A Hidden Plant Growth Promoting Bacterium Isolated from In Vitro Cultures of Fraser Photinia (Photinia × fraseri)

摘要

Microbial contamination in the plant tissue culture systems considered as in vitro pathogens and should be eliminated to prevent culture loss. However, some of these contaminants could have beneficial influence on plant growth with supplying different additives and could have potential to use as bio-inoculants. Thus, isolation and characterization of these potential in vitro contaminants for production of biological compounds from plant cultures is becoming attractive for scientists. With this approach, the objective of this study was to isolate and identify putatively endophytic bacterium that was detected in the long- term in vitro cultured microshoots of fraser photonia (Photinia × fraseri Dress) and to screen its plant growth-promoting characteristics (PGPC). The strain was screened according to their phenotypical and biochemical properties together with PGPC abilities including phytostimulation, biofertilization and hydrolytic activities. Our results showed that this strain exhibited nitrogen-fixing ability as well as gibberellic acid (GA 3 ) and indole-3-acetic acid (IAA) producing capability. Gram negative putative endophytic bacterium showed similarity to uncultured bacteria and Rhizobiales according to 16S rRNA sequencing. When the proliferation medium was supported with cytokinin, maximum multiple shoot formation together with the highest microshoot length were obtained in fraser photinia in vitro cultures with the presence of bacteria. Thus, the isolated bacterial strain with various PGPC can be considered as a beneficial microbe for the facilitation of fraser photinia growth.