A Microbial Fermentation Product Induces Defense-Related Transcriptional Changes and the Accumulation of Phenolic Compounds in Glycine max.

With the progressive loss of fungicide efficacy against Phakopsora pachyrhizi, the causal agent of Asian soybean rust (ASR), alternative methods to protect soybean crops are needed. Resistance induction is a low impact alternative and/or supplement to fungicide applications that fortifies innate plant defenses against pathogens. Here, we show that a microbial fermentation product (MFP) induces plant defenses in soybean, and transcriptional induction is enhanced with the introduction of ASR. MFP-treated plants exhibited 1,011 and 1,877 differentially expressed genes (DEGs) 12 and 60 h after treatment, respectively, compared with water controls. MFP plants exposed to the pathogen 48 h after application and sampled 12 h later (for a total of 60 h) had 2,401 DEGs compared with control. The plant defense genes PR1, PR2, IPER, PAL, and CHS were induced with MFP application, and induction was enhanced with ASR. Enriched pathways associated with pathogen defense included plant-pathogen interactions, MAPK signaling pathways, phenylpropanoid biosynthesis, glutathione metabolism, flavonoid metabolism, and isoflavonoid metabolism. In field conditions, elevated antioxidant peroxidase activities and phenolic accumulation were measured with MFP treatment; however, improved ASR control or enhanced crop yield were not observed. MFP elicitation differences between field and laboratory grown plants necessitates further testing to identify best practices for effective disease management with MFP-treated soybean.

Bacillus subtilis and Bacillus licheniformis promote tomato growth.

Bacillus spp. are widely marketed and used in agricultural systems as antagonists to various phytopathogens, but it can also benefit the plant as plant growth promoters. Therefore, the longer presence of the bacterium in the rhizosphere would result in a prolonged growth-promoting benefit, but little is yet known about its persistence in the rhizosphere after seed coating. The objectives of this study were to evaluate the tomato growth promotion mediated by Bacillus licheniformis FMCH001 and Bacillus subtilis FMCH002 and the survival rate of these bacteria both in shoots and in the rhizosphere. The Bacillus strains used throughout this study were obtained from Quartzo® produced by Chr. Hansen. The application of a mixture of B. subtilis and B. licheniformis (Quartzo®) at concentrations 1 × 108, 1 × 109, and 1 × 1010 CFU mL-1, as well as the application of B. subtilis and B. licheniformis individually at concentration 1 × 108 CFU mL-1, increased fresh and dry masses of shoot and root system, volume of root system, and length of roots of tomato plants when compared to control. Both Bacillus strains produced IAA after 48 h of in vitro. Bacillus colonies obtained from plant sap were morphologically similar to colonies of B. subtilis and B. licheniformis strains and were detected in inoculated on plants and not detected in control ones. A similar pattern was obtained through DNA-based detection (qPCR). Therefore, B. subtilis and B. licheniformis were able to produce auxin, promote tomato growth, and colonize and persist in the rhizosphere.