Symbiotic phenotypes of constitutive-expressed ctrA in Mesorhizobium huakuii 7653R and screening for its host interacting protein

• 1、State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070
• 2、 State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070

Abstract：By using the vector pBBR1MCS5, an extra copy of ctrA was introduced into Mesorhizobium huakuii 7653R. The phenotypes were examined for both free living cells and symbiosis. It was found that the growth rate of 7653R free-living cells remained unchanged, but nodule numbers in host plant Astragalus sinicus were decreased and nodule nitrogen fixation ability was reduced as well. Real time qPCR analyses showed that ctrA was constitutively expressed under cultivation and symbiosis conditions, its expression level was slightly increased due to the introduction of pBBR-ctrA plasmid. Meanwhile, basing a yeast two-hybrid system screening in Astragalus sinicus AD-cDNA library, four candidate clones which interacted with bait protein CtrA were obtained. Sequencing analyses indicated that one of the cDNA inserts encoded a JUN kinase activation domain binding protein.

Keywords： Mesorhizobium huakuii ctrA Constitutive expression Symbiotic phenotype Interacting protein