Epiphytic and endophytic bacteria for the control of Botrytis cinerea in vitro and in grape berries of cv. sauvignon blanc in southern Brazil

Botrytis bunch rot (BBR) in grapevines caused by Botrytis cinerea is a pre- and post-harvest disease that leads to significant losses in southern Brazil. This study aimed to assess the potential of epiphytic and endophytic bacteria to control B. cinerea in vitro and in vivo in the cv. Sauvignon Blanc (SB). B. cinerea and epiphytic and endophytic bacterial isolates were obtained from the grape clusters and leaf phyllosphere (epiphytic and endophytic) of the SB variety, respectively. Four epiphytic and two endophytic isolates that showed the highest antibiosis indices in vitro and in vivo were identified using phenotyping and DNA sequencing. Treatments were carried out in a completely randomized experimental design with five replications, including (a) control, (b) B. cinerea, (c) commercial product (EcoshotÒ) with Bacillus amyloliquefaciens, (d) epiphytic bacteria, and (e) endophytic bacteria. Among the 52 isolates, 4 epiphytic and 2 endophytic isolates showed the highest degree of inhibition and significantly inhibited the growth of B. cinerea. The UEP40, UEP43, UEN13, and UEN14 isolates yielded positive reactions for urea and indole. The epiphytic isolates UEP43 (identified as Serratia marcescens) and UEP51 (Curtobacterium flaccumfaciens pv. flaccumfaciens) and the endophytic isolate UEN13 (Staphylococcus equorum) reduced the severity of BBR on detached grape berries by ~55% and 49% between 72 and 168 h after inoculation, respectively. These bacterial isolates are potential biocontrol agents against B. cinerea. However, more research is needed to confirm their efficacy in vineyards in southern Brazil.