Asoneofthemostimportantbiologicalcontrolagents (BCAs),howB.subtilisovercomestheobstacleofdistance toreachtherhizoplane,andestablishesbeneficialinterac-tionswiththerootsremainsnotwellunderstood[16–18].Chemotaxis,adirectedbacterialswimmingpropelledby flagellainaqueousenvironments,wasshowntoplayan indispensableroleinthecolonizationofB.subtilisonthe Arabidopsisthalianaroots[19,20].Meanwhile,swarming