Mechanism of Pantoea ananatis in the biocontrol of rice bacterial leaf blight

The isolated strains ZJU1-ZJU18 were all identiffed as <i>P. ananatis</i>, and they exhibited plant growth-promoting traits, including phosphate solubilization, siderophore production, and indole-3-acetic acid synthesis. Furthermore, strains ZJU1-ZJU18 did not induce rice bacterial leaf blight symptoms under the experimental conditions, with the lesion inhibition rate against this disease ranging from 95.14 to 97.92%. Mechanistic investigations revealed that <i>P. ananatis</i> suppressed <i>Xoo</i> via nutrient competition, dominating co-culture systems (>90% relative abundance) and reducing <i>Xoo</i> colonization on rice leaves by 96.78-99.00%. <i>Xoo</i> infection enhanced <i>P. ananatis</i> colonization, likely by modifying the leaf microenvironment. Furthermore, the results of species composition analysis showed that <i>P. ananatis</i> could alter the structure and diversity of the microbial community in rice leaves and reduce the abundance of <i>Xanthomonas</i> species. The principal coordinate analysis indicated that <i>P. ananatis</i> had a more signiffcant impact on the microbial community composition than <i>Xoo</i>. This study found that <i>P. ananatis</i> may inhibit the pathogen <i>Xoo</i> through nutrient competition and reshape the microbial structure at the community level.