Unearthing the Plant Growth-Promoting Traits of Bacillus megaterium RmBm31, an Endophytic Bacterium Isolated From Root Nodules of Retama monosperma

Abstract

Plants live in association with complex populations of microorganisms, including Plant Growth-Promoting Rhizobacteria (PGPR) that confer to plants an improved growth and enhanced stress tolerance. This large and diverse group includes endophytic bacteria that are able to colonize the internal tissues of plants. In the present study, we have isolated a nonrhizobial species from surface sterilized root nodules of Retama monosperma, a perennial leguminous species growing in poor and high salinity soils. Sequencing of its genome reveals this endophytic bacterium is a Bacillus megaterium strain (RmBm31) that possesses a wide range of genomic features linked to plant growth promotion. Furthermore, we show that RmBm31 is able to increase the biomass and positively modify the root architecture of seedlings of the model plant species Arabidopsis thaliana both in physical contact with its roots and via the production of volatile organic compounds. Lastly, we investigated the molecular mechanisms implicated in RmBm31 plant beneficial effects by carrying out a transcriptional analysis on a comprehensive set of phytohormone-responsive marker genes. Altogether, our results demonstrate that RmBm31 displays plant growth-promoting traits of potential interest for agricultural applications.

Identification of Root-Associated Bacteria That Influence Plant Physiology, Increase Seed Germination, or Promote Growth of the Christmas Tree Species Abies nordmanniana

“…However, the role of IAA on seed germination has been debated as this hormone also controls seed dormancy in other plants ( Liu et al, 2013 ). Concerning the effect of strain s50 on root morphology, the current results are in line with previous studies on production of IAA by Bacillus and Paenibacillus , and the important role of this phytohormone in shaping plant root architecture ( Pindi et al, 2014 ; Grady et al, 2016 ; Dahmani et al, 2020 ).…”

“…An involvement of IAA production by Paenibacillus sp. s37 was indicated by the increase of long lateral roots and the role of IAA in shaping plant root architecture as discussed above ( Pindi et al, 2014 ; Grady et al, 2016 ; Dahmani et al, 2020 ). Moreover, IAA producing Bacillus and Paenibacillus strains have been reported to stimulate shoot growth of Picea alba ( Wagner et al, 2019 ).…”

Bacillus circulans GN03 Alters the Microbiota, Promotes Cotton Seedling Growth and Disease Resistance, and Increases the Expression of Phytohormone Synthesis and Disease Resistance-Related Genes

“…The effect of PGPB is primarily explained by their ability to secrete metabolites (Mahmood and Kataoka, 2020) that are able to: (a) stimulate plant growth by inducing the production and release of plant growth regulators or phytohormones such as indole acetic acid (IAA) and gibberellic acid (GA); (b) enhance asymbiotic N 2 -fixation; (c) solubilize inorganic phosphate and mineralize organic phosphate and/or other nutrients; and (d) resist, tolerate, or compete with detrimental microorganisms (Lugtenberg and Kamilova, 2009;Ramakrishna et al, 2019). PGPB also indirectly promote plant growth by improving the diversity of the rhizosphere microbiome and entering inside the roots to trigger induced systemic resistance (ISR), thereby further antagonizing soil borne pathogens (Araujo et al, 2019;Dahmani et al, 2020).…”

Complete genome sequence of plant growth‐promoting and heavy metal‐tolerant Enterobacter tabaci 4M9 (CCB‐MBL 5004)

“…Plant–microbe interaction targeting heavy metal stress is an emerging technology that is underutilized, which if exploited, may provide another exciting dimension to the existing phytoremediation and rhizoremediation techniques [5]. Plant growth‐promoting rhizobacteria (PGPR) live in close association with plants where they confer to the plants an improved growth and enhanced tolerance to different environmental stress factors such as heavy metal stress [7].…”