A Leaf-Inhabiting Endophytic Bacterium, Rhodococcus sp. KB6, Enhances Sweet Potato Resistance to Black Rot Disease Caused by Ceratocystis fimbriata

Abstract

Rhodococcus species have become increasingly important owing to their ability to degrade a wide range of toxic chemicals and produce bioactive compounds. Here, we report isolation of the Rhodococcus sp. KB6, which is a new leaf-inhabiting endophytic bacterium that suppresses black rot disease in sweet potato leaves. We determined the 7.0 Mb draft genome sequence of KB6 and have predicted 19 biosynthetic gene clusters for secondary metabolites, including heterobactins, which are a new class of siderophores. Notably, we showed the first internal colonization of host plants with Rhodococcus sp. KB6 and discuss its potential as a biocontrol agent for sustainable agriculture.

Keywords: Bacterial endophyte; Rhodococcus sp.; biocontrol agent; black rot disease; sweet potato.