Phytochemical Variations and Enhanced Efficiency of Antioxidant and Antimicrobial Ingredients in Salvia officinalis as Inoculated with Different Rhizobacteria

Abstract

Plants produce a variety of secondary metabolites to improve their performance upon exposure to pathogens, pests, herbivores, or environmental stresses. Secondary metabolism in plants is, therefore, highly regulated by presence of biotic or abiotic elicitors in the environment. The present research was undertaken to characterize plant growth-promoting attributes of four plant growth-promoting rhizobacteria (PGPR) including two Pseudomonas fluorescens (Pf Ap1, Pf Ap18) and two P. putida (Pp Ap9, Pp Ap14) strains, and to determine their role (individually or in consortium) on growth of Salvia officialis, and biosynthesis of secondary metabolites such as essential oils (EOs), total phenolics, and flavonoids. The antioxidant and antibacterial properties of the extracts and EOs obtained from the inoculated plants were also investigated. The PGPR inoculum was applied to soil, cuttings, and foliage. Results indicated that different PGPR strains varied in their efficiency for production of auxin, siderophore, 1-aminocyclopropane-1-carboxylate deaminase, and phosphate solubilization. All individually inoculated plants had significantly higher shoot and root biomass, leaf P content, EOs yield, total phenolics, and flavonoids content compared to uninoculated control plants. The major constituents of EOs, cis-thujene, camphor, and 1,8-cineol, increased following inoculation with reference PGPRs. Although the extract from all inoculated plants had improved antioxidant activity, it was remarkable for the Pf Ap18 strain, which had the lowest IC50 value across treatments. Antibacterial assay of various EOs and their major constituents against pathogenic bacteria showed that the highest activity was observed against Staphylococcus aureus using EOs of Pp Ap14 source. Based on our findings, we suggest that individual inoculation with effective PGPR strains can substantially improve plant growth and secondary metabolism in S. officinalis plants.

Physiological and biochemical changes in Matricaria chamomilla induced by Pseudomonas fluorescens and water deficit stress

“…They altogether give details why the plants inoculated with the fluorescent pseudomonads synthesis much more amount of essential oils compared to non-inoculated plants especially under water deficit stress condition (Figure 2). Thus, biological elicitors which are also found in P. fluorescens can be used for inducing synthesis of secondary metabolites especially in medicinal plants (Ghorbanpour et al, 2016). …”

Development of waterborne polyurethane-ureas added with plant extracts: Study of different incorporation routes and their influence on particle size, thermal, mechanical and antibacterial properties

“…Examples include Salvia officinalis L. (Lamiaceae family), commonly known as sage and traditionally used in culinary and medicinal preparations [14], whose chemical composition is associated with effective antibacterial, antioxidant and anti-inflammatory properties [14,15]. Salvia officinalis is characterized by presenting mainly terpenoids (such as αand β-thujone, camphor and 1,8-cineole), and a polyphenolic fraction which includes phenolic acids (rosmarinic, ferulic and caffeic acid), flavonoids (luteolin, apigenin and naringenin) and diterpenes (carnosic acid, carnosol, rosmanol, epirosmanol and isorosmanol) [16,17].…”

Plant Metabolites in Plant Defense Against Pathogens

“…For example, heavy metals such as Al 3+ ,Cr 3+ ,Co 2+ ,Ni 2+ , Table 2. Effect of biotic elicitor on the production of various secondary metabolites in plants [54][55][56][57][58][59][60][61][62][63][64].…”