Arthrobacter sp. UMCV2, and its compound N,N-dimethylhexadecilamine promote nodulation in Medicago truncatula by Sinorhizobium medicae

The actinobacterium Arthrobacter sp. UMCV2 promotes plant growth through the emission of N,N-dimethylhexadecilamine (DMHDA). The Medicago–Sinorhizobium nodulation has been employed to study symbiotic nitrogen fixation by rhizobia in nodulating Fabaceae. Herein, we isolated three Sinorhizobium medicae strains that were used to induce nodules in Medicago truncatula. The co-inoculation of M. truncatula with Arthrobacter sp. strain UMCV2 produced a higher number of effective nodules than inoculation with only Sinorhizobium strains. Similarly, the exposure of inoculated M. truncatula to DMHDA produced a greater number of effective nodules compared to non-exposed plants. Thus, we conclude that Arthrobacter sp. UMCV2 promotes nodulation, and propose that this effect is produced, at least partly, via DMHDA emission.