Transmitting silks of maize have a complex and dynamic microbiome

Area of Science:

• Plant biology
• Microbiome research
• Agricultural science

Background:

• Maize silks are vital for reproduction, facilitating pollen capture and fertilization.
• Fungal pathogens like Fusarium graminearum infect silks, contaminating grain with mycotoxins such as Deoxynivalenol (DON).
• Plant health and defense mechanisms are influenced by associated microbial communities.

Purpose of the Study:

• To characterize the microbiome of maize silks, termed the transmitting style microbiome (TSM).
• To investigate the impact of fungal infection on the TSM's diversity and function.
• To establish the maize silk as a model for studying plant reproductive microbiomes.

Main Methods:

• Field cultivation of diverse maize genotypes over two years.
• MiSeq 16S rRNA gene sequencing of 328 silk samples (healthy and Fusarium graminearum-infected).
• Analysis of prokaryotic taxa, amplicon sequence variants (ASVs), and predicted metabolic functions.

Main Results:

• The TSM comprises over 5000 prokaryotic taxa, including nitrogen-fixing bacteria.
• A core TSM of 7-11 ASVs, dominated by Pantoea, was identified, showing seasonal variation.
• Fusarium graminearum infection reduced TSM diversity but increased overall microbial abundance and altered ASV composition.

Conclusions:

• Maize silks harbor complex and dynamic transmitting style microbiomes (TSM).
• The TSM exhibits a selective response to fungal infection, potentially contributing to plant defense.
• The study establishes the maize silk microbiome as a valuable model for fundamental and applied research.