Construction of a stable expression vector for Leifsonia xyli subsp. cynodontis and its application in studying the effect of the bacterium as an endophytic bacterium in rice.

To study the possibility of utilizing genetically engineered Leifsonia xyli subsp. cynodontis (Lxc) as an endophytic bacterium in rice, we constructed an Escherichia coli-Lxc shuttle vector, pLGUS, containing a beta-glucuronidase reporter gene, which was stable both in vitro and in vivo. Lxc grows and expresses the beta-glucuronidase reporter gene in all parts of rice, except for seed. A 2-year field study using three rice varieties from China showed that Lxc inoculation did not have a negative effect on the growth and yield of any of these varieties. Therefore, Lxc has the potential to be used as a benign endophyte for the expression of foreign genes in rice.