Cnidium officinale Makino, a perennial crop in the Umbeliperae family, is one of Korea’s representative forest medicinal plants. However, the growing area of C. officinale has been reduced by plant disease and soil sickness caused by fusarium wilt. This study isolated rhizosphere bacteria from C. officinale, and their antagonistic activity was evaluated against Fusarium solani. Particularly, four isolated strains, namely, PT1, ST7, ST8, and SP4, showed a significant antagonistic activity against F. solani. An in planta test showed that the mortality rates of shoots were significantly low in the PT1-inoculated group. The fresh and dry weights of the inoculated plants were also higher than that of the other groups. The 16S rRNA gene sequencing identified the strain PT1 as Leclercia adecarboxylata, and downstream studies confirmed the production of antagonism-related enzymes such as siderophore and N-acetyl-β-glucosaminidase. The phosphorous solubilizing ability and secretion of related enzymes were also analyzed. The results showed that PT1 strain could be utilized as promising plant growth-promoting rhizobacteria (PGPR) and biocontrol agents (BCAs).

: Cnidium officinale Makino, a perennial crop in the Umbeliperae family, is harvested in the summer for medicinal purposes. The average temperature in Korea has recently increased, and consequently, the area used to cultivate C. officinale has been reduced, and plant disease and soil sickness have increased. In this study, rhizosphere bacteria were isolated from C. officinale, and their antagonistic activity evaluated against Fusarium solani, which is a major issue during repeated cultivation. Twenty-eight strains were isolated from the root and rhizosphere soil, of which seven showed antagonistic activity against F. solani and were further investigated. An in planta test found that the dead rate of shoots was significantly lower in the group inoculated with PT1 isolated from the root tissue and that the fresh and dry weights were also higher, when compared with the other groups. PT1 was thus considered to have antagonistic activity against F. solani. The 16S rRNA analysis identified the PT1 as Leclercia adecarboxylata, and downstream studies confirmed the production of enzymes related to antagonism, such as siderophore and N-acetyl-β-glucosaminidase. The phosphorous solubilizing ability and secretion of related enzymes were also confirmed. The results indicate that PT1 could be utilized as a PGPR to help control fusarium wilt.

Jun Young Park · Seok Hui Lee · Dae Sol Kim · Hyeon Jong Kong · Gi Heum Nam · Ji Eun Park · Yang Jin Lee · Jun Won Kang. J Plant Biotechnol 2024;51:286-93. https://doi.org/10.5010/JPB.2024.51.028.286

Plant growth-promoting rhizobacteria (PGPR) are considered promising bio-inoculants for poplar production, but their effects can vary depending on bacterial strain, host genotype, and growth environment. In this study, we evaluated the responses of ten poplar clones representing three taxonomic groups to five indigenous PGPR strains under greenhouse and open-field nursery conditions. Under greenhouse conditions, Priestia aryabhattai GJRr2, Variovorax boronicumulans HNRr1, and a mixed inoculum (Mix) showed the most consistent positive effects. Plant height increased from 86.1 ± 5.6 cm in the control to 156.0 ± 9.4 cm in the GJRr2 treatment, whereas HNRr1 produced the greatest stem diameter (9.01 ± 0.26 mm) and total fresh weight (94.0 ± 6.0 g). Clone identity explained a larger independent fraction of growth variation than bacterial strain, and the strongest integrated responses were observed in I-476, Dorskamp, and Eco28. Field responses were generally weaker, but GJRr2 and Mix still increased height, DBH, and stem volume, whereas ORa was associated with negative responses in these traits. These results demonstrate that PGPR effects in poplar are strain-specific, clone-dependent, and environmentally contingent, indicating that inoculant selection should account for both host genotype and performance stability across growth conditions.

Evaluating forest functional indicators is essential for effective forest management planning. In this study, we conducted a metagenome-based comparative analysis of the rhizosphere soils from a natural Quercus mongolica stand and an artificial Larix kaempferi stand on Mt. Gariwang, Pyeongchang, Republic of Korea. Both stands originally belonged to the same natural forest and represent the current dominant tree species. Bacterial communities were affected more by climate than by tree species. A bacterial co-occurrence network analysis showed more complex interactions in the Q. mongolica than in L. kaempferi. Conversely, fungal communities were affected more by tree species than by climate. Specifically, the Q. mongolica stand had a high ratio of saprotrophic fungi, whereas the L. kaempferi stand exhibited a higher ratio of fungi associated with nutrient decomposition and harbored a high proportion of fungi that form ectomycorrhizae with long-distance exploration types. These fungal traits serve as indicators of soil ecological changes in Q. mongolica and L. kaempferi stands. Our comparative analysis of the microbial communities of Q. mongolica and L. kaempferi, representative plantation species in the Republic of Korea, revealed seasonal and host species–specific bacterial and fungal associations, and fungal communities were less variable than bacterial communities and more accurately reflected host tree traits.