A Microbial-Based Biostimulant Enhances Sweet Pepper Performance by Metabolic Reprogramming of Phytohormone Profile and Secondary Metabolism

Abstract

Microbial-based biostimulants can improve crop productivity by modulating cell metabolic pathways including hormonal balance. However, little is known about the microbial-mediated molecular changes causing yield increase. The present study elucidates the metabolomic modulation occurring in pepper (Capsicum annuum L.) leaves at the vegetative and reproductive phenological stages, in response to microbial-based biostimulants. The arbuscular mycorrhizal fungi Rhizoglomus irregularis and Funneliformis mosseae, as well as Trichoderma koningii, were used in this work. The application of endophytic fungi significantly increased total fruit yield by 23.7% compared to that of untreated plants. Multivariate statistics indicated that the biostimulant treatment substantially altered the shape of the metabolic profile of pepper. Compared to the untreated control, the plants treated with microbial biostimulants presented with modified gibberellin, auxin, and cytokinin patterns. The biostimulant treatment also induced secondary metabolism and caused carotenoids, saponins, and phenolic compounds to accumulate in the plants. Differential metabolomic signatures indicated diverse and concerted biochemical responses in the plants following the colonization of their roots by beneficial microorganisms. The above findings demonstrated a clear link between microbial-mediated yield increase and a strong upregulation of hormonal and secondary metabolic pathways associated with growth stimulation and crop defense to environmental stresses.

An Endophytic Fungi-Based Biostimulant Modulates Volatile and Non-Volatile Secondary Metabolites and Yield of Greenhouse Basil (Ocimum basilicum L.) through Variable Mechanisms Dependent on Salinity Stress Level

“…This occurred despite the fact that at these thresholds the factors are considered to change “significantly”, and differences among treatments were mostly due to the presence of the inoculum and seen by a magnitude of the effect (+156% of Fe Uptake in the low stress and +53% in the high stress). In particular, AMF showed to be able to amply sustain the uptake of Fe-bound P by the plant [ 32 , 63 ] and some Trichoderma species showed to sustain P or Fe uptake by a siderophore production [ 64 , 65 , 66 , 67 ]. The role of the inoculum in the exclusion of the Na uptake in the high stress was higher than in the low stress.…”

Improvement of Soil Microbial Diversity through Sustainable Agricultural Practices and Its Evaluation by -Omics Approaches: A Perspective for the Environment, Food Quality and Human Safety

“…PHs and AMF biostimulant had positive effects on biomass, phytohormones production and improved tolerance to reactive oxygen species (ROS)-mediated oxidative imbalance. Likewise, [ 75 ] demonstrated a clear link between endophytic fungi - mediated yield increase in pepper plants and a strong up-regulation of phytohormones. Moreover, metabolomics analysis highlighted the molecular basis of the improved loquat plant growth in the presence of the root rot fungus Armillaria mellea following AMF colonization [ 116 ].…”

“…In general, plants produce natural defense substances like PSC after biotic or abiotic stress exposure, mainly depending on plant genotype, but their expression may be modulated by various different agronomic and environmental factors, including crop interaction with rhizosphere microbes [ 135 , 136 ]. For instance, the metabolomic analyses disclosed a clear link between AMF and PGPR inoculation in pepper and basil respectively, increased crops yield and the accumulation of several PSC associated with crop defense to environmental stresses [ 75 , 138 ]. Similarly, the metabolome analysis revealed that olive growing in fields where no-tillage and crop residue cover were applied, shown higher PSC concentration in xylem sap [ 139 ].…”

A Metabolomic Landscape of Maize Plants Treated With a Microbial Biostimulant Under Well-Watered and Drought Conditions

“…Omics sciences, particularly metabolomics, are emerging as indispensable approaches in decoding the mechanisms of action employed by biostimulants ( Nephali et al, 2020 ). Recent metabolomics studies have shown that a microbial biostimulant increased the yield of sweet pepper by inducing a metabolic readjustment of hormones and secondary metabolism ( Bonini et al, 2020 ). Furthermore, some of the currently elucidated molecular changes underlying microbial-induced systemic resistance against drought stress include (i) the production of phytohormones, siderophores, volatiles and osmolytes, (ii) the enhanced antioxidant defense system and (iii) 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and exopolysaccharides (EPS) production ( Ahemad and Kibret, 2014 ; Vurukonda et al, 2016 ; Prasad et al, 2017 ; Bhat et al, 2019 ).…”