Klebsiella endophytic bacteria control cassava bacterial blight in the eastern Amazon

ABSTRACT Cassava bacterial blight (CBB), caused by Xanthomonas phaseoli pv. manihotis, is one of the most important diseases affecting cassava production worldwide, including regions of Brazil in the eastern Amazon. The use of beneficial microorganisms, such as endophytic plant growth-promoting bacteria, has emerged as an effective tool for controlling diseases in many crops. Here, two Klebsiella endophytic isolates (26Y and 29Y) isolated from cassava were evaluated for the control of CBB through antagonistic assays and biological control of the disease in plants inoculated by irrigating the substrate and by foliar spray under greenhouse conditions. The two isolates were able to inhibit the in vitro growth of the pathogen, as well as to control the disease severity by at least 90% in plants inoculated by both inoculation methods. We report the first Klebsiella strains to control CBB in the eastern Amazon, though their risk assessment for drug-resistance in humans is still pending.