Effects of beneficial root pseudomonas on morphological, physiological, and phytochemical characteristics of Satureja hortensis (Lamiaceae) under water stress

Abstract

Water stress is the most important environmental factor that limits plant growth and yield. However, plant growth-promoting rhizobacteria (PGPR) can stimulate resistance of the plant host in unsuitable environmental conditions such as water stress. In order to evaluate whether PGPR improve morphological, physiological, and phytochemical traits of the savory plant Satureja hortensis L., the effects of two PGPR strains of Pseudomonas fluorescens Migula (PF-135 and PF-108) under two water conditions (well-watered and 50 % field capacity) were studied by performing a factorial experiment based on randomized complete block design with three replications under commercial greenhouse. The highest values of root and shoot dry matter, root length, plant height, leaf number, and branch number were observed in PF-135-inoculated plants under well-watered conditions, whereas the abovementioned parameters were found to be the lowest in noninoculated plants under water stress condition. Chlorophyll a, b, total chlorophyll, and carotenoid contents significantly changed under water stress conditions. The H 2 O 2 and MDA contents of root and shoot significantly decreased in plants inoculated with PF-135, whereas their contents increased in non-inoculated plants under water stress condition. The highest shoot oil yield was observed in plants inoculated with PF-135 under water stress condition, while the lowest shoot oil yield was observed in plants inoculated with PF-108 under well-watered condition. Twenty-eight components were found in the essential oils of S. hortensis. Carvacrol (56.81-78.15 %), c-terpinene (9.08-22.87 %), and p-cymene (5.78-14.28 %) were identified as the major components in all treatments. Plants under water stress conditions showed the highest yield of these components when inoculated with bacteria. Thus, we could suggest that the promising strains of P. fluorescens are able to minimize the deleterious effects of water stress on plant growth and improve the morphological and physiological traits of plants as well as increase the essential oil yield and quality.

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

“…Mohammadi et al (2017) reported that inoculation of Satureja hortensis L. with P. fluorescens (PF-135) not only significantly increased the plant biomass and essential oil yields under water deficit stress condition but also improved the activity of antioxidant enzymes and synthesis of proline. Moreover, an investigation on corn inoculated with Pseudomonas spp.…”

“…The PGPR strains then were evaluated based on their ability to increase chamomile seedling growth index in a sand culture assay (data are not shown). Based on the results of this assay, the Pseudomonas fluorescens-135 (PF-135) was determined as the best pseudomonads strain (Mohammadi et al, 2017). Plant growth promoting activities of this strain are shown in Table 1. )…”

PGPR‐mediated induction of systemic resistance and physiochemical alterations in plants against the pathogens: Current perspectives

“…Peanut plants treated with halotolerant bacteria such as Klebsiella, Pseudomonas, Agrobacterium, and Ochrobactrum showed an increase in nitrogen (N 2 ) content up to 76% as compared to untreated peanut plants under salinity [112]. Water stress is the most important abiotic stress, which limits the plant growth and their yield, and can be controlled by PGPR that reduces the water stress by stimulating resistance of the host [113]. Plant under the water-stressed condition showed a reduction in the activity of ascorbate peroxidase (APX) and guaiacol peroxidase (GPX), but PGPR-associated water-stressed plants showed higher activity of GPX and APX, significantly [114,115].…”

“…Water stress is the most important abiotic stress, which limits the plant growth and their yield, and can be controlled by PGPR that reduces the water stress by stimulating resistance of the host [113]. Plant under the water‐stressed condition showed a reduction in the activity of ascorbate peroxidase (APX) and guaiacol peroxidase (GPX), but PGPR‐associated water‐stressed plants showed higher activity of GPX and APX, significantly [114,115].…”

Humic Substances and Efficient Microorganisms: Elicitation of Medicinal Plants—A Review

“…Besides, microorganisms can act as elicitors and increase the production of secondary metabolites involved in the biological and pharmaceutical activity of medicinal plants (Mohammadi et al, 2017), such as flavonoids and terpenes content, phenolic compounds, microbial activity, chlorophyll content, nutrient uptake, plant growth and development (Banchio et al, 2008;Cappellari et al, 2013;Zhao et al, 2016;Damam et al, 2016;Swamy et al, 2016).…”