Serratia marcescens BM1 Enhances Cadmium Stress Tolerance and Phytoremediation Potential of Soybean Through Modulation of Osmolytes, Leaf Gas Exchange, Antioxidant Machinery, and Stress-Responsive Genes Expression

Abstract

The heavy metal contamination in plant-soil environment has increased manifold recently. In order to reduce the harmful effects of metal stress in plants, the application of beneficial soil microbes is gaining much attention. In the present research, the role of Serratia marcescens BM1 in enhancing cadmium (Cd) stress tolerance and phytoremediation potential of soybean plants, was investigated. Exposure of soybean plants to two Cd doses (150 and 300 µM) significantly reduced plant growth, biomass, gas exchange attributes, nutrients uptake, antioxidant capacity, and the contents of chlorophyll, total phenolics, flavonoids, soluble sugars, and proteins. Additionally, Cd induced the stress levels of Cd, proline, glycine betaine, hydrogen peroxide, malondialdehyde, antioxidant enzymes (i.e., catalase, CAT; ascorbate peroxidase, APX; superoxide dismutase, SOD; peroxidise, POD), and the expression of stress-related genes (i.e., APX, CAT, Fe-SOD, POD, CHI, CHS, PHD2, VSO, NR, and P5CS) in soybean leaves. On the other hand, inoculation of Cd-stressed soybean plants with Serratia marcescens BM1 significantly enhanced the plant growth, biomass, gas exchange attributes, nutrients uptake, antioxidant capacity, and the contents of chlorophyll, total phenolics, flavonoids, soluble sugars, and proteins. Moreover, Serratia marcescens BM1 inoculation reduced the levels of cadmium and oxidative stress markers, but significantly induced the activities of antioxidant enzymes and the levels of osmolytes and stress-related genes expression in Cd-stressed plants. The application of 300 µM CdCl2 and Serratia marcescens triggered the highest expression levels of stress-related genes. Overall, this study suggests that inoculation of soybean plants with Serratia marcescens BM1 promotes phytoremediation potential and Cd stress tolerance by modulating the photosynthetic attributes, osmolytes biosynthesis, antioxidants machinery, and the expression of stress-related genes.

Saudi Rosmarinus officinalis and Ocimum basilicum L. Polyphenols and Biological Activities

“…R. officinalis and O. basilicum leaf extract antioxidant activities were investigated using β-carotene bleaching, ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays [5,24,[37][38][39]. Lyophilized dried leaves were powdered then extracted with methanol (0.2 g DW (dry weight) in 10 mL) by sonication twice for 30 min at 30 • C. Purification was conducted using Whatman paper, then the residues were dried at room temperature (to lose methanol).…”

Malus baccata var. gracilis and Malus toringoides Bark Polyphenol Studies and Antioxidant, Antimicrobial and Anticancer Activities

“…Bark extracts were subjected to β-carotene bleaching as well as FRAP and DPPH assays in triplicate replications [3,[57][58][59][60][61]. A wavelength of 470 nm was used in the β-carotene bleaching experiment, while a 517 nm wavelength was used in the DPPH to measure absorbance.…”

Melatonin Counteracts Drought Induced Oxidative Damage and Stimulates Growth, Productivity and Fruit Quality Properties of Tomato Plants

“…It causes several interconnected responses leading to considerable damages at morphological, physiological, biochemical, and molecular levels [ 5 , 6 , 7 , 8 , 9 ]. Among these effects, water deficit causes altering of leaf water status, hindering stomatal conductance, reducing nutrient uptake, degradation of leaf pigments and photosynthesis depression [ 9 , 10 , 11 ]. Furthermore, the rapid accumulation of reactive oxygen species (ROS) and drought induced oxidative damages have been extensively reported in many previous studies [ 12 , 13 , 14 ].…”