Exploring Pavlova pinguis chemical diversity: a potentially novel source of high value compounds

To uncover the potential of Pavlova pinguis J.C. Green as a natural source of value added compounds, its lipophilic extracts were studied before and after alkaline hydrolysis using gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis of the lipophilic extracts showed a wide chemical diversity including 72 compounds distributed by fatty acids (29), sterols (14), fatty alcohols (13) and other lipophilic compounds (16). Fatty acids represented the main class of identified compounds presenting myristic, palmitic, palmitoleic and eicosapentaenoic acids as its main components. Through the ∑ω6/∑ω3 ratio (0.25) and sterol composition it was possible to observe that P. pinguis is a valuable source of ω3 fatty acids and stigmasterol (up to 43% of total sterols). After alkaline hydrolysis, fatty acids and fatty alcohols content increased by 32 and 14% respectively, in contrast to, monoglycerides which decreased by 84%. The long chain alcohols content enables the exploitation of this microalga as a source of these bioactive compounds. Smaller amounts of sugars and other compounds were also detected. The present study is a valuable reference to the metabolite characterization of P. pinguis and shows the potential of this microalga for nutraceutical and pharmaceutical industries.info:eu-repo/semantics/publishedVersio

Cyanobacteria: A Natural Source for Controlling Agricultural Plant Diseases Caused by Fungi and Oomycetes and Improving Plant Growth

Cyanobacteria, also called blue-green algae, are a group of prokaryotic microorganisms largely distributed in both terrestrial and aquatic environments. They produce a wide range of bioactive compounds that are mostly used in cosmetics, animal feed and human food, nutraceutical and pharmaceutical industries, and the production of biofuels. Nowadays, the research concerning the use of cyanobacteria in agriculture has pointed out their potential as biofertilizers and as a source of bioactive compounds, such as phycobiliproteins, for plant pathogen control and as inducers of plant systemic resistance. The use of alternative products in place of synthetic ones for plant disease control is also encouraged by European Directive 2009/128/EC. The present up-to-date review gives an overall view of the recent results on the use of cyanobacteria for both their bioprotective effect against fungal and oomycete phytopathogens and their plant biostimulant properties. We highlight the need for considering several factors for a proper and sustainable management of agricultural crops, ranging from the mechanisms by which cyanobacteria reduce plant diseases and modulate plant resistance to the enhancement of plant growth

Different Antifungal Activity of <i>Anabaena</i> sp., <i>Ecklonia</i> sp., and <i>Jania</i> sp. against <i>Botrytis cinerea</i>

Water extracts and polysaccharides from Anabaena sp., Ecklonia sp., and Jania sp. were tested for their activity against the fungal plant pathogen Botrytis cinerea. Water extracts at 2.5, 5.0, and 10.0 mg/mL inhibited B. cinerea growth in vitro. Antifungal activity of polysaccharides obtained by N-cetylpyridinium bromide precipitation in water extracts was evaluated in vitro and in vitro at 0.5, 2.0, and 3.5 mg/mL. These concentrations were tested against fungal colony growth, spore germination, colony forming units (CFUs), CFU growth, and on strawberry fruits against B. cinerea infection with pre- and post-harvest application. In in vitro experiments, polysaccharides from Anabaena sp. and from Ecklonia sp. inhibited B. cinerea colony growth, CFUs, and CFU growth, while those extracted from Jania sp. reduced only the pathogen spore germination. In in vitro experiments, all concentrations of polysaccharides from Anabaena sp., Ecklonia sp., and Jania sp. reduced both the strawberry fruits infected area and the pathogen sporulation in the pre-harvest treatment, suggesting that they might be good candidates as preventive products in crop protection

Preliminary Study on the Activity of Phycobiliproteins against Botrytis cinerea

Phycobiliproteins (PBPs) are proteins of cyanobacteria and some algae such as rhodophytes. They have antimicrobial, antiviral, antitumor, antioxidative, and anti-inflammatory activity at the human level, but there is a lack of knowledge on their antifungal activity against plant pathogens. We studied the activity of PBPs extracted from Arthrospira platensis and Hydropuntia cornea against Botrytis cinerea, one of the most important worldwide plant-pathogenic fungi. PBPs were characterized by using FT-IR and FT-Raman in order to investigate their structures. Their spectra differed in therelative composition in the amide bands, which were particularly strong in A. platensis. PBP activity was tested on tomato fruits against gray mold disease, fungal growth, and spore germination at different concentrations (0.3, 0.6, 1.2, 2.4, and 4.8 mg/mL). Both PBPs reduced fruit gray mold disease. A linear dose\u2013response relationship was observed for both PBPs against disease incidence and H. cornea against disease severity. Pathogen mycelial growth and spore germination were reduced significantly by both PBPs. In conclusion, PBPs have the potential for being also considered as natural compounds for the control of fungal plant pathogens in sustainable agriculture

