Seed ageing increases the influence of native microorganisms on germination

Area of Science:

• Agricultural Science
• Microbiology
• Plant Science

Background:

• Seed quality is compromised by improper storage conditions (high temperature, humidity), accelerating ageing.
• The effects of seed ageing on the microbiome and subsequent germination performance are not well understood.

Purpose of the Study:

• To investigate how ageing soybean seeds affects fungal communities, metabolism, and germination sensitivity to fungi.
• To evaluate the role of endophytic bacteria in controlling pathogenic fungi in aged seeds.

Main Methods:

• Soybean seeds were aged at 45 °C and 75% RH.
• Fungal communities were analyzed using amplicon sequencing.
• Metabolite leakage and fungal growth were assessed.
• Endophytic bacteria were tested for antifungal activity in vitro and in vivo.
• Fluorescence in situ hybridization microscopy was used to visualize bacterial colonization.

Main Results:

• Ageing decreased fungal richness and altered community structure.
• Specific fungi inhibited germination of aged or non-aged seeds.
• Ageing increased metabolite leakage, promoting fungal growth.
• Bacillus toyonensis C55 and B. pumilus AM26 showed antifungal activity.
• B. toyonensis C55 improved germination of aged seeds, while B. pumilus AM26 did not.
• Oxidation during ageing increased sensitivity to fungal pathogens, modulated by bacteria.

Conclusions:

• Seed ageing significantly impacts the seed microbiome and increases susceptibility to fungal pathogens.
• Endophytic bacteria, particularly Bacillus toyonensis C55, can play a role in mitigating fungal infections in aged soybean seeds.
• Oxidative stress during ageing is a key factor in increased fungal pathogen sensitivity.