Root growth improvement of mesquite seedlings and bacterial rhizosphere and soil community changes are induced by inoculation with plant growth‐promoting bacteria and promote restoration of eroded desert soil

Abstract

Soil degradation is an ecological disturbance, usually human‐caused, that negatively affects the vegetation and climate of an ecosystem, particularly arid and semiarid environments. These degraded soils can be restored by using native perennial plants inoculated with specific microorganisms. We studied the changes in root growth and the rhizosphere bacterial community of mesquite seedlings (Prosopis articulata) after inoculation with the endophytic bacteria Bacillus pumilus ES4, over 3 cycles of growth in the same soil under desert climatic conditions, and found that inoculation significantly enhanced root biomass during the growth cycles but not shoot biomass or root and shoot lengths. Fluorescent in situ hybridization analysis demonstrated that B. pumilus colonized the root cap, apical meristem, and elongation zone, forming small colonies, on roots from soil‐grown mesquite. Inoculation also significantly changed the bacterial community structure of rhizophere and nonrhizosphere (without plants) soils based on denaturing gradient gel electrophoresis profiles. The changes were highly stable, and the bacterial community structure was maintained throughout the experimental period and not affected by plant replacement. The 16S rRNA pyrosequencing confirmed the changes on structure of bacterial community and revealed an impact on the top taxonomic levels analyzed. The rhizospheres of inoculated plants showed a significant increase in the abundance of Proteobacteria and Acidobacteria coupled with a concomitant decrease in Actinobacteria, whereas an opposite response was observed in nonrhizospheric degraded soils. Overall, inoculation with B. pumilus reduced bacterial diversity but increased the Rhizobium population in the soil. The class Bacilli, despite B. pumilus inoculum, showed minimal variation.

Desert Microbes for Boosting Sustainable Agriculture in Extreme Environments

“…Interestingly, the inoculation of B. pumilus increased the abundance of Rhizobia strains in the mesquite rhizosphere, which is assumed to be due to the reactivation of rhizobia; due to a higher carbon content after the reintroduction of the PGPR and restoration of the soil fertility (Galaviz Bustamante et al, 2018).…”

Co‐inoculation ofBacillussp. andPseudomonas putidaat different development stages acts as a biostimulant to promote growth, yield and nutrient uptake of tomato

“…Bacillus pumilus ES4 can colonize young roots and gradually enhance biomass, nutrient uptake and soil health in successive growth cycles (Galaviz et al . ). Bacillus mojavensis RRC101, a maize‐endophytic bacterium, has been observed to reduce Fusarium verticillioides disease severity in maize (Blacutt et al .…”

“…are prominent soil inhabitants and are antagonistic against phytopathogens; thus playing a crucial role in plant and soil health (Chen et al 2007;Jiang et al 2015;Mahmood et al 2017). Bacillus pumilus ES4 can colonize young roots and gradually enhance biomass, nutrient uptake and soil health in successive growth cycles (Galaviz et al 2018). Bacillus mojavensis RRC101, a maize-endophytic bacterium, has been observed to reduce Fusarium verticillioides disease severity in maize (Blacutt et al 2016).…”

Change of rhizospheric bacterial community of the ancient wild tea along elevational gradients in Ailao mountain, China

“…To the best of our knowledge, the Proteobacteria play a major role in the global carbon, nitrogen and sulfur cycling 26 . The phylum Proteobacteria was the most dominant phyla in the soil bacteria obtained from various soils ranging from agricultural land and grassland to pristine forest 27 , and was the main rhizosphere bacteria of rice, Allium tuberosum and Prosopis articulate [28][29][30] . In addition, Actinobacteria was important for decomposition of organic matter to improve the quality of agricultural soil 31 , and it may prefer acidic soil as moderately acidophilic heterotrophic bacteria 32 .…”