Application of Bioactive Coatings Based on Chitosan and Propolis for Pinus spp. Protection against Fusarium circinatum

Spatiotemporal modeling of the potential impact of climate change on shifts in bioclimatic zones in Morocco

This study aims to contribute to the understanding of the impact of climate change on bioclimatic zones in Morocco, providing insights into potential shifts and emphasizing the need for adaptation measures to protect vulnerable species and ecosystems. To achieve this, we utilized eight general circulation models (GCMs) to simulate climate conditions under two representative concentration scenarios (RCP4.5 and RCP8.5) for two future time points (2050 and 2070). The modeling of bioclimatic zone shifts was accomplished through the implementation of the random forest (RF) algorithm. Our findings indicate that the subhumid and humid areas are expected to experience the most significant shifts, particularly toward the semi-arid zone. Shifts from subhumid to semi-arid were the most pronounced, ranging from 17.91% (RCP8.5 in 2070) to 25.68% (RCP8.5 in 2050), while shifts from humid to semi-arid ranged from 10.16% (RCP4.5 in 2050) to 22.27% (RCP8.5 in 2070). The Saharan and arid zones are expected to be the least affected, with less than 1% and 11% of their original extent expected to change, respectively. Moreover, our results suggest that forest species such as Atlas cedar and oaks are among the most vulnerable to these shifts. Overall, this study highlights the inevitability of climate change's impact on Moroccan ecosystems and provides a basis for adaptation measures, especially considering the species adapted to the bioclimatic conditions that will dominate the respective affected regions.

The Use of Carbohydrate Biopolymers in Plant Protection against Pathogenic Fungi

Fungal pathogens cause significant yield losses of many important crops worldwide. They are commonly controlled with fungicides which may have negative impact on human health and the environment. A more sustainable plant protection can be based on carbohydrate biopolymers because they are biodegradable and may act as antifungal compounds, effective elicitors or carriers of active ingredients. We reviewed recent applications of three common polysaccharides (chitosan, alginate and cellulose) to crop protection against pathogenic fungi. We distinguished treatments dedicated for seed sowing material, field applications and coating of harvested fruits and vegetables. All reviewed biopolymers were used in the three types of treatments, therefore they proved to be versatile resources for development of plant protection products. Antifungal activity of the obtained polymer formulations and coatings is often enhanced by addition of biocontrol microorganisms, preservatives, plant extracts and essential oils. Carbohydrate polymers can also be used for controlled-release of pesticides. Rapid development of nanotechnology resulted in creating new promising methods of crop protection using nanoparticles, nano-/micro-carriers and electrospun nanofibers. To summarize this review we outline advantages and disadvantages of using carbohydrate biopolymers in plant protection.

Bioactive Propolis-Silane System as Antifungal Agent in Lignocellulosic-Polymer Composites

Polymer composites with renewable lignocellulosic fillers, despite their many advantages, are susceptible to biodegradation, which is a major limitation in terms of external applications. The work uses an innovative hybrid propolis-silane modifier in order to simultaneously increase the resistance to fungal attack, as well as to ensure good interfacial adhesion of the filler-polymer matrix. Polypropylene composites with 30% pine wood content were obtained by extrusion and pressing. The samples were exposed to the fungi: white-rot fungus Coriolus versicolor, brown-rot fungus Coniophora puteana, and soft-rot fungus Chaetomium globosum for 8 weeks. Additionally, biological tests of samples that had been previously exposed to UV radiation were carried out, which allowed the determination of the influence of both factors on the surface destruction of composite materials. The X-ray diffraction, attenuated total reflectance-Fourier transform infrared spectroscopy, and mycological studies showed a significant effect of the modification of the lignocellulose filler with propolis on increasing the resistance to fungi. Such composites were characterized by no changes in the supermolecular structure and slight changes in the intensity of the bands characteristic of polysaccharides and lignin. In the case of systems containing pine wood that had not been modified with propolis, significant changes in the crystalline structure of polymer composites were noted, indicating the progress of decay processes. Moreover, the modification of the propolis-silane hybrid system wood resulted in the inhibition of photo- and biodegradation of WPC materials, as evidenced only by a slight deterioration in selected strength parameters. The applied innovative modifying system can therefore act as both an effective and ecological UV stabilizer, as well as an antifungal agent.

