Study of cytoplasmic flow velocity in Rhizophagus irregularis hyphae in relationship with Solanum tuberosum and inoculated with the biocontrol bacteria Bacillus velezensis or surfactin

Details

Supervisors

Declerck, Stephan

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences agronomiques, à finalité spécialisée

Abstract

enContext: This study builds on recent work on the beneficial interactions between microorganisms and plants, providing additional insights that will undoubtedly pave the way for future investigations. It addresses a key question for sustainable agriculture: how can certain PGPR, AMF and bacterial secondary metabolites help plants to better resist diseases, particularly potato blight (Phytophthora infestans)? Objectives: to answer this question, the study analyzed the effect of different treatments on the speed of cytoplasmic flow in the hyphae of a R. irregularis. Cytoplasmic flow being considered as a valuable indicator of hyphal activity and metabolism. Methods: under controlled conditions, bicompartmental Petri plates containing plant roots in one compartment and R. irregularis hyphae in the other compartment were submitted to hyphal compartment inoculation with H2O (control), surfactin or B. velezensis to evaluate treatment effects on hyphal cytoplasmic flow speed. Observations were made from inoculation time to 24 h post inoculation.in Petri plates, measured these speeds after different periods of time, ranging from 2 to 24 hours. After hyphal cytoplasmic flow evaluation, the plant roots were sampled for RNA extraction. Another part of the study consisted in comparing the clinical response of potato plants inoculated by two different concentrations of P. infestans sporangia. Assessment of disease progression was based on pictures analysis with Fiji. Results: We did not observe significant differences when analyzing or comparing cytoplasmic flow speeds of R. irregularis hyphae for the different treatments, except for surfactin at 2 h post inoculation. Even the H2O (control) treatment presented an important variability of results. RNA quantification and purity presented variable results that could be explained by some experimental bias. Concentration effect of P. infestans inoculation demonstrated a significant difference in favor of higher concentration only at 9 DPI. Conclusion: this study explored some aspects of the beneficial mutualistic relationship of S. tuberosum and R. irregularis in the presence of B. velezensis or surfactin. Combination of cytoplasmic flow speed measurements and RNA extraction allowed for a cross-disciplinary approach, integrating both functional observations and molecular data, providing a more comprehensive view of the interactions between microorganisms, plants and pathogens. By exploring these dynamics, this work highlights the key role that the nature and timing of a stimulus can play in regulating complex cellular processes. It thus paves the way for innovative strategies to protect crops, combining effectiveness, sustainability and respect for ecosystems.