Alleviation of salt stress response in soybean plants with the endophytic bacterial isolate Curtobacterium sp. SAK1

Abstract

Background Salinity has been a major abiotic stressor that reduce the productivity. Previous studies reported that endophytic bacteria produce plant stress response hormones, antioxidants, and enzymes such as ACC deaminase. Augmentation of these metabolites and enzymes by endophytes mitigates the stress effects of salinity and improves plant growth and productivity. Methods Bacterial endophytes were isolated from Artemisia princeps Pamp, and evaluated for indole-3-acetic acid (IAA), abscisic acid (ABA), siderophore, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production and the ability to solubilize phosphate in the presence of NaCl (100-400 mM). SAK1 was applied to Glycine max cv. Pungsannamul to investigate salinity stress. Results Our results revealed that with an increase in NaCl concentration, the amount of ABA production in SAK1 increased, whereas IAA levels decreased. Bacterial ABA and JA degrade the reactive oxygen species and protect plants against stressors. Gas chromatography-mass spectrometry (GC-MS) analysis detected different gibberellins (GAs) and organic acids in SAK1. Interestingly, SAK1 inoculation significantly increased plant growth attributes under normal and salinity stress conditions, whereas a decrease in endogenous jasmonic acid and ABA content in the plants was recorded under salinity stress. IAA and GAs enhance number of root tips and hence improve nutrients uptake in plants. Polyphenolic oxidase and peroxidase were alleviated by elevated SAK1 in G. max plants under stress. ACC deaminase of SAK1 resulted deamination of ACC, up to 330 nmol α-ketobutyrate mg −1 h −1 which could be a major reason of ethylene reduction promoting plant growth. Conclusion SAK1 relieved salinity stress in plants by producing different phytohormones, antioxidants, and ACC deaminase enzyme. SAK1 could be a new addition in batch of plant stress hormone-regulating endophytic bacteria that mitigates the effects of salt stress and promotes plant growth in G. max.

Halo-tolerant plant growth promoting rhizobacteria for improving productivity and remediation of saline soils

“…Modulation of phytohormones and accumulation of nutrients against the hyperosmotic and hypo-nutritive conditions is an important role of HT-PGPR to confer symbiotic association and promote growth and productivity of plants. Studies confirmed that under salt stress, expression of genes for auxin like compounds increase in HT-PGPR and compensate plant’s requirement of growth hormone [102] , [89] . Apart from the improvement in growth, there is also evidence that phytohormones produced by HT-PGPR showed role in the exclusion of ionic salts.…”

“…HT-PGPR employ a vast array of mechanisms including production of low molecular weight organic acids, chelating agents and ion exchange for solubilization of P, Zn and potassium (K) in saline soil [87] , [88] . Minimizing the rhizospheric competition in nutrient scant stressed soils, some microbes through penetration or nodulation establish themselves as endophytes and in turn benefit the plant by assimilating nutrients and increasing survival/ adaption rate [89] . P is an important macronutrient required in large quantities by the plant i.e.…”

Epiphytic and Endophytic Bacteria on Olive Tree Phyllosphere: Exploring Tissue and Cultivar Effect

“…Cobrançosa cultivar had also several associated isolates described as potential antagonists of phytopathogens, such as Bacillus megaterium [80], Bacillus subtilis [81], Pantoea vagans [82] and Pseudomonas graminis [83]. Other isolates associated to Cobrançosa cultivar have been described to protect plants on stressful environments (Curtobacterium oceanosedimentum [84]). In contrast, microorganisms described as plant pathogens were detected on cv.…”

Elucidating Mechanisms of Endophytes Used in Plant Protection and Other Bioactivities With Multifunctional Prospects

“…Endophytes improve plant growth by secreting phytohormones and consequently help in nutrition improvement using bidirectional nutrient transfer and enhancement of the health of plants by protecting them against phytopathogens (Andreozzi et al, 2019;Shen et al, 2019). Plant-endophyte interaction triggers the protection of plants against harmful conditions of the environment such as heavy metal presence and drought (Khan et al, 2019;Kushwaha et al, 2019). Endophytes are numerous and studies have it that they are present in many plants; they became important due to their capacity to produce many bioactive metabolites and biotechnologically relevant enzymes (Khan et al, 2014;Rajamanikyam et al, 2017).…”