[The construction of Alcaligenes faecalis ntrC-lacZ fusion gene and its expression during association with rice...

A broad host range vector pLA2917 containing ntrC gene or ntrC-lacZ fusion were constructed, namely pLAC1 and pLAC2. The plasmids pLAC1 and pLAC2 were introduced into A. faecalis wild type strain A1501 by conjugation, subsequently to abtain A15C1 and A15C2. The expression and regulation of ntrC gene of A. faecalis associated with rice roots was investigated under the condition of the associative nitrogen fixation using X-Gal decoration method, micrograph and ntrC partially deletion mutant. The blue precipitation was strongly existed in parenchyma cells as well as in the lateral root primordial. It showed that ntrC gene could express at much higher level in these sites. In the presence of ammonia, the number of multi-copy ntrC conjugatants colonized on surface of rice roots is higher than that of wild type A1501, and the colonization of ntrC mutant is weakest among these three strains. This provided an evidence that ntrC gene might be involved in procedure of colonization of A. faecalis to rice roots.