Interactive Effects of Plant Growth-Promoting Rhizobacteria and CO2 levels on Prince Ginseng Health and Quality

The cultivation of medicinal plants focuses not only on biomass yield, but also on the health and quality of medicinal organs with therapeutic effects. Threatened by soil-borne pathogenic fungi Fusarium, the health and quality of Prince Ginseng Pseudostellaria heterophylla (P. heterophylla) is severely reduced. Plant growth-promoting rhizobacteria (PGPR), as a promising sustainable alternative, have demonstrated potential for biocontrol and soil fertilisation. However, PGPR efficacy is significantly influenced by abiotic factors, such as atmospheric CO₂ concentration, which govern plant growth. To investigate the interactive effects of PGPR (Bacillus subtilis and Pseudomonas fluorescens) and CO₂ levels (425 ppm and 1000 ppm) on P. heterophylla tuber health and quality, greenhouse experiments were conducted. Results show that Pseudomonas fluorescens, coupled with elevated CO₂, synergistically decreases tuber disease incidence by 73% and increases the content of active ingredient polysaccharide by 253%. These improvements can be attributed to the suppressed abundance of Fusarium oxysporum and enhanced root development. Biocontrol bacteria, including Actinobacteria and Proteobacteria, are recruited, especially the genera Bradyrhizobium and Rhodanobacter. The reshaping of the rhizosphere microbiome is accompanied by the upregulation of biological pathways related to metabolite biosynthesis in the rhizosphere. Furthermore, increased indole-3-acetic acid production by PGPR under elevated CO₂ signficantly promote root growth. Together, PGPR, particularly Pseudomonas, synergistically interact with elevated CO₂ to enhance the health and quality of Prince Ginseng. This study sheds light on how PGPR interacts with abiotic factors influencing plant growth, providing a strategic framework for the sustainable cultivation of high-quality medicinal plants. 

 

The authors would like to acknowledge the financial support provided by the State Key Laboratory of Climate Resilience for Coastal Cities (ITC-SKLCRCC26EG01) and the Research Grants Council of HKSAR (C5033-23G).