Labeling, Curing and Identification of Nodulation Ability of Symbiotic Plasmids in Mesorhizobium huakuii

Abstract:

The symbiotic plasmid pMh7653Rb of Mesorhizobium huakuii strain 7653R was labeled by Tn5-mob-sacB insertion, the mutant strain 7653RT14 labeled its symbiotic plasmid was obtained . Plasmid curing experiment was carried out using the sacB positive selection method, the derivative 7653R-1 of symbiotic plasmid cured was obtained. Transpositional frequency of transposon Tn5-mob-sacB was higher than 10-5. Cultural characteristics of the mutant derivatives were similar to wild type strain 7653R. The nodulation tests presented that 7653RT14 could form pink effective nodules, the result showed that pMh7653Rb inserted by Tn5-mob-sacB did not lost nodulation ability. However, 7653R-1 lost nodulation ability or only formed a few small null nodules. The results of stability tests indicated that 7653RT14 carrying symbiotic plasmid inserted by Tn5-mob-sacB was stably inherited under the conditions tested, and could be used as donor strain of symbiotic plasmid transfer.