Histochemical observations in Piper malgassicum (Piperaceae) with a special focus on the epidermis

This is the first contribution about the histochemistry of vegetative and reproductive aerial organs in the genus Piper L. Piper malgassicum accumulates alkaloids and terpenes in the epidermis and the underlying layers of parenchyma, both in the leaves, in the stems and in anthers. Some idioblasts appear to contain a large amount of secondary metabolites. The micro-anatomical analysis showed peculiar secretory structures both in the leaves, in the anthers and in the ovary. Several lipid aggregates, alkaloid droplets and calcium oxalate crystals were observed in leaves and stems, indicating their role in defence strategies, mechanical support, and pollinators attraction. In the anthers, we observed elaioplasts whose content suggest an alternative and indirect function in pollination and defence against micro-organisms. Besides, some lipid aggregates surrounded by microtubules, detected in the anthers, were recognized as lipotubuloids. The tapetum was of secretory type. Alkaloids and terpenes were widely distributed in the plant confirming the important biological role of this type of biomolecules and its functional range. In the anthers, terpene and polyphenol inclusions appeared particularly abundant in the epidermal layer, whereas calcium oxalate crystals were observed close to the ovule in the ovary at maturity

Endophytic Bacteria Associated with Origanum heracleoticum L. (Lamiaceae) Seeds

Seed-associated microbiota are believed to play a crucial role in seed germination, seedling establishment, and plant growth and fitness stimulation, due to the vertical transmission of a core microbiota from seeds to the next generations. It might be hypothesized that medicinal and aromatic plants could use the seeds as vectors to vertically transfer beneficial endophytes, providing plants with metabolic pathways that could influence phytochemicals production. Here, we investigated the localization, the structure and the composition of the bacterial endophytic population that resides in Origanum heracleoticum L. seeds. Endocellular bacteria, surrounded by a wall, were localized close to the aleurone layer when using light and transmission electron microscopy. From surface-sterilized seeds, cultivable endophytes were isolated and characterized through RAPD analysis and 16S RNA gene sequencing, which revealed the existence of a high degree of biodiversity at the strain level and the predominance of the genus Pseudomonas. Most of the isolates grew in the presence of six selected antibiotics and were able to inhibit the growth of clinical and environmental strains that belong to the Burkholderia cepacia complex. The endophytes production of antimicrobial compounds could suggest their involvement in plant secondary metabolites production and might pave the way to endophytes exploitation in the pharmaceutical field

Potential European Emissions Trajectories within the Global Carbon Budget

The Paris Agreement, ratified in 2015, pledged to reduce greenhouse gas emissions within a Global Carbon Budget that limits the global temperature increase to less than 2 °C. With the Roadmap 2050 mitigation measures, the European Union has a target to reduce emissions by 80% of their 1990 value by 2050 but without giving an estimation or a maximum ceiling for the total amount of cumulative greenhouse gases emissions over that period. Thus, the impact of the EU regulations on global warming remains unestimated. The aim and the novelty of this study are to develop a set of potential European emissions trajectories, within the Global Carbon Budget and at the same time satisfying the Roadmap 2050 goals. The result of the study highlights the urgency to reinforce mitigation measures for Europe as soon as possible because any delay in policy implementation risks the Roadmap 2050 mitigation package being insufficient to achieve the objectives of the Paris treaty