Phytochemical diversity of the metabolite profiles relates to the biostimulatory potential of agriculturally beneficial cyanobacteria

Abstract

Cyanobacteria interact with biota, including higher plants, through the secretion of metabolites, which provide nutrition or elicit immunity, thereby establishing beneficial linkages. However, the phytochemical diversity, in relation to their plant-growth promoting and biofertilizing roles is less understood. Towards this endeavour, the metabolite profiles of three cyanobacterial cultures-Anabaena laxa (C11), Nostoc carneum (BF2), and Anabaena doliolum (BF4)-were evaluated. Biochemical attributes were analysed at 14 and 21 DAI (Days After Inoculation), followed by untargeted GC-MS (Gas Chromatography-Mass Spectrometry) analyses of the metabolite profiles at 21 DAI. Partial Least Squares Discriminant Analysis (PLS-DA), supported by Volcano plot and Correlation network analyses, were employed to highlight the key metabolites. Partial Least Squares Discriminant Analysis (PLS-DA), supported by Volcano plot and Correlation network analyses, illustrated the predominance of organic compounds, in particular, sugars, amino acids and their conjugates, illustrating the significance of C-N metabolism in all the cultures. The metabolites were also rich in response molecules to environmental stressors and a multiplicity of bioactive molecules (particularly glyceryl glycoside, glycerol, lactose, sucrose, and glutamic acid). A. laxa yielded the most hits across several chemical classes, including sugars, organic compounds, amino acids, and nucleotides. Comparison with previously documented metabolite profiles highlighted the differential relative abundance of these compounds, representative of the core metabolome of these agriculturally-significant cyanobacteria. This phytochemical-analysis guided investigation provided insights into the biostimulatory role of cyanobacterial metabolites in nutritional and signalling mechanisms, underscoring their significance as biological options for boosting crop growth and soil fertility.

Keywords: Amino acids; IAA; Organics; Plant growth; Sugars.