Studying tree response to biotic stress using a multi-disciplinary approach: The pine pitch canker case study

In an era of climate change and global trade, forests sustainability is endangered by several biotic threats. Pine pitch canker (PPC), caused by Fusarium circinatum, is one of the most important disease affecting conifers worldwide. To date, no effective control measures have been found for this disease. Earlier studies on PPC were mainly focused on the pathogen itself or on determining the levels of susceptibility of different hosts to F. circinatum infection. However, over the last years, plenty of information on the mechanisms that may explain the susceptibility or resistance to PPC has been published. This data are useful to better understand tree response to biotic stress and, most importantly, to aid the development of innovative and scientific-based disease control measures. This review gathers and discusses the main advances on PPC knowledge, especially focusing on multi-disciplinary studies investigating the response of pines with different levels of susceptibility to PPC upon infection. After an overview of the general knowledge of the disease, the importance of integrating information from physiological and Omics studies to unveil the mechanisms behind PPC susceptibility/resistance and to develop control strategies is explored. An extensive review of the main host responses to PPC was performed, including changes in water relations, signalling (ROS and hormones), primary metabolism, and defence (resin, phenolics, and PR proteins). A general picture of pine response to PPC is suggested according to the host susceptibility level and the next steps and gaps on PPC research are pointed out.

Bioplastics: Missing link in the era of Microplastics

Concerns about microplastics (MPs) environmental behavior and accumulation are growing at global scale and meanwhile, the attention to employ bioplastics for replacing conventional plastics is increasing. The research priority for a better understanding of the fate and potential impacts of MPs from bioplastics is of utmost importance. However, the investigations on the effects of bioplastics in terms of MPs are still limited and largely unknown. In this discussion, the current knowledge of MPs is timely highlighted to incorporate biodegradable MPs in the ongoing researches. Recent studies have identified that some biodegradable MPs exhibit same effect as conventional type MPs. Furthermore, we performed a simple degradation experiment and found that polyhydroxyalkanoate films formed MPs in water environment alike other biodegradable and conventional plastics sharing common research interests. In an effort to promote investigations, we recommend the knowledge gaps identified on bioplastics MPs: understanding the timeframe of disintegration and degradation of developing bioplastics; ensuring degradability and less persistence; promoting toxicity tests and potential effects on a wide variety of organisms; promoting attempts to assess the impacts on ecosystems; evaluating the interaction of microorganisms and MPs; working towards identifying novel disposal and collection methods from public to ease recycling and degradation processes.

White-Rot Fungi Control on Populus spp. Wood by Pressure Treatments with Silver Nanoparticles, Chitosan Oligomers and Propolis

There is growing interest in the development of non-toxic, natural wood preservation agents to replace conventional chemicals. In this paper, the antifungal activities of silver nanoparticles, chitosan oligomers, and propolis ethanolic extract were evaluated against white-rot fungus Trametes versicolor (L.) Lloyd, with a view to protecting Populus spp. wood. In order to create a more realistic in-service type environment, the biocidal products were assessed according to EN:113 European standard, instead of using routine in vitro antimicrobial susceptibility testing methods. Wood blocks were impregnated with the aforementioned antifungal agents by the vacuum-pressure method in an autoclave, and their biodeterioration was monitored over 16 weeks. The results showed that treatments based on silver nanoparticles, at concentrations ranging from 5 to 20 ppm, presented high antifungal activity, protecting the wood from fungal attack over time, with weight losses in the range of 8.49% to 8.94% after 16 weeks, versus 24.79% weight loss in the control (untreated) samples. This was confirmed by SEM and optical microscopy images, which showed a noticeably higher cell wall degradation in control samples than in samples treated with silver nanoparticles. On the other hand, the efficacy of the treatments based on chitosan oligomers and propolis gradually decreased over time, which would be a limiting factor for their application as wood preservatives. The nanometal-based approach is thus posed as the preferred choice for the industrial treatment of poplar wood aimed at wood-based engineering products (plywood, laminated veneer lumber, cross-laminated timber, etc.).

Biopolymeric Films of Amphiphilic Derivatives of Chitosan: A Physicochemical Characterization and Antifungal Study

The chemical modification of chitosan has been an active subject of research in order to improve the physicochemical and antifungal properties of chitosan-based films. The aim of this study was to evaluate the physiochemical and antifungal properties of films prepared with chitosan and its derivatives containing diethylaminoethyl (DEAE) and dodecyl groups (Dod). Chitosans and selected derivatives were synthesized and characterized, and their films blended with glycerol and sorbitol (5%, 10%, and 20%). They were studied by means of the evaluation of their mechanical, thermal, barrier, and antifungal properties. The collected data showed that molecular weight (Mw), degree of acetylation, and grafting with DEAE and Dod groups greatly affected the mechanical, thickness, color, and barrier properties, all of which could be tailored by the plasticizer percentage. The antifungal study against Aspergillus flavus, Alternaria alternata, Alternaria solani, and Penicillium expansum showed that the films containing DEAE and Dod groups exhibited higher antifungal activity than the non-modified chitosans. The mechanical properties of highly soluble films were improved by the plasticizers at percentages of 5% and 10%, indicating these derivatives as potential candidates for the coating of seeds, nuts and fruits of various crops.