Development of Plant-Fungal Endophyte Associations to Suppress Phoma Stem Canker in Brassica

Differences in the Production of Extracellular Polymeric Substances (EPS) and Other Metabolites of Plenodomus (Leptosphaeria) Infecting Winter Oilseed Rape (Brassica napus L.)

Species of the genus Plenodomus (Leptosphaeria) are phytopathogens of the Brassicaceae family, which includes oilseed rape. The spores of these fungi spread by airborne transmission, infect plants, and cause crop losses. The secondary metabolism of P. lingam and P. biglobosus was studied and compared, with the main focus being on the ability to produce Extracellular Polymeric Substances (EPS). In spite of the 1.5-2-fold faster growth rate of P. biglobosus on Czapek-Dox and other screening media, the average yield of EPS in this fungus was only 0.29 g/L, compared to that of P. lingam (0.43 g/L). In turn, P. biglobosus showed a higher capacity to synthesise IAA, i.e., 14 µg/mL, in contrast to <1.5 µg/mL produced by P. lingam. On the other hand, the P. lingam strains showed higher β-glucanase activity (350-400 mU/mL), compared to 50-100 mU/mL in P. biglobosus. Invertase levels were similar in both species (250 mU/mL). The positive correlation between invertase activity and EPS yield contrasted with the absence of a correlation of EPS with β-glucanase. Plenodomus neither solubilised phosphate nor used proteins from milk. All strains showed the ability to synthesise siderophores on CAS agar. P. biglobosus exhibited the highest efficiency of amylolytic and cellulolytic activity.

Special Issue “Microbial Endophytes: Functional Biology and Applications”: Editorial

Plants harbour various microbial communities, including bacteria, fungi, actinomycetes, and nematodes, inside or outside their tissues [...]

Endophytic bacterial and fungal community compositions in different organs of ginseng (Panax ginseng)

Panax ginseng (Panax ginseng C. A. Mey.) is a perennial herb of the genus ginseng, which is used as medicine with dried roots and rhizomes. With the deepening of research on ginseng, the chemical components and pharmacological effects of ginseng have gradually been discovered. Endophytes are beneficial to host plants. However, the composition of endophytes in different organs from ginseng is poorly elucidated. The report of ginsenoside production by endophytic microbes isolated from Panax sp., motivated us to explore the endophytic microbial diversity related to the roots, stems, and leaves. In this study, the V5-V7 variable region of endophytic bacteria 16S rRNA gene and V1 variable region of endophytic fungi ITS gene in different organs were analyzed by high-throughput sequencing. The diversity and abundance of endophytic microbes in the three organs are different and are affected by the organs. For example, the most abundant endophytic bacterial genus in roots was Mycobacterium, while, the stems and leaves were Ochrobactrum. Similarly, the fungal endophytes, Coniothyrium and Cladosporium, were also found in high abundance in stems, in comparison to roots and leaves. The Shannon index shows that the diversity of endophytic bacteria in roots is the highest, and the richness of endophytic bacterial was root > stem (p < 0.05). Principal coordinate analysis showed that there were obvious microbial differences among the three groups, and the endophytic bacterial composition of the leaves was closer to that of the roots. This study provides an important reference for the study of endophytic microorganisms in ginseng.