Background : Plants cultivation is hindered by root rot, a major disease caused by the soil-born fungi. The ginseng-cultivated soil is one of the nutritious habitats for soil-borne microorganisms. Bacteria from ginseng-cultivated soil can increase plant growth by supplying nutrients and hormones as well as protecting against pathogenic fungal infections and induced systematic resistance. Methods and Results : The novel species DCY115T was isolated from ginseng-cultivated soil in Gochang province, Republic of Korea. The isolate was assigned to the genus Paraburkholderia due to its 16S rRNA gene sequence closely proximity to P. xenovorans LB400T (98.8%). Strain DCY115T is gram-negative, facultative aerobic, rod-shaped, non-flagellated, oxidase and catalase positive. The predominant isoprenoid quinone is ubiquinone Q-8. The genomic DNA G + C content is 61.3 mol%. Phenotypic tests and chemotaxonomic analysis place strain DCY115T in the genus Paraburkholderia. DNA-DNA hybridization values between strain DCY115T and closely related reference strains were lower than 51%. The DNA relatedness data in combination with phylogenetic and biochemical tests showed that strain DCY115T could not be assigned to any recognized species. Finally, strain DCY115T showed the plant growth promoting activities of siderophores production, phosphate solubilization, and antagonistic activity against root rot fungal pathogen Fusarium solani (KACC 44891T) and Cylindrocarpon destructans (KACC 44660T). Conclusion : The results support the novel strain DCY115T as a potential biocontrol agent against root rot fungal pathogen within the genus Paraburkholderia for which the name Paraburkholderia panacihumi is proposed. The type strain is DCY115T (= KCTC52952T = JCM32099T).

Background : Panax ginseng is an important crop based on its pharmaceutical efficacy in the Asian countries, it cultivated in Korea is usually harvested after 4 to 6 years of cultivation, whereas various abiotic stresses lead to a reduction of its quality. One of them is the Aluminum (Al) accumulation. Plant growth promoting rhizobacteria (PGPR) can play a role in plant health and growth and has been considered as a new trend for supporting the growth of many crops in heavy metal occupied areas. Accordingly, this study aimed to utilize PGPR to enhance the resistance of the ginseng plant against Al stress. Methods and Results : The screening of several PGPR isolated from ginseng cultivate soil had been carried out by in vitro and in planta studies to confirm the plant growth promoting traits. Amongst, the strain Rhizobium panacihumi DCY116T was registered as one novel bacteria species and found to have IAA, siderophores production and phosphate solubilization traits, heavy metal resistance activity, and antifungal activity by in vitro test. Furthermore, in the perennial plant ginseng, fifteen minutes dipping of 108 CFU/㎖ DCY116T was enough to prime 1.5-years-old ginseng seedlings against given Al stress. Ginseng seedlings treated with DCY116T showed higher biomass, active compounds (like ginsenoside, proline, total phenolic, sugars) than non-bacterized Al-stressed seedlings. DCY116T treatment induced Al stress related genes, ROS scavenging genes, ABA biosynthesis genes and root hair formation genes which prevent the Al stress. Conclusion : R. panacihumi DCY116T can be used to prime ginseng seedlings and induced its Al resistance. Also, it can promote the root hair formation. Based on these results, strain DCY116T can be as a potential plant growth promoting bacterium used in the future for the cultivation of ginseng or other kind of crop/ plant growth under Al stress.