Role of marine macroalgae in plant protection & improvement for sustainable agriculture technology

Marine macroalgae are plant-like organisms with simple internal structures that generally live in coastal areas. They mainly include different communities of red, brown and green macroalgae. Marine macroalgae commonly occupy intertidal and sublittoral-to-littoral zones on rocks and other hard substrata. They are considered to be an excellent natural biosource in different aspects of agricultural fields. They have great proficiency in improving soil physical and chemical properties. Marine macroalgae are also characterized by producing a large array of biologically active biocidal substances against plant-infecting pathogens. Unfortunately, most available literatures on marine macroalgae and their derivatives mainly focused on their pharmaceutical applications but their potential utilization in sustainable agriculture development is still often regarded as a secondary goal. However, a relatively considerable dataset on marine macroalgae showed that they could play a major role in plant protection and improvement. This review summarizes different aspects of potential macroalgal applications in agriculture. Commercial production and exploitation of specific compounds with interesting biotechnological importance from marine macroalgae including microbicides, nematicides, insecticides, biofertilizers, biostimulators and soil conditioners are highlighted and discussed in detail. Bioactive compounds like fatty acids (in particular polyunsaturated fatty acids (PUFAs), proteins (amino acids), bioflavonoids, sulfated polysaccharides, carotenoids, polyphenols and carbohydrates are considered to have bactericidal, antiviral and fungicidal effects against some plant-infecting pathogens. These biocontrol agents provide multiple benefits and act as useful pointers for improving cultivation practices in diverse habitats. Marine macroalgae can be generally considered as promising multifunctional bioinoculants and ecofriendly environmental tools in recent trends of organic farming

Toxicity of mercuric oxide nanoparticles on freshwater microalgae : comprehensive analysis on their interactive effects and detoxification pathways

Abstract: So far, there is limited research on the potential risks and environmental consequences of mercuric oxide nanoparticles (HgO-NPs) on phytoplankton. To this end, we investigated the moderate and acute concentrations of HgO-NPs (0.8 and 1.6 mg/L, respectively) on the growth, photosynthesis, and detoxification processes in two microalgae, namely Scenedesmus obliquus and Nostoc muscorum. Compared to N. muscorum, S. obliquus had greater accumulation and removal efficiencies of HgO-NPs (92.8 %, 91.4 %) at moderate and acute levels. HgONPs accumulation inhibited the growth and decreased photosynthesis, RuBisCo activity and chlorophyll a content in a dose-dependent manner. At oxidative damage level, acute level of HgO-NPs evoked severe lipid and protein peroxidation, and increased NADPH oxidase activity particularly in N. muscorum. Exposure to HgO-NPs also resulted in distinct metabolic perturbations in both microalgal species. Notably, there was a dose-dependent increase in the activity of antioxidant enzymes (e.g., peroxidase and superoxide dismutase), as well as metabolites like tocopherols and flavonoids in S. obliquus. However, the activity of catalase, ascorbate peroxidase and dehydroascorbate reductase enzymes, and ascorbate levels were significantly increased in N. muscorum. At HgONPs detoxification level, S. obliquus increased glutathione level and glutathione-S-transferases activity. However, N. muscorum showed high levels of metal chelator (phytochelatins and metalothionine). Investigating the HgONPs bioremediation capacity and stress tolerance mechanisms opens possibilities to introduce S. obliquus as a promising bioremediator to relieve ecological risk of HgO-NPs