Fig. 7.

Proposed model for the suppression of bacterial colonization of rice roots by acidification with NH₄⁺

Following the application of NH₄⁺, rice plants induce a H⁺ efflux to maintain the pH inside their cells. The consequent acidification of the rhizosphere suppresses the secretion of chemotactic substrates, including malic acid, by the roots. As a result, the growth of bacteria, such as B510, is markedly suppressed. Moreover, acidification induces the production of ROS, including H₂O₂, by the plant roots. This suppresses colonization by endophytic bacteria, such as B510.