Hidden diversity in forest soils: Characterization and comparison of terrestrial flatworm’s communities in two national parks in Spain

Terrestrial flatworms (Platyhelminthes, Tricladida, and Geoplanidae) belong to what is known as cryptic soil fauna of humid forests and are animals not easily found or captured in traps. Nonetheless, they have been demonstrated to be good indicators of the conservation status of their habitat as well as a good model to reconstruct the recent and old events affecting biodiversity. This is mainly due to their delicate constitution, their dependence on the integrity of their habitat, and their very low dispersal capacity. At present, little is known about their communities, except for some studies performed in Brazil. In this work, we analyze for the first time in Europe terrestrial flatworm communities. We have selected two protected areas belonging to the Red Española de Parques Nacionales. Our aims include performing a first study of the species richness and community structure for European terrestrial planarian species at regional and local scale. We evaluate the effect of type of forests in the community composition and flatworms’ abundance, but also have into account the phylogenetic framework (never considered in previous studies) analyzed based on molecular data. We find differences in the species composition among parks, with an astonishingly high diversity of endemic species in the Parque Nacional de Picos de Europa and an extremely low diversity of species in the Parque Nacional de Ordesa y Monte Perdido. These divergent patterns cannot be attributed to differences in physical variables, and in addition, the analyses of their phylogenetic relationships and, for a few species, their genetic structure, point to a more probable historical explanation.     

Salt tolerance of two perennial grass <Emphasis Type="Italic">Brachypodium sylvaticum</Emphasis> accessions

Key message

We studied the salt stress tolerance of two accessions isolated from different areas of the world (Norway and Tunisia) and characterized the mechanism(s) regulating salt stress in Brachypodium sylvaticum Osl1 and Ain1.

Abstract

Perennial grasses are widely grown in different parts of the world as an important feedstock for renewable energy. Their perennial nature that reduces management practices and use of energy and agrochemicals give these biomass crops advantages when dealing with modern agriculture challenges such as soil erosion, increase in salinized marginal lands and the runoff of nutrients. Brachypodium sylvaticum is a perennial grass that was recently suggested as a suitable model for the study of biomass plant production and renewable energy. However, its plasticity to abiotic stress is not yet clear. We studied the salt stress tolerance of two accessions isolated from different areas of the world and characterized the mechanism(s) regulating salt stress in B. sylvaticum Osl1, originated from Oslo, Norway and Ain1, originated from Ain-Durham, Tunisia. Osl1 limited sodium transport from root to shoot, maintaining a better K/Na homeostasis and preventing toxicity damage in the shoot. This was accompanied by higher expression of HKT8 and SOS1 transporters in Osl1 as compared to Ain1. In addition, Osl1 salt tolerance was accompanied by higher abundance of the vacuolar proton pump pyrophosphatase and Na⁺/H⁺ antiporters (NHXs) leading to a better vacuolar pH homeostasis, efficient compartmentation of Na⁺ in the root vacuoles and salt tolerance. Although preliminary, our results further support previous results highlighting the role of Na⁺ transport systems in plant salt tolerance. The identification of salt tolerant and sensitive B. sylvaticum accessions can provide an experimental system for the study of the mechanisms and regulatory networks associated with stress tolerance in perennials grass.

     

Effect of cement industry flue gas simulation on the physiology and photosynthetic performance of <Emphasis Type="Italic">Chlorella sorokiniana</Emphasis>

Cement plants account for significant emissions of CO₂ and other pollutants into the atmosphere. As a means for its mitigation, we tested the effect of a cement industry-based flue gas simulation (FGS — 18% CO₂, 9% O₂, 300 ppm NO₂, 140 ppm SO₂) on the green alga, Chlorella sorokiniana. Culture pH, cell density, cell viability and productivity, specific growth rates, photosynthetic performance, and biochemical composition were monitored. The treatments consisted of different FGS volumes (0.1, 0.3, 0.8, 1.5, 6, and 48 L day^?1) that were applied in a series of laboratory-scale semi-continuous batch cultures under controlled conditions. Controls were exposed to 18% CO₂ enriched air. Cell density showed that C. sorokiniana was able to grow in all treatments, but compared to the controls, low pH (~ 5.0) caused by 48 L FGS day^?1 led to 27% decrease in specific growth rate. Increasing FGS exposure decreased maximum and operational quantum yields obtained by pulse amplitude modulated fluorometry, while photochemical quenching remained constant (~ 0.93). The α and rETR _max parameters calculated from rapid light curves decreased with increasing FGS exposure. Total proteins and carbohydrates (per cell basis) increased after 6 and 48 L FGS day^?1, which can be advantageous for biotechnological applications, but cell productivity (cells L^?1 day^?1) decreased. Despite the effects in physiology, C. sorokiniana could withstand a pH range of 6.0–5.0 imposed by 48 L FGS day^?1. Overall, C. sorokiniana can be considered a robust species in flue gas bioremediation.     

