Antimicrobial activity of Lafoensia pacari phenolics-containing extract against common bean phytopathogens

ABSTRACT Lafoensia pacari represents an alternative to control phytopathogens and common bean (Phaseolus vulgaris L.) diseases. This study aimed to investigate the chemical composition of L. pacari phenolics-containing extract obtained from leaves and assess its in vitro and in vivo inhibitory activity against Curtobacterium flaccumfaciens pv. flaccumfaciens, Xanthomonas axonopodis pv. phaseoli, Xanthomonas fuscans subsp. fuscans, Xanthomonas sp., Colletotrichum lindemuthianum, Fusarium oxysporum and Macrophomina phaseolina. The microbial susceptibility screening and the extract’s potential to reduce the anthracnose severity and the common bacterial blight were examined. Eleven phenolic compounds were identified, eight of which were described for the first time in L. pacari leaves: gentisic, caffeic, p-coumaric, protocatechuic and vanillic acids, luteolin, naringenin and quercetin. The L. pacari extract completely inhibited bacterial growth at the concentration of 0.62-1.25 %, as well as the mycelial growth of the C. lindemuthianum (BRM 007626) isolate at the concentration of 5 % (v/v). Under greenhouse conditions, the extract led to the control of the common bacterial blight caused by X. axonopodis pv. phaseoli (BRM 25302) in the Pérola bean cultivar and to a low efficiency in the control of anthracnose caused by C. lindemuthianum (BRM 007447) in the IPA 7419 cultivar.