Plant Biostimulants from Cyanobacteria: An Emerging Strategy to Improve Yields and Sustainability in Agriculture

Abstract

Cyanobacteria can be considered a promising source for the development of new biostimulants as they are known to produce a variety of biologically active molecules that can positively affect plant growth, nutrient use efficiency, qualitative traits of the final product, and increase plant tolerance to abiotic stresses. Moreover, the cultivation of cyanobacteria in controlled and confined systems, along with their metabolic plasticity, provides the possibility to improve and standardize composition and effects on plants of derived biostimulant extracts or hydrolysates, which is one of the most critical aspects in the production of commercial biostimulants. Faced with these opportunities, research on biostimulant properties of cyanobacteria has undergone a significant growth in recent years. However, research in this field is still scarce, especially as regards the number of investigated cyanobacterial species. Future research should focus on reducing the costs of cyanobacterial biomass production and plant treatment and on identifying the molecules that mediate the biostimulant effects in order to optimize their content and stability in the final product. Furthermore, the extension of agronomic trials to a wider number of plant species, different application doses, and environmental conditions would allow the development of tailored microbial biostimulants, thus facilitating the diffusion of these products among farmers.

Reciprocal Garden Study Reveals Acute Spatial-Edaphic Adaptation for Cycas micronesica

“…Only the local coralloid roots were applied in each garden, and 15 mL of the slurry was buried in each hole. Applying cyanobacteria or extracts from cyanobacteria to the base of plants is a common form of exploiting the benefits of cyanobacteria for plant health [25]. The north garden site consisted of shallow cobbly clay loams that formed in sediments that overlie coralline limestone (clayey, gibbsitic, nonacid, isohyperthermic, Lithic Ustorthents) [26].…”

“…Only the local coralloid roots were applied in each garden, and 15 mL of the slurry was buried in each hole. Applying cyanobacteria or extracts from cyanobacteria to the base of plants is a common form of exploiting the benefits of cyanobacteria for plant health [25].…”

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

“…Recently, cyanobacteria have gained considerable attention as beneficial bioagents based on their ability to produce biomass for biofertilizers to be used in sustainable farming [18,50,118]. These organisms have been considered beneficial to soil fertility and crops through their ability to fix atmospheric nitrogen solubilize phosphate [119], produce bioactive substances, such as hormones (auxins, gibberellins, cytokinins) [120], polypeptides, amino acids [121], polysaccharides [122], and siderophores [123], having stimulatory effects on plants.…”

“…As reported by the Scopus ® database (Figure 1b), scientific reports on cyanobacteria primarily cover the agricultural and biological sciences topic area, although some topic areas may overlap. More specifically, most articles refer to the biostimulant effect, as these microorganisms are a source of macro-and micronutrients, bioactive molecules, and plant hormones that may positively influence the plant [18]. More recently, only a few dozen articles referring to the effect of cyanobacteria on plant pathogens were cited in the Scopus database (search for "cyanobacteria + versus + plant pathogens").…”

Enriched root bacterial microbiome in invaded vs native ranges of the model grass allotetraploid Brachypodium hybridum

“…The Cyanobacteria could be affecting B. hybridum growth in the invaded range through fixation of dinitrogen or through the substances it produces. A recent literature review by Santini et al (2021), found that Cyanobacteria are rich in auxin and auxin-like compounds, which act as biostimulants in plants. These biostimulants result in increased root mass and elongation and increased plant nutrient uptake.…”