Biocontrol of Sclerotinia sclerotiorum (Lib.) de Bary on common bean by native lipopeptide-producer Bacillus strains

DANIELA C. SABATÉA; ROSA ERRA-BALSELLS; CAROLINA PÉREZ BRANDANB; M.CARINA AUDISIO; CAROLINA PÉREZ BRANDANB; M.CARINA AUDISIO; GABRIELA PETROSELLIC; GABRIELA PETROSELLIC; DANIELA C. SABATÉA; ROSA ERRA-BALSELLS

MICROBIOLOGICAL RESEARCH

ELSEVIER GMBH

Año: 2018 vol. 211 p. 21 - 30

0944-5013

Bacillus sp. B19, Bacillus sp. P12 and B. amyloliquefaciens B14 were isolated from soils of Salta province, andPGPR properties on the common bean (Phaseolus vulgaris L.) cv. Alubia and antagonistic activity againstSclerotinia sclerotiorum were studied.It was determined that B19 and P12 increased crop germination potential (GP) from the common bean by14.5% compared to control seeds; these strains also increased root length (10.4 and 15%, respectively) and stemlength (20.2 and 30%, respectively) compared to the control; however, as for the B14 strain, no increases ingrowth parameters were detected. In addition, all the treatments that combined two bacilli: B14+B19,B14+P12 and B19+P12, generated beneficial effects on GP and seedling growth compared to control seeds,but not compared to a single inoculant. B19 and P12 strains synthesized auxins at concentrations of 5.71 and4.90 mg/mL, respectively, and it was qualitatively determined that they synthesize siderophores. In addition,previous studies have determined that B14 produces auxins in a concentration of 10.10 mg/mL, and qualitativelysynthesizes siderophores.The phytosanitary state of the white bean cv. Alubia control seeds revealed bacterial contamination in 87% ofall the evaluated seeds and different fungi such as Cladosporium sp., Fusarium sp., and Rhizopus sp. Bean seedstreated with B14, B19 or P12 showed no growth of contaminating bacteria or of pathogenic fungi; in fact, bacilliinoculum development was observed in all seeds. Additionally, B19, P12 and B14 strains inhibited in vitro thedevelopment of 9 native S. sclerotiorum strains isolated from the Salta region, with FI ranging between 60 and100%. The three Bacillus strains synthesized different isoforms of the lipopeptides: surfactin, iturin, and fengycinin the presence of S. sclerotiorum, as determined by MALDI-TOF.In the in vivo trials, when common bean seeds were grown in soils contaminated with S. sclerotiorum, anincidence of 100% was determined when the seeds were not treated with any Bacillus. Seeds treated with thechemical fungicide and sown in S. sclerotiorum-infested soil did not produce seed emergence, while the inoculationof the seeds with B14+P12, B14+B19 or B19+P12 reduced the effect of the pathogen by 46, 43and 25%, respectively. Disease progression in B14+P12 and B14+B19 treatments was significantly lowerthan in the remaining treatments, with an AUDPC of 873.75 and 1071, respectively.