Genetic diversity of rhizobia and plant growth promoting rhizobacteria of soil under the influence of Piliostigma reticulatum (DC.) Hochst and their impact on shrub growth

Abstract

Piliostigma reticulatum shrub is a native legume found in fallow areas in dry and semi-dry savanna soil and is used in intercropping systems. The aim was to understand the functioning of the rhizosphere, particularly the involvement of symbiotic and free living-N fixing bacteria. Soil extracts collected from P. reticulatum roots were sampled in two contrasting areas and endophytic bacterial communities were isolated using three trap host species (F. albida, A. bivenosa and V. seyal). Potential endophytic bacteria (PEB) were characterized by RFLP, nifH PCR and by 16S rRNA gene sequencing. The subsequent behavior of P. reticulatum was monitored in vitro by measuring leaf weight, biomass and chlorophyll content, after inoculation with PEB. This approach enabled isolation of 59 bacteria belonging to different genotypes. The most abundant genera were Cohnella (27.65%) among which 11 isolates clustered together and could represent a new species closely related to C. plantaginis. The other dominant genera were Paenibacillus (21.27%), Bradyrhizobium (14.89%) and Ensifer (8.5%). The nitrogen fixing gene (nifH) was detected in 21 strains and in particular, detected in a single isolate (PZS_S04) close to Cohnella xylanilytica. The strains PZS_S05 (Ensifer) and PZG_A18 (Cohnella) significantly increased certain parameters including shoot dry weight, shrub height at 90 days and photosynthetic activity (SPAD), compared to non-inoculated controls.The result obtained showed that soil under the influence of P. reticulatum roots harbored a specific diversity of endophytic bacteria including two free living-N fixing bacteria with the potential to improve the growth of P. reticulatum in natural conditions.

Bacterial endophytes inhabiting desert plants provide protection against seed rot caused by Fusarium verticillioides and promote growth in maize

“…61 However, there are limited studies on the biological potential of bacterial endophytes associated with this plant. 62 Surprisingly, the capacity of the bacterial agents to stimulate maize seed germination was not directly correlated with their ability to produce plant growth-promoting traits. In fact, some strains with high plant growth-promoting traits in vitro showed relatively weaker effects on seed germination and plant growth, while others exhibited the opposite pattern.…”

“…Indeed, Acacia albida , a typical plant of desertic areas in Africa, possesses the ability to improve crop yields 61 . However, there are limited studies on the biological potential of bacterial endophytes associated with this plant 62 . Surprisingly, the capacity of the bacterial agents to stimulate maize seed germination was not directly correlated with their ability to produce plant growth‐promoting traits.…”

Comparative genomic analysis of Cohnella hashimotonis sp. nov. isolated from the International Space Station

“…Species from this genus are used in industrial applications including fermentation, biofuel production, and wastewater treatment bioreactors (Lin et al, 2020 ; Hero et al, 2021 ; Chen et al, 2022 ; Mohammadi et al, 2022 ). As with the genus Paenibacillus , many members of the genus Cohnella are strongly associated with the plant rhizosphere environment, particularly that of legume species (Niang et al, 2018 ). Multiple novel Cohnella species have been discovered in the root nodules of leguminous plants, although only two species are known to fix nitrogen (Garcia-Fraile et al, 2008 ; Wang et al, 2012 , 2015 ; Flores-Felix et al, 2014 ; Takada et al, 2019 ).…”