In vitro antagonistic activity, plant growth promoting traits and phylogenetic affiliation of rhizobacteria associated with wild plants grown in arid soil

Abstract

The role of plant growth-promoting rhizobacteria (PGPR) in adaptation of plants in extreme environments is not yet completely understood. For this study native bacteria were isolated from rhizospeheric arid soils and evaluated for both growth-promoting abilities and antagonistic potential against phytopathogenic fungi and nematodes. The phylogentic affiliation of these representative isolates was also characterized. Rhizobacteria associated with 11 wild plant species from the arid soil of Almadinah Almunawarah, Kingdom of Saudi Arabia (KSA) were investigated. From a total of 531 isolates, only 66 bacterial isolates were selected based on their ability to inhibit Fusarium oxysporum, and Sclerotinia sclerotiorum. The selected isolates were screened in vitro for activities related to plant nutrition and plant growth regulation as well as for antifungal and nematicidal traits. Isolated bacteria were found to exhibit capabilities in fix atmospheric nitrogen, produce ammonia, indoleacetic acid (IAA), siderophores, solubilize phosphate and zinc, and showed an antagonistic potential against some phytopathogenic fungi and one nematode species (Meloidogyne incognita) to various extent. Isolates were ranked by their potential ability to function as PGPR. The 66 isolates were genotyped using amplified rDNA restriction analysis (ARDRA) and 16S rRNA gene sequence analysis. The taxonomic composition of the representative genotypes from both rhizosphere and rhizoplane comprised Bacillus, Enterobacter and Pseudomonas. Out of the 10 genotypes, three strains designated as PHP03, CCP05, and TAP02 might be regarded as novel strains based on their low similarity percentages and high bootstrap values. The present study clearly identified specific traits in the isolated rhizobacteria, which make them good candidates as PGPR and might contribute to plant adaption to arid environments. Application of such results in agricultural fields may improve and enhance plant growth in arid soils.

Halotolerant bacteria belonging to operational group Bacillus amyloliquefaciens in biocontrol of the rice brown stripe pathogen Acidovorax oryzae

“…Biological control with natural antagonistic microorganisms that are inhabitant in the rhizosphere was an efficient and environmentally friendly approach for controlling a variety of plant diseases (Fravel 2005;Raaijmakers et al 2009;Chowdhury et al 2015;Fan et al 2017b). Historically, a number of different bacterial groups being considered as potential antagonists and have been investigated against different plant pathogens (Yang et al 2008;Chen et al 2009;El-Sayed et al 2014;Perez et al 2015;Wang et al 2015a). Particular attention has been paid on halotolerant bacteria, which inhabit hyper saline environments and have been shown to reduce salt stress on various plants (Patel et al 2015;Wang et al 2017).…”

Impact of nanoparticles on transcriptional regulation of catabolic genes of petroleum hydrocarbon‐degrading bacteria in contaminated soil microcosms

“…One specific set of primer pairs ( 23cat) was tested in this study to evaluate the expression level of catechol 2,3 dioxygenase as an indicator for biodegradation potential in polluted soils amended with NPs using RT‐qPCR. In general, it was found by DGGE analysis that polluted soils had a bacterial community pattern that is different from that detected in similar but unpolluted soils . Contamination has led to a unique pattern in microbial populations with those having biodegradation potentials for corresponding contaminant.…”

Population and function analysis of cultivable bacteria associated with spores of arbuscular mycorrhizal fungus Gigaspora margarita

“…The same method was used to assess chitin-decomposing activity of SAB replacing GL medium by chitin medium (colloidal chitin 15 g, yeast extraction 3 g, (NH 4 ) 2 SO 4 1 g, K 2 HPO 4 1.36 g, MgSO 4 ·5H 2 O 0.3 g, ddH 2 O 1000 ml, pH 7.0). At the same time, Escherichia coli , Staphylococcus aureus, and Fusarium oxysporum were used to assess antimicrobial effects of the bacterial isolates with the reported methods (El-Sayed et al 2014). …”