Volume 29, Issue 5, 2020
DOI: 10.24205/03276716.2020.1096
Effect of Gibberellin and Mepiquat Chloride on Cell Growth and Structure of Rhizobia
Abstract
Plant growth regulators (PGRs) which have characteristics of improving crop resistance are used in agricultural production widely. However, there is rarely related research about PGRs on phenotype and molecular mechanism of free-living rhizobia. This is a key issue in evaluating the ecological role of PGRs. A comparative study is conducted on the effect of different concentration (10-1-10-6 v/v) of gibberellin (GA3) and mepiquat chloride (PIX) on the cell growth, pH, microstructure and nod gene expression of Ensifer fredii and Bradyrhizobia japonicum. The results show that the cell growth rate, pH and expression level of nodA and nodD are accelerated, reduced and up-regulated respectively, when adding GA3 10-3 v/v into the culture medium of E. fredii and B. japonicum. However, the cell growth rate, pH and expression level of nodA and nodD are decelerated, increased and down-regulated respectively, when adding 10-2 v/v PIX into the culture medium of E. fredii and B. japonicum. Meanwhile, the microstructure of E. fredii and B. japonicum is altered respectively by GA3 and PIX. It is indicated that PGRs could change a series of rhizobia cell phenotype through regulating expression of nod gene. These findings establish a foundation for understanding of PGRs in soil ecological security evaluation and rational application.
Keywords
Rhizobia, Plant growth regulators, nod gene, microstructure