The Cultured Microbiome of Pollinated Maize Silks Shifts After Infection with and Varies by Distance from the Site of Pathogen Inoculation

Styles transmit pollen-derived sperm nuclei from pollen to ovules, but also transmit environmental pathogens. The microbiomes of styles are likely important for reproduction/disease, yet few studies exist. Whether style microbiome compositions are spatially responsive to pathogens is unknown. The maize pathogen enters developing grain through the style (silk). We hypothesized that treatment shifts the cultured transmitting silk microbiome (TSM) compared to healthy silks in a distance-dependent manner. Another objective of the study was to culture microbes for future application. Bacteria were cultured from husk-covered silks of 14 -treated diverse maize genotypes, proximal (tip) and distal (base) to the inoculation site. Long-read 16S sequences from 398 isolates spanned 35 genera, 71 species, and 238 OTUs. More bacteria were cultured from -inoculated tips (271 isolates) versus base (127 isolates); healthy silks were balanced. caused a collapse in diversity of ~20-25% across multiple taxonomic levels. Some species were cultured exclusively or, more often, from -treated silks (e.g., , , , , ). Overall, the results suggest that alters the TSM in a distance-dependent manner. Many isolates matched taxa that were previously identified using V4-MiSeq (core and -induced), but long-read sequencing clarified the taxonomy and uncovered greater diversity than was initially predicted (e.g., within ). These isolates represent the first comprehensive cultured collection from pathogen-treated maize silks to facilitate biocontrol efforts and microbial marker-assisted breeding.