摘要详情
3 / 2023-08-25 17:37:24
The Effects of Copper and Salt-Induced Stress on the Rhizosphere of Avicenna marina and Rhizobacteria Community Structure: A gene high-throughput sequencing and metabolomics analysis
Rhizobacteria,environmental pollution,Heavy metal pollution,soil degradation; food security; rhizosphere; nutrient availability; salinity,Salinity Tolerance,gene high-throughput sequencing,metabolome characterization,soil enzyme,Mangrove
摘要录用
Introduction: The presence of rhizobacteria in soils protects plants against pathogens, promotes growth, decreases pollutant uptake, and increases soil fertility. However, the role of rhizobacteria in the mitigation of stress in the mangrove ecosystem remains elusive. Thus, this study investigates the effects of salinity and copper-induced stress on rhizobacterial community structure and growth of Avicennia marina in a 4-year semi-natural experimental setup.
Method: Pot experiments were set up to investigate the growth of A. marina and changes in the rhizosphere bacterial community structure under salt and copper stress. The treatments included a salt stress group (S5Cu0, S15Cu0, and S25Cu0) and a copper stress group (S15Cu200, S15Cu400, and S25Cu400); where S5, S15, and S25 represent 5, 15, and 25‰ salt levels and Cu0, Cu200, and C400 represent 0, 200, and 400 mg L⁻¹ Cu, respectively.
Results and discussion: The results showed that dual stress in S25Cu400 significantly reduced the concentration of available Cu by 60.08% compared to S15Cu400, indicating that high salt concentration mitigated Cu bioavailability and possible toxicity to rhizobacteria and A. marina. It was observed that salt stress decreased the concentrations of L-glutamic acid and L-proline while copper stress decreased the concentrations of L-glutamate, L-proline, and p-coumaroylbutyramine. In S15Cu200 for example, the concentrations of L-glutamate, L-proline, and p-coumaroylbutyramine were significantly decreased to 72.19%, 90.44%, and 91.80%, respectively, while creatine was increased to 1.1005-fold of S15Cu0. This suggests that under salt and Cu stress, the rhizosphere microbial community maintained cellular integrity through osmoprotectants, intracellular homeostasis using metabolites such as proline, and improved intracellular utilization of organic N and energy through arginine biosynthesis with alanine, aspartate, and glutamate metabolism. The regulation of these metabolic pathways enhanced antioxidant defenses, nutrient recycling, accumulation of osmoprotectants, stability of plasma membrane, and chelation of Cu, thereby improving the stress tolerance of the microbial community and A. marina. Furthermore, the sequencing results revealed that the rhizobacterial community was changed significantly and dominated by Proteobacteria, Chloroflexi, Actinobacteriota, and Firmicutes, with the relative abundance varying between samples. Analyzing the rhizosphere soil in S25Cu400 revealed seven culturable novel bacteria strains identified as G21 (Pontibacillus sp.), G26 (Sphingomicrobium sp.), G29 (Jiella sp.), R5 (Acuticoccus sp.), R6 (Fulvimarina sp.), R9 (Fulvimarina sp.), and R10 (Jiella sp.), with 97.59%, 97.00%, 97.92%, 96.16%, 97.59%, and 98.25% similarity to the nearest related strains, respectively. These bacteria produced 14 secondary metabolites with the ability to inhibit the mobility of Aeromonas hydrophila and Pst pathogenic bacteria. Since the response mechanisms were unbalanced between treatments, it resulted in differential growth trends for A. marina in order of S15Cu200 > S15Cu0 > S25Cu0 > S5Cu0 > S25Cu400 > S15Cu400 after 4-y.Conclusion: Rhizobacteria in the rhizosphere of A. marina regulate soil processes to mitigate salt and heavy metal-induced stress and secrete secondary metabolites capable of inhibiting the activities of pathogenic microorganisms, thereby promoting the growth of A. marina.
Method: Pot experiments were set up to investigate the growth of A. marina and changes in the rhizosphere bacterial community structure under salt and copper stress. The treatments included a salt stress group (S5Cu0, S15Cu0, and S25Cu0) and a copper stress group (S15Cu200, S15Cu400, and S25Cu400); where S5, S15, and S25 represent 5, 15, and 25‰ salt levels and Cu0, Cu200, and C400 represent 0, 200, and 400 mg L⁻¹ Cu, respectively.
Results and discussion: The results showed that dual stress in S25Cu400 significantly reduced the concentration of available Cu by 60.08% compared to S15Cu400, indicating that high salt concentration mitigated Cu bioavailability and possible toxicity to rhizobacteria and A. marina. It was observed that salt stress decreased the concentrations of L-glutamic acid and L-proline while copper stress decreased the concentrations of L-glutamate, L-proline, and p-coumaroylbutyramine. In S15Cu200 for example, the concentrations of L-glutamate, L-proline, and p-coumaroylbutyramine were significantly decreased to 72.19%, 90.44%, and 91.80%, respectively, while creatine was increased to 1.1005-fold of S15Cu0. This suggests that under salt and Cu stress, the rhizosphere microbial community maintained cellular integrity through osmoprotectants, intracellular homeostasis using metabolites such as proline, and improved intracellular utilization of organic N and energy through arginine biosynthesis with alanine, aspartate, and glutamate metabolism. The regulation of these metabolic pathways enhanced antioxidant defenses, nutrient recycling, accumulation of osmoprotectants, stability of plasma membrane, and chelation of Cu, thereby improving the stress tolerance of the microbial community and A. marina. Furthermore, the sequencing results revealed that the rhizobacterial community was changed significantly and dominated by Proteobacteria, Chloroflexi, Actinobacteriota, and Firmicutes, with the relative abundance varying between samples. Analyzing the rhizosphere soil in S25Cu400 revealed seven culturable novel bacteria strains identified as G21 (Pontibacillus sp.), G26 (Sphingomicrobium sp.), G29 (Jiella sp.), R5 (Acuticoccus sp.), R6 (Fulvimarina sp.), R9 (Fulvimarina sp.), and R10 (Jiella sp.), with 97.59%, 97.00%, 97.92%, 96.16%, 97.59%, and 98.25% similarity to the nearest related strains, respectively. These bacteria produced 14 secondary metabolites with the ability to inhibit the mobility of Aeromonas hydrophila and Pst pathogenic bacteria. Since the response mechanisms were unbalanced between treatments, it resulted in differential growth trends for A. marina in order of S15Cu200 > S15Cu0 > S25Cu0 > S5Cu0 > S25Cu400 > S15Cu400 after 4-y.Conclusion: Rhizobacteria in the rhizosphere of A. marina regulate soil processes to mitigate salt and heavy metal-induced stress and secrete secondary metabolites capable of inhibiting the activities of pathogenic microorganisms, thereby promoting the growth of A. marina.
重要日期
-
会议日期
11月05日
2023
至11月08日
2023
-
10月25日 2023
初稿截稿日期
-
11月04日 2023
注册截止日期
-
11月05日 2023
报告提交截止日期
主办单位
中国科学院南京土壤研究所
承办单位
土壤与农业可持续发展全国重点实验室
联系方式
- Mr. 李秀华
- xh******@issas.ac.cn
- +86********
- 涂 晨
- CT******@ISSAS.AC.CN
- 136********
- 025*********
历届会议
-
2021年10月25日 中国 南京市(Nanjing)
第二届全国土壤修复大会 -
2018年12月04日 中国 Nanjing
第一届全国土壤修复大会
