional interaction in an alga-barnacle association

Nitrogen is the major growth-limiting nutrient for marine algae. One potential source of nitrogen for marine algae is ammonium released by invertebrates. Many mid-intertidal reefs in northeastern New Zealand are dominated by a close association between the honeycomb barnacle Chamaesipho columna and an encusting brown alga Pseudolithoderma sp. Growth of Pseudolithoderma was enhanced in the presence of live C. columna, which released ammonium at a greater rate than the maximum rate of ammonium uptake by Pseudolithoderma. Algal tissue on barnacle tests had a lower C:N ratio than tissue located more than 2 cm from the nearest barnacle, suggesting the barnacle is an important source of nitrogen for the alga. The role of nutrient exchange in determining ecological patterns of species in marine communities is discussed.     

The lre-miR159a-LrGAMYB pathway mediates resistance to grey mould infection in Lilium regale

Grey mould is one of the most determinative factors of lily growth and plays a major role in limiting lily productivity. MicroRNA159 (miR159) is a highly conserved microRNA in plants, and participates in the regulation of plant development and stress responses. Our previous studies revealed that lre-miR159a participates in the response of Lilium regale to Botrytis elliptica according to deep sequencing analyses; however, the response mechanism remains unknown. Here, lre-miR159a and its target LrGAMYB gene were isolated from L. regale. Transgenic Arabidopsis overexpressing lre-MIR159a exhibited larger leaves and smaller necrotic spots on inoculation with Botrytis than those of wild-type and overexpressing LrGAMYB plants. The lre-MIR159a overexpression also led to repressed expression of two targets of miR159, AtMYB33 and AtMYB65, and enhanced accumulation of hormone-related genes, including AtPR1, AtPR2, AtNPR1, AtPDF1.2, and AtLOX for both the jasmonic acid and salicylic acid pathways. Moreover, lower levels of H₂O₂ and were observed in lre-MIR159a transgenic Arabidopsis, which reduced the damage from reactive oxygen species accumulation. Taken together, these results indicate that lre-miR159a positively regulates resistance to grey mould by repressing the expression of its target LrGAMYB gene and activating a defence response.     

Binding and Functional Folding (BFF): A Physiological Framework for Studying Biomolecular Interactions and Allostery

EF-hand Ca²⁺-binding proteins (CBPs), such as S100 proteins (S100s) and calmodulin (CaM), are signaling proteins that undergo conformational changes upon increasing intracellular Ca²⁺. Upon binding Ca²⁺, S100 proteins and CaM interact with protein targets and induce important biological responses. The Ca²⁺-binding affinity of CaM and most S100s in the absence of target is weak (^CaK_D > 1 μM). However, upon effector protein binding, the Ca²⁺ affinity of these proteins increases via heterotropic allostery (^CaK_D < 1 μM). Because of the high number and micromolar concentrations of EF-hand CBPs in a cell, at any given time, allostery is required physiologically, allowing for (i) proper Ca²⁺ homeostasis and (ii) strict maintenance of Ca²⁺-signaling within a narrow dynamic range of free Ca²⁺ ion concentrations, [Ca²⁺]^free. In this review, mechanisms of allostery are coalesced into an empirical “binding and functional folding (BFF)” physiological framework. At the molecular level, folding (F), binding and folding (BF), and BFF events include all atoms in the biomolecular complex under study. The BFF framework is introduced with two straightforward BFF types for proteins (type 1, concerted; type 2, stepwise) and considers how homologous and nonhomologous amino acid residues of CBPs and their effector protein(s) evolved to provide allosteric tightening of Ca²⁺ and simultaneously determine how specific and relatively promiscuous CBP-target complexes form as both are needed for proper cellular function.     

Effects of Peanut Genotypes on Meloidogyne Species Interactions

A 3-year microplot study was conducted to characterize the interaction between Meloidogyne arenaria race 1 (MA1) and M. hapla (MH), as affected by the five peanut genotypes: Florigiant, NC 7, NC 6, NC Ac 18416, and NC Ac 18016. The interactive effects on infection (total parasitic forms per root unit) and reproduction potentials of each nematode species and crop damage were determined. As a single population, MA1 had greater infection capacity and caused more crop damage than did MH, but both species had similar reproduction potentials. In mixed infestations, MA1 was more competitive than MH, as reflected by incidence of infection. Infection and reproduction potentials, and crop-damage capabilities of the mixed populations were similar to those of MA1 alone. All peanut genotypes were susceptible to infection by both nematodes. NC 6 was less susceptible to damage by MA1 and the mixed populations than other genotypes. A nematode treatment x genotype interaction was detected for root infection and crop damage, but not for population density or reproduction. With high preplant nematode levels (Pi), the populations reached their peak by midseason, whereas those with low Pi peaked after midseason. Crop damage in the second and third years was correlated with Pi level.     

Membrane–drug interactions studied using model membrane systems

The direct interaction of drugs with the cell membrane is often neglected when drug effects are studied. Systematic investigations are hindered by the complexity of the natural membrane and model membrane systems can offer a useful alternative. Here some examples are reviewed of how model membrane architectures including vesicles, Langmuir monolayers and solid supported membranes can be used to investigate the effects of drug molecules on the membrane structure, and how these interactions can translate into effects on embedded membrane proteins.