Improvement of Cupriavidus taiwanensis Nodulation and Plant Growth Promoting Abilities by the Expression of an Exogenous ACC Deaminase Gene.

Several rhizobial strains possess the ability to modulate leguminous plants ethylene levels by producing the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. While the effect of ACC deaminase has been studied in several rhizobia belonging to the Alphaproteobacteria class, not much is understood about its impact in the nodulation abilities of rhizobia belonging to the Betaproteobacteria class, which are common symbionts of Mimosa species. In this work, we report the impact of ACC deaminase production by the Betaproteobacterium, Cupriavidus taiwanensis STM894, and its role in the nodulation of Mimosa pudica. C. taiwanensis STM894 was studied following its transformation with the plasmid pRKACC, containing an ACC deaminase gene. The expression of the exogenous ACC deaminase led to increased nodulation and M. pudica growth promotion by C. taiwanensis STM894. These results indicate that ACC deaminase plays an important role in modulating ethylene levels that inhibit the nodulation process induced by both rhizobia belonging to the Alpha and Betaproteobacteria class.