Plant Growth-Promoting Bacterium from Non-Agricultural Soil Improves Okra Plant Growth

Abstract

Beneficial soil microorganisms influence nutrient recycling, soil fertility, plant growth, and productivity and reduce chemical fertilizer application. This study aimed to isolate bacteria from non-agricultural soils in the Al-Ahsa region and characterize the bacteria with the best biostimulating characteristics at the physiological, biochemical, and molecular level. DPM17, a bacterial isolate, promotes plant growth through phosphate solubilization, nitrogen fixation, and ammonia production. DPM17 also produces the phytohormones, indole acetic acid (IAA; 4.516 μg mL−1) and gibberellin (1.33 µg mL−1), and ammonia (0.06 µg mL−1). Additionally, DPM17 grows in the presence of up to 10% NaCl, indicating its halophilic nature. DPM17 was identified as Bacillus baekryungensis based on comparative sequence analysis of the 16S rRNA gene, and neighbor-joining phylogenetic analyses indicated that DPM17 was 96.51% identified to Bacillus sp. DPM17 inoculation substantially improved Abelmoschus esculentus (okra) root length, lateral root count, and dry weight from 7.03 to 9.41 (p = 0.03), 3.2 to 7.2, and 6 to 13 mg (p = 0.032), respectively. The results suggest that DPM17 enhances plant growth and can be exploited to develop efficient formulations for sustainable agriculture and food security in Saudi Arabia.

Identification, Characterization, and Growth-Promoting Effects of Bacterial Endophytes Isolated from Okra (Abelmoschus esculentus L.)

“…The four selected strains were identified as Rhizobium, Ensifer, and Pseudomonas (Table 2), indicating that their growth-promoting ability is not exclusive to a particular genus. The isolated strains used in our study showed some plant growth-promoting properties, and the same PGPR properties in okra plant growth have been previously reported [44,45,74,75]. Hence, multiple pathways exist to increase the growth of okra, and endophytic bacteria have different combinatorial growth-promoting properties.…”

“…Three inoculated strains, which did not have IAA-producing activity (Table 2), also showed okra growth-promoting ability (Figure 2), indicating that there are other ways to induce okra growth. In addition to the IAA production, other mechanisms of plant growth promotion have been reported as follows: ACC deaminase production [75,81], phosphate-solubilizing abilities [44,74,82], cellulase-pectinase activity [26,83], siderophores production [44,84], nitrogen fixation [81], organic acid production, and production of plant hormones such as IAA [44,74,75], gibberellic acid (GA3) [85], and cytokinins [74,86]. In the present study, each of the four isolates exhibited ACC deaminase activity, with Okhm3, Okhm10, and Okhm11 demonstrating phosphorus solubility (Table 2), suggesting that there are multiple pathways to promote okra plant growth.…”

Whole-Genome Sequence Insight into the Plant-Growth-Promoting Bacterium Priestia filamentosa Strain AZC66 Obtained from Zygophyllum coccineum Rhizosphere

“…IAA increases ACC production via ACC synthetase [ 24 ], and AZC66 increases plant growth via IAA production. AZC66’s growth on nitrogen-free Jensen’s medium may suggest nitrogen fixation [ 25 , 26 ]. Nitrogenase, a complex enzyme, fixes nitrogen.…”

Exploring the mechanisms of endophytic bacteria for suppressing early blight disease in tomato (Solanum lycopersicum L.)

“…and Enterobacter spp. Bacillus, Pseudomonas and Enterobacter were the most common genera of endophytic bacteria isolated from different healthy plant species ( AlAli et al, 2022 ).…”