Plant growth-promoting rhizobacteria associated to candelilla rhizosphere (Euphorbia antisyphilitica) and its effects on Arabidopsis thaliana seedlings

Abstract

In the communities of Sierra Mojada and Viesca, Coahuila, Mexico of Coahuila desert, two rhizosphere samplings of candelilla (Euphorbia antisyphilitica Zucc) were collected to isolate, characterize, and identifying plant growth-promoting rhizobacteria (PGPR); 165 rhizobacteria were tested in vitro with Arabidopsis thaliana seedlings to evaluate their potential as plant growth promoters, and obtaining 21 strains with best results in the variables of the number of secondary roots and fresh weight concerning the uninoculated control. Their salinity tolerance was evaluated at concentrations from 0.85 M, 1.7 M and 2.55 M of NaCl. Biochemical tests were accomplishing such as siderophores production, phosphates solubilization, production of Indole-3-acetic acid (IAA), and the activity of the ACC deaminase enzyme. The results obtained from 21 strains selected, high activities were obtained in organic substances like a siderophores since they developed a translucent orange halo around their growth; four rhizobacteria developed a clear halo around the bacterial growth with a thickness between 1.487 mm ± 0.667 mm and 5.267 mm ± 0.704 mm in phosphates solubilization; in the production of Indole-3-acetic acid (IAA), the bacterial strains showed the presence of this phytohormone, with values ​​from 4.444 μg mL-1 to 19.286 μg mL-1; and according to the activity of the ACC deaminase enzyme, values ​​from 0.424 to 1.306 µmol α-KB/h/mg Pr were showed. 16S rRNA sequencing was carried out and genus identified were Bacillus, Staphylococcus, Acinetobacter, Cronobacter and Siccibacter. The results obtained show the potential of the isolated rhizobacteria as growth promoters and the increase in the biomass of the Arabidopsis thaliana seedlings is evident. This is a first indication to proceed to carry out tests in different phenological stages in crops of agricultural importance.

Effects of mixed biocrusts on soil nutrients and bacterial community structure：A case study from Hilly Loess Plateau, China

“…Denoise the sequences using the deblur plugin 22 .The sequencing error bases were corrected and the retained sequence length was ensured to have more than 99.50% of the sequences meeting the requirements. Microbial data mining was performed using the feature table generated after denoising, and OTUs were annotated at 97% similarity using the SILVA database 23,24 .Microbial community structural diversity was calculated using the diversity plugin of QIIME2, alpha diversity was generated and non-parametric tests were performed using Kruskal-Wallis test, distance matrices for beta diversity were generated and plotted in R language (version 4.0.3) using the vegan package and ggplot2 package PCoA plots, and ANOSIM analysis was performed on each distance matrix using the vegan package. Species stacked histograms were generated using the taxa plugin for QIIME2 to count microbial species at different taxonomic levels and plotted using ggplot2 in the R language.…”