A biotic interaction between fungi from soil within and outside the rhizosphere of potato and fungi responsible for black scurf – Rhizoctonia solani Kühn and silver scurf – Helminthosporium solani (Dur., Mont.). It was found that fungi population connected with crop environment under investigation promoted the growth of Rhizoctonia solani, thus indicating no resistance of this environment to this pathogen. These fungi, however, inhibited the growth of Helminthosporium solani.

The aims of this study were to prospect Penicillium and Talaromyces species associated with Austrocedrus chilensis in sites with and without Austrocedrus Root Disease (ARD), which is caused by the pathogen Phytophthora austrocedri; and to find Penicillium sp. strains with biocontrol activity against this disease. Isolations from sites with and without the prevalence of ARD were made, and the obtained isolates were phenotypically and molecularly identified to species level. Several Penicillium species were isolated from all sites; five of them were exclusively isolated from sites with ARD. Penicillium communities were compared through multivariate analyses; communities were more complex in sites with ARD. Biocontrol activity of Penicillium and Talaromyces isolates was evaluated using co-cultures with Ph. austrocedri. Penicillium glabrum, T. amestolkiae, P. palitans, and P. crustosum showed the highest biocontrol effect. Our results highlight that Penicillium species have high biocontrol activity, which also reinforces the hypothesis that some Penicillium species could be used in formulating a control strategy.

As revolutionary advances in science and technology make the world increasingly complex, initiatives that combine science and art become more important than ever. “Rhizosphere: The Big Network of Small Worlds” is a project that brings together art, science, and technology.

The object of the studies conducted in the years 2000–2002 on a field of 3 years’ monoculture of soybean was rhizosphere soil of soybean cultivated after tansy phacelia, winter wheat, white mustard, rye, agrimony and soybean as previous crops. The purpose of the studies was to determine the effect of cultivating the above listed previous crop plants on the formation of microorganism communities in the rhizosphere soil of soybean. The lowest total number of fungal colonies was found in the rhizosphere soil of soybean cultivated after rye and winter wheat (21.09 × 10³ and 22.58 × 10³ c. f. u., respectively), while the highest number was found in soil after soybean (36.95 × 10³ c. f. u.). The highest total number of bacteria was found in 1 g of dr yweight of the rhizosphere soil of so ybean cultivated after agrimony, and the lowest after soybean (5.80 × 10⁶ and 4.09 × 10⁶ c. f. u., respectively). The largest proportion of pathogenic fungi was characteristic of the rhizosphere soil of soybean cultivated after soybean, and the smallest – of the rhizosphere soil of soybean after agrimony as a previous crop. The dominating species among pathogenic fungi in all experimental objects was Fusarium oxysporum. The rhizosphere soil of soybean cultivated after soybean was the poorest in saprophytic fungi (35.2% of all isolations). On the other hand, the highest number of saprophytes, including antagonistic ones, was found in the rhizosphere soil of soybean after agrimony and winter wheat.

Root associated bacteria were isolated from Suaeda nudiflora and two isolates were selected for this study: rhizospheric Bacillus megaterium and endophytic Pseudomonas aeruginosa. These isolates were inoculated into maize variety Narmada Moti during its germination. TTC (2, 3, 5-triphenyl tetrazolium chloride) staining was used to confirm the association of the isolates with the maize root. The effects of these root associated bacteria were tested alone and in combinations for cell wall reinforcement and the induction of defense enzymes such as phenylalanine ammonia lyase (PAL) and β-1,3-glucanase in the presence of fungal pathogen Aspergillus niger in maize. The results indicated that the rhizospheric bacteria had a greater fight response to fungal infection than the endophhytic bacteria due to cell wall lignification as well as the rapid induction of higher concentrations of defense related enzymes.