Isolation and Characterization of Plant Growth-Promoting Bacteria from the Rhizosphere of Medicinal and Aromatic Plant Minthostachys verticillata.

This study aimed to isolate and characterize Pseudomonas native strains from the rhizospheric soil of Minthostachys verticillata plants to evaluate their potential as plant growth-promoting rhizobacteria (PGPR). A total of 22 bacterial isolates were obtained and subjected to various biochemical tests, as well as assessments of plant growth-promoting traits such as phosphate solubilization, hydrogen cyanide production, biocontrol properties through antibiosis, and indole acetic production. Genotypic analysis via 16S rRNA gene sequencing and phylogenetic tree construction identified the strains, with one particular strain named SM 33 showing significant growth-promoting effects on M. verticillata seedlings. This strain, SM 33, showed high similarity to Stutzerimonas stutzeri based on 16S rRNA gene sequencing and notably increased both shoot fresh weight and root dry weight of the plants. These findings underscore the potential application of native Pseudomonas strains in enhancing plant growth and health, offering promising avenues for sustainable agricultural practices.

A practical method to investigate the effect of volatile organic compounds emitted by rhizobacteria on plant growth under conditions of salt stress.

Salinity is one of the causes that limit crop production. Plant Growth Promoting Rhizobacteria (PGPR) are beneficial soil bacteria that play a significant role in promoting plant growth. These microorganisms can produce their effect through the emission of Volatile Organic Compounds (VOCs). Most of the research to study the effects of microbial VOCs on plant growth has been carried out under controlled conditions using partitioned Petri dishes. In this article, we describe an alternative method that has the advantage of allowing long-term trials, being able to let the plant have a greater development in growth and height, without space limitation. In the proposed method, M. piperita were planted in glass jars containing Murashige and Skoog solid media, with a small glass vial containing Hoagland media inserted into the jar. This small vial was inoculated with the specified bacterium and served as the source of bacterial volatiles. This way plants were exposed to mVOCs without having any physical contact with the rhizobacteria.•The procedure allows studying the effect of microbial VOCs on plant growth.•It also allows longer trials, being able to let the plant develop more without space limitation.