Evaluation of indigenous bacterial strains for biocontrol of the frogeye leaf spot of soya bean caused by Cercospora sojina

SIMONETTI E.; CARMONA M; SCANDIANI M.; GARCIA A; LUQUE A; BALESTRASSE KB

LETTERS IN APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 vol. 55 p. 170 - 173

0266-8254

Aims: Assessment of biological control of Cercospora sojina, causal agent offrogeye leaf spot (FLS) of soya bean, using three indigenous bacterial strains,BNM297 (Pseudomonas fluorescens), BNM340 and BNM122 (Bacillus amyloliquefaciens).Methods and Results: From cultures of each bacterial strain, cell suspensionsand cell-free supernatants were obtained and assayed to determine their antifungalactivity against C. sojina. Both mycelial growth and spore germinationin vitro were more strongly inhibited by bacterial cell suspensions than by cellfreesupernatants. The Bacillus strains BNM122 and BNM340 inhibited the fungalgrowth to a similar degree (I 52?53%), while cells from P. fluorescensBNM297 caused a lesser reduction (I 32?34%) in the fungus colony diameter.The foliar application of the two Bacillus strains on soya bean seedlings,under greenhouse conditions, significantly reduced the disease severity withrespect to control soya bean seedlings and those sprayed with BNM297. Thislast bacterial strain was not effective in controlling FLS in vivo.Conclusions: Our data demonstrate that the application of antagonistic bacteriamay be a promising and environmentally friendly alternative to control theFLS of soya bean.Significance and Impact of the Study: To our knowledge, this is the first reportof biological control of C. sojina by using native Bacillus strains.