scholarly journals Identification of Chemotaxis Compounds in Root Exudates and Their Sensing Chemoreceptors in Plant-Growth-Promoting Rhizobacteria Bacillus amyloliquefaciens SQR9

2018 ◽  
Vol 31 (10) ◽  
pp. 995-1005 ◽  
Author(s):  
Haichao Feng ◽  
Nan Zhang ◽  
Wenbin Du ◽  
Huihui Zhang ◽  
Yunpeng Liu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Plant Growth ◽  
Organic Acids ◽  
Root Exudates ◽  
Bacillus Amyloliquefaciens ◽  
Plant Growth Promoting Rhizobacteria ◽  
Titration Calorimetry ◽  
Chemotaxis Proteins ◽  
Plant Growth Promoting ◽  
Growth Promoting

Chemotaxis-mediated response to root exudates, initiated by sensing-specific ligands through methyl-accepting chemotaxis proteins (MCP), is very important for root colonization and beneficial functions of plant-growth-promoting rhizobacteria (PGPR). Systematic identification of chemoattractants in complex root exudates and their sensing chemoreceptors in PGPR is helpful for enhancing their recruitment and colonization. In this study, 39 chemoattractants and 5 chemorepellents, including amino acids, organic acids, and sugars, were identified from 98 tested components of root exudates for the well-studied PGPR strain Bacillus amyloliquefaciens SQR9. Interestingly, mutant stain SQR9Δ8mcp, with all eight putative chemoreceptors completely deleted, lost the chemotactic responses to those 44 compounds. Gene complementation, chemotaxis assay, and isothermal titration calorimetry analysis revealed that McpA was mainly responsible for sensing organic acids and amino acids, while McpC was mostly for amino acids. These two chemoreceptors may play important roles in the rhizosphere chemotaxis of SQR9. In contrast, the B. amyloliquefaciens-unique chemoreceptor McpR was specifically responsible for arginine, and residues Tyr-78, Thr-131, and Asp-162 were critical for arginine binding. This study not only deepened our insights into PGPR–root interaction but also provided useful information to enhance the rhizosphere chemotaxis mobility and colonization of PGPR, which will promote their application in agricultural production.

scholarly journals Morphological and Metabolite Responses of Potatoes under Various Phosphorus Levels and Their Amelioration by Plant Growth-Promoting Rhizobacteria

2021 ◽  
Vol 22 (10) ◽  
pp. 5162
Author(s):  
Leangsrun Chea ◽  
Birgit Pfeiffer ◽  
Dominik Schneider ◽  
Rolf Daniel ◽  
Elke Pawelzik ◽  
...  
Keyword(s):  
Amino Acids ◽  
Plant Growth ◽  
Plant Growth Promoting Rhizobacteria ◽  
Shoot Biomass ◽  
Root Surface Area ◽  
Limiting Factor ◽  
P Availability ◽  
P Deficiency ◽  
Plant Growth Promoting ◽  
Growth Promoting

Low phosphorus (P) availability is a major limiting factor for potatoes. P fertilizer is applied to enhance P availability; however, it may become toxic when plants accumulate at high concentrations. Therefore, it is necessary to gain more knowledge of the morphological and biochemical processes associated with P deficiency and toxicity for potatoes, as well as to explore an alternative approach to ameliorate the P deficiency condition. A comprehensive study was conducted (I) to assess plant morphology, mineral allocation, and metabolites of potatoes in response to P deficiency and toxicity; and (II) to evaluate the potency of plant growth-promoting rhizobacteria (PGPR) in improving plant biomass, P uptake, and metabolites at low P levels. The results revealed a reduction in plant height and biomass 60–80% under P deficiency compared to P optimum. P deficiency and toxicity conditions also altered the mineral concentration and allocation in plants due to nutrient imbalance. The stress induced by both P deficiency and toxicity was evident from an accumulation of proline and total free amino acids in young leaves and roots. Furthermore, root metabolite profiling revealed that P deficiency reduced sugars by 50–80% and organic acids by 20–90%, but increased amino acids by 1.5–14.8 times. However, the effect of P toxicity on metabolic changes in roots was less pronounced. Under P deficiency, PGPR significantly improved the root and shoot biomass, total root length, and root surface area by 32–45%. This finding suggests the potency of PGPR inoculation to increase potato plant tolerance under P deficiency.

scholarly journals Agronomic Biofortification of Cayenne Pepper Cultivars with Plant Growth-Promoting Rhizobacteria and Chili Residue in a Chinese Solar Greenhouse

2021 ◽  
Vol 9 (11) ◽  
pp. 2398
Author(s):  
Ibraheem Olamide Olasupo ◽  
Qiuju Liang ◽  
Chunyi Zhang ◽  
Md Shariful Islam ◽  
Yansu Li ◽  
...  
Keyword(s):  
Plant Growth ◽  
Water Use Efficiency ◽  
Water Use ◽  
Bacillus Amyloliquefaciens ◽  
Net Photosynthesis ◽  
Plant Growth Promoting Rhizobacteria ◽  
Plant Growth Promoting ◽  
Use Efficiency ◽  
Growth Promoting ◽  
Agronomic Biofortification

Agronomic biofortification of horticultural crops using plant growth-promoting rhizobacteria (PGPR) under crop residue incorporation systems remains largely underexploited. Bacillus subtilis (B1), Bacillus laterosporus (B2), or Bacillus amyloliquefaciens (B3) was inoculated on soil containing chili residue, while chili residue without PGPR (NP) served as the control. Two hybrid long cayenne peppers, succeeding a leaf mustard crop were used in the intensive cultivation study. Net photosynthesis, leaf stomatal conductance, transpiration rate, photosynthetic water use efficiency, shoot and root biomass, and fruit yield were evaluated. Derivatives of folate, minerals, and nitrate contents in the pepper fruits were also assessed. B1 elicited higher net photosynthesis and photosynthetic water use efficiency, while B2 and B3 had higher transpiration rates than B1 and NP. B1 and B3 resulted in 27–36% increase in pepper fruit yield compared to other treatments, whereas B3 produced 24–27.5% and 21.9–27.2% higher 5-methyltetrahydrofolate and total folate contents, respectively, compared to B1 and NP. However, chili residue without PGPR inoculation improved fruit calcium, magnesium, and potassium contents than the inoculated treatments. ‘Xin Xian La 8 F1’ cultivar had higher yield and plant biomass, fruit potassium, total soluble solids, and total folate contents compared to ‘La Gao F1.’ Agronomic biofortification through the synergy of Bacillus amyloliquefaciens and chili residue produced better yield and folate contents with a trade-off in the mineral contents of the greenhouse-grown long cayenne pepper.

scholarly journals Influence of root exudates on the extracellular proteome of the plant growth-promoting bacterium Bacillus amyloliquefaciens FZB42

Microbiology ◽  
2015 ◽  
Vol 161 (1) ◽  
pp. 131-147 ◽  
Author(s):  
Kinga Kierul ◽  
Birgit Voigt ◽  
Dirk Albrecht ◽  
Xiao-Hua Chen ◽  
Lilia C. Carvalhais ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Exudates ◽  
Bacillus Amyloliquefaciens ◽  
Extracellular Proteome ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Bacterium Bacillus
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