Abstract: Some biochemical properties of rice endophytic diazotrophic bacteria N1 ( Bacillus pumilus), N2 ( Enterobacter cloacae) and N3 ( Enterococcus gallinarum) were characterized in this study. The plasmids harboring the reporter gene lacZ fused to the promoters of nifH and nifHDK, and the reporter gene gfp as well, were first transformed into rice endophytic diazotrophic bacteria respectively through triparental mating. After the conjugated bacteria were inoculated into tobacco Yunyan 85 and maize Jitian 6, the staining of β-galactosidase was carried out on the tobacco and maize roots and the observation was made under the confocal laser scanning microscope, transmission electron microscope and scanning electron microscope. The results showed that the rice endophytic diazotrophic bacteria were not only present in epidermal cells, cortex cells and intercellular spaces of tobacco and maize roots, but also found in vascular tissue cells of maize stem also, indicating that the bacteria had migrated from the roots into the stem. Data showed that the the fresh weight of maize plants inoculated with rice endophytic diazotrophic bacteria N3 was 18.52% more than that of the control.

Key words: Endophytic diazotrophic bacteria