<Emphasis Type="Italic">NmEXT</Emphasis> Extensin Gene: a Positive Regulator of Resistance Response Against the Oomycete <Emphasis Type="Italic">Phytophthora nicotianae</Emphasis>

The oomycete pathogens produce important diseases in many plant species. To identify extensin genes expressed during the oomycete Phytophthora nicotianae-Nicotiana megalosiphon interaction, we used the SuperSAGE technology. Using this approach, we detected a N. megalosiphon extensin gene (NmEXT) triggered during the interaction. The extensin gene accumulation induced by the pathogen correlated with disease resistance in different Nicotiana species. Transient expression of NmEXT gene in susceptible Nicotiana tabacum enhanced the resistance to P. nicotianae. Our date indicated that NmEXT gene served a positive role in N. tabacum resistance against P. nicotianae.     

Territory size as a main driver of male-mating success in an Amazonian nurse frog (<Emphasis Type="Italic">Allobates paleovarzensis</Emphasis>, Dendrobatoidea)

In polygamous mating systems, it is most often males that compete for the opposite sex, using strategies to provide access to as many females as possible. Females, on the other hand, constitute the sex that exerts the choice and so require a means of accessing the quality of a potential partner in comparison to its competitors. A common challenge in sexual selection studies is to identify the most relevant trait for mating success, since many are correlated with each other. In addition, little is known about how the female accesses the aspects related to male quality. In this context, we tested the role of different male characteristics on mating success in a natural environment using the Amazonian frog Allobates paleovarzensis as a model. A multiple linear regression model showed a positive relationship between territory size and number of male matings, while calling persistence was slightly related to the mating success. We did not detect a relation of the number of matings with the distance to the nearest body of water nor with male body size. Additionally, we observed that territory size was not related to calling persistence, but had a positive relation with the duration of the couple’s courting process. Thus, we conclude that: (1) territory size is the main determinant of male-mating success, and this is not correlated with the other attributes tested; and (2) females access the size of the males’ territory through the courting process that precedes oviposition.     

Diversity of fungal latent pathogens and true endophytes associated with fruit trees in Uruguay

We have explored the fungal diversity in asymptomatic twigs of apple, peach, pear and blueberry trees, with the objective of discerning between true endophytes and latent pathogens. Several fungal genera containing known bark pathogens were found. Seven Diaporthe species—D. oxe, D. infecunda, D. serafiniae, D. phaseolorum, D. terebinthifolii, D. foeniculina and D. brasiliensis—were identified, along with Botryosphaeria dothidea, Neofusicoccum parvum, Neofusicoccum australe, Cytospora sp., Cytospora acaciae and Pestalotiopsis spp. A pathogenicity trial was undertaken to determine the role of these species on apple, pear, blueberry and peach shoots. Diaporthe brasiliensis, D. foeniculina, Diaporthe inconspicua, D. terebinthifolii, Diaporthe sp.1, Cytospora‐like isolates and Pestalotiopsis spp. isolates produced no lesions on inoculated shoots, suggesting that they could be considered true endophytes on their respective hosts. Meanwhile, some of the isolates of Diaporthe—D. oxe, Diaporthe sp.2, D. infecunda and D. serafiniae, B. dothidea, N. parvum and N. australe could be regarded as latent pathogens in their respective hosts as they produced sunken cankers and necrosis on inoculated shoots. These results demonstrate that apple, pear, blueberry and peach healthy shoots can host many known endophytic fungi along with potential wood disease‐causing fungi that should be regarded as latent pathogens.     

The Value of Forests to World Food Security

We assembled information on the contribution and value of forests to world food security. An assessment was made of the role of forests and non-timber products in the food system of developing countries. We estimated that upwards of 300 million people annually earn part or all of their livelihood and food from forests. A total of about $90 billion in non-timber products are harvested each year. Forests also help to protect land, water, and biological resources, and they play an important role in maintaining the productivity of agricultural and environmental systems.     

Melatonin and the phagocytic process of heterophils from the ring dove (Streptopelia risoria)

A functional connection between the pineal gland and the immune system in mammals and birds has been established. This study investigates the effect of melatonin upon the non-specific immunity of heterophils isolated from the ring dove. The different stages of the phagocytic process: adherence to nylon fiber, spontaneous and induced mobility, ingestion of latex beads and digestion were evaluated for heterophils incubated in the presence of 5, 25, 50, 75, or 100 \sgmaelig;M of melatonin. In addition, the chemoattractant power of the hormone for heterophils was studied. The 100 \sgmaelig;M melatonin dose possessed a significant chemoattractant ability for heterophils whilst ingestion of latex particles was enhanced at all doses studied. The superoxide anion level, as measured by the free radicals produced during the metabolic burst, is decreased after incubation with 100 \sgmaelig;M of melatonin.