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In the present study, the molecular profiles of rhizospheric bacterial communities of Tagetes terniflora, T. remotiflora and T. coronopifolia were analyzed at different times using soil samples under greenhouse conditions. To this end, samples spanning were obtained at 3, 30, 60 and 90 days. Metagenomic DNA was extracted and the 16S rDNA genes were amplified by PCR-touchdown to reduces the formation of spurious by-products. The amplified fragments were run through Denaturing Gradient Gel Electrophoresis (DGGE) to obtain their molecular profiles. Shannon's index showed a decline of bacterial diversity over time. Also, to visualize spatial proximities by species, a non-metric MDS ordination was conducted, generating a stress value of 0.179. A one way-ANOSIM showed significant differences between T. terniflora and T. coronopifolia (R = 0.78, p <0.05), and between T. remotiflora and T. coronopifolia (R = 0.791, p <0.05). Sequencing of some DGGE profiles bands showed that Pseudomonas was present at 3, 30 and 60 days in all species of Tagetes, while Chloroflexus and Delftia were present at 3 and 60 days in T. remotiflora and T. coronopifolia, respectively. The study demonstrated that the beneficial populations were positively selected and sample time and species affect the dynamic succession in the rhizobacteria communities. [ABSTRACT FROM AUTHOR]

Sporisorium reilianum is the causal agent of head smut in corn, a worldwide disease that causes significant economic losses in the principal areas where maize is cultivated. To attack this problem, resistant commercial hybrids and synthetic fungicide seed treatment have been used, but with low effectiveness. In this study, a native strain of Bacillus subtilis isolated from the soil of corn crops in Mixquiahuala, Hidalgo, in central Mexico, was applied as a seed treatment in the field to test for the biological control of head smut. It significantly decreased the Smut Incidence Percentage (SIP) while increasing maize productivity. This work represents the first report in which B. subtilis has been used to control S. reilianum in the field. [ABSTRACT FROM AUTHOR]

In this work was to evaluate the conidiospores production of Trichoderma harzianum using barley straw as substrate. Four growth conditions were used; washed and unwashed barley straw and washed and unwashed barley straw supplemented with mineral salts. The highest spore production was observed when washed barley straw supplemented with mineral salts with 1.56 × 10 10 conidiospores/gram of dry matter (gdm) at 216 h of cultivation was used. The effect of substrate moisture on spore production was studied, three initial moisture levels of the substrate were tested and it was observed that a humidity of 80 % of the substrate improves the production of conidiospores reaching a concentration of 2.35 × 10 10 conidiospores/gdm at 136 h. Finally, conidiospores viability was evaluated for 12 months by keeping them on the conidia and substrate, and viability of 71 % of the conidiospores was observed, so this maintenance method is an excellent means of conserving the conidiospores viability., Competing Interests: The authors declare that they have no conflict of interest., (© 2020 The Authors.)