Dormancy and germination of microsclerotia of are regulated by soil bacteria and soil moisture levels but not by nutrients.

Front Microbiol

Plant Pathology and Plant Protection Division, Department of Crop Sciences, Faculty of Agriculture, Georg-August University Göttingen, Göttingen, Germany.

Published: September 2022

The soil-borne pathogen infects roots of its host plant, oilseed rape, and systemically colonizes stems where it finally forms microsclerotia at crop maturity. Once returned to the soil after harvest, microsclerotia undergo a stage of dormancy, in which they may survive for several years. Since there is neither efficient chemical control nor effective resistance in oilseed rape cultivars to control the disease, alternative control strategies may consist in regulating the germination and dormancy of microsclerotia in the soil. Therefore, a series of experiments were conducted to explore the effects of nutrients, soil moisture, and the soil microbiome on germination of dormant microsclerotia. Experiments with microsclerotia exposed to different nutrients indicated that under sterile conditions the stimulating effect of nutrients on microsclerotia germination was not enhanced as compared to water. Moreover, further assays revealed a strong inhibitory effect of unsterile soil on microsclerotia germination. Accordingly, oilseed rape plants inoculated with microsclerotia of showed severe infection with when grown in autoclaved soil, in contrast to plants grown in unsterile soil. These experiments indicate a crucial role of soil fungistasis and thus the soil microbiome on microsclerotia germination. Further bioassays demonstrated that viable soil bacteria obtained from the rhizosphere of oilseed rape plants and bulk field soil effectively inhibited microsclerotia germination, whereas dead bacteria and bacterial culture filtrates hardly suppressed germination. A putative inhibitory role of volatile organic compounds (VOCs) produced by soil bacteria was confirmed in two-compartment Petri dishes, where microsclerotia germination and colony growth were significantly inhibited. Bacterial VOCs were collected and analyzed by GC-MS. In total, 45 VOCs were identified, among which two acid and two alcohol compounds were emitted by all tested bacteria. A bioassay, conducted with corresponding pure chemicals in two-compartment Petri dishes, indicated that all acidic volatile compounds, including 3-methylbutanoic acid, 2-methylbutanoic acid, hexanoic acid, and 2-methylpropionic acid, induced strong inhibitory effects on microsclerotia. We conclude that bacterial acidic volatiles play a key role in the fungistatic effect on microsclerotia of in the soil and could thus be targeted for development of novel strategies to control this pathogen by artificially regulating dormancy of microsclerotia in soil.

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9539216PMC
http://dx.doi.org/10.3389/fmicb.2022.979218DOI Listing

Publication Analysis

Top Keywords

microsclerotia germination
20
soil
16
oilseed rape
16
microsclerotia
15
soil bacteria
12
microsclerotia soil
12
soil moisture
8
germination
8
dormancy microsclerotia
8
soil microbiome
8

Similar Publications

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!