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The load and diversity of plant growth-promoting rhizobacteria (PGPR) are used as biomarkers to evaluate the health and quality of the soil. In the present study, the diversity of PGPRs and the physicochemical properties of the soil were used as comparative biomarkers in two adjacent soils (a pine forest soil and an agricultural soil) of the same region in Mexico City in order to investigate the effects of land use change. Bacterial diversity and physicochemical properties differed between the two soils. In the pine forest soil, PGPR were distributed at similar proportions in the Proteobactcna (29.41%), Actinobacteria (29.41%) and Firmicutes (35.29%) phyla, whereas the remaining PGPR were in Bacteroidetes (5.88%). In the agricultural soil, most PGPR belonged to the Phylum Firmicutes (50%), with the remaining belonging to Proteobacteria (22.73%), Actinobacteria (18.18%) and Bacteroidetes (9.09%). Percentages of bacteria producing indole acetic acid (90.91%) and siderophores (40.91%) were higher in agricultural soil. A canonical correspondence analysis (CCA) was used to correlate PGPR with the physicochemical characteristics of the soils. The CCA revealed that differences between both soils and the physicochemical properties of the soils affected isolated bacterial species and their distribution. These results demonstrate that the PGPR are correlated with the physicochemical properties of the soil, exhibiting differences between an agricultural soil and a pine forest soil. Additional keywords: canonical coordinate analysis, physicochemical properties., Introduction Soil micro-organisms are involved in important processes for the functioning of ecosystems, and it is estimated that in the soil 80-90% of these processes are mediated by micro-organisms (Nannipieri [...]

Zymoseptoria tritici is the most economically significant fungal pathogen of wheat in Europe. However, despite the importance of this pathogen, the molecular interactions between pathogen and host during infection are not well understood. Herein, we describe the use of two libraries of cloned Z. tritici effectors that were screened to identify effector candidates with putative pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI)-suppressing activity. The effectors from each library were transiently expressed in Nicotiana benthamiana, and expressing leaves were treated with bacterial or fungal PAMPs to assess the effectors' ability to suppress reactive oxygen species (ROS) production. From these screens, numerous effectors were identified with PTI-suppressing activity. In addition, some effectors were able to suppress cell death responses induced by other Z. tritici secreted proteins. We used structural prediction tools to predict the putative structures of all of the Z. tritici effectors and used these predictions to examine whether there was enrichment of specific structural signatures among the PTI-suppressing effectors. From among the libraries, multiple members of the killer protein-like 4 (KP4) and killer protein-like 6 (KP6) effector families were identified as PTI suppressors. This observation is intriguing, as these protein families were previously associated with antimicrobial activity rather than virulence or host manipulation. This data provides mechanistic insight into immune suppression by Z. tritici during infection and suggests that, similar to biotrophic pathogens, this fungus relies on a battery of secreted effectors to suppress host immunity during early phases of colonization., (© 2024 The Author(s). Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.)