Characterization of Plant Growth-Promoting Rhizobacteria (PGPR) From Saline Soil in Taiwan

Abstract

The agricultural sector is continuously facing myriad of problems such as yield loss due to abiotic stress as well as phytopathogen infestation. There is well established evidence that the use of plant growth-promoting rhizobacteria (PGPR) would overcome those problems and in turn improve plant growth and crop yield. In this research bacteria strains were isolated from root surface and inner tissue of plants grown in highly saline soils. The characterization includes the ability to produce aminocyclopropane-1-carboxylate (ACC), siderophore, chitinase as well as their antifungal ability. Those abilities are considered the most reliable traits for promoting plant growth. A total of 32 strains were isolated and examined, with 16 surface isolates and 16 endophytes. Thirty bacteria isolates showed capability to produce ACC deaminase with a range of values around 1.8 – 29.6 µmol/mg/h. Thirty isolates were found to secrete siderophore that resulted in halo zones around 1.5 mm - 15 mm after 7 days. Moreover, the chitinase assay showed 13 isolates having the ability to degrade chitin. Interestingly, two isolates with the highest chitinase activity also showed superior ability to inhibit fungal growth. To conclude, a procedure has been demonstrated that rhizobacteria with PGPR traits can be isolated from saline soil. Furthermore, some of these PGPR candidates showed potential to not only promote plant growth but also to control fungal pathogen. This type of dual-functional stains could serve as an environmentally friendly biofertilizer and meanwhile also a biocontrol agent in sustainable agriculture.