NGUYEN, T. B. H. | Search bioRxiv

bioRxiv2025

A population genetic study of Fusarium graminearum, the causal agent of Fusarium Head Blight, provides insights into patterns of inoculum dispersal in wheat fields at a regional scale

Fusarium graminearum is the primary pathogen responsible for Fusarium Head Blight (FHB) in cereals, causing yield losses and mycotoxin contamination. The present study investigated the genetic diversity and population structure of F. graminearum from wheat grains and maize residues, which were the primary inoculum sources of FHB. A total of 588 isolates from four different fields were genotyped using a sequence-based microsatellite genotyping method of 34 SSR markers (SSRseq) and characterized for chemotype distribution. The results revealed high genetic diversity with 453 distinct multilocus genotypes (MLGs) without significant genetic differentiation by geographic location or substrate, suggesting a single metapopulation at the regional scale. This absence of substrate genetic differentiation strongly supports the fact that residue-borne inoculum contributed to FHB infection, although we failed to demonstrate any field-specific dispersal pattern from residues to grains. The findings underscore the importance of maize residues as a critical inoculum source and highlight the need to consider both local and regional sources in FHB management.

genetics↗

bioRxiv2025

Regulation of gene expression under high hydrostatic pressure: the versatile role of the master regulator SurR in energy metabolism

In Thermococcus barophilus, a piezophilic hyperthermophilic archaeon, the expression of several gene clusters, including those of energy metabolism, is modulated by hydrostatic pressure. In Thermococcales, SurR, a redox-sensitive transcriptional regulator that responds to sulfur availability, regulates genes involved in energy metabolism. To better understand how high hydrostatic pressure (HHP) influences the expression of energy metabolism genes, several gene deletion mutants including surR partial knockout, were constructed and analyzed under various culture conditions, including different hydrostatic pressures and the presence or absence of sulfur. Phenotypic analysis of the surR mutant revealed that SurR affects both growth and gene expression, independently of sulfur availability. This regulatory behavior differs from that observed in non-piezophilic Thermococcales species such as Pyrococcus furiosus and Thermococcus kodakarensis. These findings suggest that hydrostatic pressure influences the physiological role or functional state of SurR in T. barophilus, highlighting its adaptive versatility in extreme environments. IMPORTANCEThis study provides new insights into the adaptive mechanisms of hyperthermophilic archaea to high hydrostatic pressure, a key factor in deep-sea environments. By demonstrating that SurR regulation differs in T. barophilus compared to non-piezophilic species, it suggests that pressure can modify transcriptional control mechanisms, potentially reshaping energy metabolism strategies in deep-sea archaea. Understanding these regulatory adaptations contributes to our broader knowledge of microbial life under extreme conditions and may have implications for biotechnology, particularly in designing pressure-resistant enzymes or metabolic pathways.

microbiology↗