Prospecting algae and cyanobacteria as bioprotectans for plant disease control

The European Directive 2009/128 on sustainable use of pesticides promotes the use of alternative approaches to synthetic products for plant disease control to reduce human, animals and environmental risks. Among alternatives, natural products based on cyanobacteria and algae are gaining attention. Our studies demonstrated that application of water extracts from Anabaena minutissima, Ecklonia maxima and Jania adhaerens controlled powdery mildew caused by Podosphaera xanthii on cucumber detached cotyledons and seedlings and induced the expression of PR genes related to plant-induced resistance. In addition, tomato seed treatment with the same extracts increased germination, seedling dry weight, calibre, and reduced root rot caused by Rhizoctonia solani on tomato plants. Seed treatment also increased chitinase activity and lignin compound contents in tomato seedlings. A deeper investigation on the possible bioactive compounds of A. minutissima, E. maxima and J. adhaerens, revealed the antifungal activity of polysaccharides against Botrytis cinerea, agent of grey mould, in vitro and in vivo on strawberry fruits. Latest research pointed out that application of phycobiliproteins from A. minutissima, Arthrospira platensis and Hydropuntia cornea on tomato fruits before B. cinerea challenge reduced grey mould disease. In particular, FT-IR and FT-Raman spectroscopies have shown that phycobiliproteins from A. minutissima preserved cutin and pectine structures of tomato fruit from B. cinerea infection. In conclusion, our research demonstrate the potentialities of algae and cyanobacteria as a bioprotectans for plant disease control

Assessing the Potential of the Terrestrial Cyanobacterium Anabaena minutissima for Controlling Botrytis cinerea on Tomato Fruits

Cyanobacteria are oxygenic phototrophs that have an essential role in soil N2 fixation, fertility, and water retention. Cyanobacteria are also natural sources of bioactive metabolites beneficial to improve plant vigor and potentially active against fungal plant pathogens. Therefore, we studied the antifungal activity of water extract (WE) and phycobiliproteins (PBPs) from Anabaena minutissima strain BEA 0300B against the fungal plant pathogen Botrytis cinerea on tomato fruits and in vitro. The water extract and PBPs were characterized by using FT-IR and FT-Raman spectroscopies. Both water extract (5 mg/mL) and PBPs (ranged from 0.3 to 4.8 mg/mL) reduced disease incidence and disease severity on tomato fruits and mycelium growth and colony forming units in vitro. For mycelium growth, a linear PBP dose-response was found. Tomato fruits were also characterized by FT-IR and FT-Raman spectroscopies in order to evaluate structural modifications induced by pathogen and PBP treatment. PBPs preserved cutin and pectin structures by pathogen challenge. In conclusion, A. minutissima can be considered a potential tool for future large-scale experiments for plant disease control

Tomato seed biopriming with water extracts from Anabaena minutissima,Ecklonia maxima and Jania adhaerens as a new agro-ecological option against Rhizoctonia solani

In recent years, the use of synthetic pesticides in agriculture has been restricted for environmental pollution issues. Alternatives to chemicals for plant disease control are highly recommended by the recent EU legislation. We tested tomato seed treatment with water extracts from Anabaena minutissima, Ecklonia maxima, and Jania adhaerens for their biocontrol activity against the fungal plant pathogen Rhizoctonia solani. Algae were characterized into their contents in macro and microelements and into their functional groups by using FT-IR spectroscopy. The extracts were applied at 0.0, 2.5, 5.0, and 10.0 mg/mL concentrations on tomato seeds against the pathogen, in in vitro experiments and under greenhouse conditions. To estimate the efficiency of treatment in priming plant defence response, plant chitinase activity was measured and the different distribution of functional groups of roots was determined by FT-IR spectroscopy. Increases of germination and seedling dry weight for treated seeds without pathogen challenge were observed. The extracts reduced disease severity and increased seedling dry weight both in in vitro and greenhouse experiments at all concentrations. All extracts also increased stem seedling calibre under greenhouse conditions. The plant chitinase activity was increased by all extracts. The aromatic rings assigned to lignin changed with the treatment. We concluded that, although our experiments were based on a small scale, algae and cyanobacteria water extracts could provide a potential tool for the R. solani control on tomato plants, by contributing to the reduction of synthetic product input in the environmen

Barrancaceae: A new green algal lineage with structural and behavioral adaptations to a fluctuating environment

PREMISE OF THE STUDY: To enhance our knowledge of the diversity of microalgae, a phycological survey of the Canary Islands (Spain) was undertaken. Here we report the discovery of a (semi)terrestrial green filamentous alga isolated from a steep volcanic canyon on La Palma. This alga is continually exposed to changing weather conditions (floods vs.droughts) and thus provides a good opportunity to investigate possible adaptations to a semiterrestrial habitat with large fluctuations of environmental parameters. METHODS: We used axenic cultures, simulated flood and drought stresses and studied their effect on the life history of the alga using light, confocal laser scanning and scanning electron microscopy including fluorescent staining. Furthermore, phylogenetic analyses using rDNA sequence comparisons were performed. KEY RESULTS: Three specific life-history traits that likely represent adaptations to the fluctuating environment of the canyon were observed: (1) fragmentation through filament splitting, a unique branching mechanism not reported before in algae and initiated by formation of oblique cross walls, (2) apla-nospore formation, and (3) reproduction by multiflagellate zoospores with 4-24 flagella arranged in groups of four. Phylogenetic analyses identified the alga as Barranca multiflagellata gen.et sp.nov. (Barrancaceae fam.nov., Chaetophorales, Chlorophyceae). Moreover, the Chaetophoraceae Greville, 1824 was emended and a new family, Uronemataceae (fam.nov.) erected. CONCLUSIONS: The discovery of Barrancaceae fam.nov. highlights the importance of investigating nonconventional habitats to explore microalgal diversity. The reproductive versatility demonstrated by Barranca suggests adaptation to a semiterrestrial habitat with large fluctuations in water availability