Influence of the Rhizobacterium Rhodobacter sphaeroides KE149 and Biochar on Waterlogging Stress Tolerance in Glycine max L.

Abstract

In the context of the current climate change and increasing population scenarios, waterlogging stress in plants represents a global threat to sustainable agriculture production. Plant-growth-promoting rhizobacteria and biochar have been widely reported to mitigate the effects of several abiotic stresses. Hence, in the present study, we examined the effect of the rhizobacterium Rhodobacter sphaeroides KE149 and biochar on soybean plants subjected to sufficient water supply and waterlogging stress conditions. Our results revealed that KE149 and biochar inoculation significantly improved plant morphological attributes, such as root length, shoot length, and fresh biomass. The biochemical analysis results showed that the two treatments determined a significant drop in the levels of endogenous phytohormones (such as abscisic acid) under normal conditions, which were considerably enhanced under waterlogging stress. However, the jasmonic acid content increased with the application of biochar and KE149 under normal conditions, and it considerably decreased under waterlogging stress. Moreover, proline, methionine, and aspartic acid were significantly increased, whereas the phenolic and flavonoid contents were reduced with the application of the two treatments under waterlogging stress. These results suggest that the application of KE149 and biochar can be a safe biological tool with which to improve the physiology and productivity of soybean plants exposed to waterlogging stress.

The intervention of classical and molecular breeding approaches to enhance flooding stress tolerance in soybean – An review

“…It is also known as a "stress hormone" that controls numerous responses to abiotic stresses, but its role in flood tolerance leftovers many gaps (Zhao et al, 2021). Hormonal application is a well-known agronomic approach to mitigating the toxic effects of flood stress in soybean (Kang et al, 2021;Pan et al, 2021;Tamang et al, 2021;Wang and Komatsu, 2022). Tamang et al (2021) revealed that abscisic (ABA) acid and ethylene (ET) are candidate hormones that direct transcriptomic energy-saving developments under flood stress.…”

Characterization of the Pyrroloquinoline Quinone Producing Rhodopseudomonas palustris as a Plant Growth-Promoting Bacterium under Photoautotrophic and Photoheterotrophic Culture Conditions

“…There are also studies exploring the interaction between phototrophic bacteria and plants, such as their ability to produce plant-growth-promoting substances [ 49 ]. The main contributions of phototrophic bacteria to plants include aiding in nitrogen fixation, solubilizing phosphate, and increasing the content of soluble sugars and secondary metabolites [ 50 , 51 , 52 ]. Additional plant-growth-promoting mechanisms of PNSB can be explored in the comprehensive review [ 49 ].…”

From Lab to Farm: Elucidating the Beneficial Roles of Photosynthetic Bacteria in Sustainable Agriculture

“…Recently, a IAA-producing rhizobacterium R. sphaeroides KE149 was reported to be able to improve adzuki bean's morphological characteristics as well as to regulate phytohormone content under flood and drought stress [78]. In addition, co-inoculation with KE149 and biochar could help to promote plant growth and strengthen the antioxidant system of soybean plant while grown under normal and stress conditions [79].…”

“…PNSB has also shown the potential to enhance the contents of a variety of secondary metabolites in crops [53,79]. For example, R. palustris KL9 was reported to enhance the lycopene content in harvested tomato fruits.…”

“…For example, R. palustris KL9 was reported to enhance the lycopene content in harvested tomato fruits. R. sphaeroides KE149 was reported to increase the production of flavonoids and phenolics in soybean under normal condition [79]. Both lycopene and flavonoids have been shown to have antioxidative activities, which can provide positive effects for the maintenance of health and the prevention of diseases, such as chronic diseases, including cancer, asthma, inflammation, cardiovascular disorders, etc [177,178].…”