Brazilian Journal of Microbiology Brazilian Journal of Microbiology
Braz J Microbiol 2018;49:685-94 - Vol. 49 Num.4 DOI: 10.1016/j.bjm.2018.01.007
Environmental Microbiology
Changes induced by co-inoculation in nitrogen–carbon metabolism in cowpea under salinity stress
Alexandra de Andrade Santosa, Joaquim Albenísio Gomes da Silveirab, Eliezer de Araujo Guilhermeb, Aurenivia Bonifacioc, Artenisa Cerqueira Rodriguesd, Márcia do Vale Barreto Figueiredoe,,
a Universidade Federal Rural de Pernambuco, Departamento de Agronomia, Recife, PE, Brazil
b Universidade Federal do Ceará, Departamento de Bioquímica e Biologia Molecular, Fortaleza, CE, Brazil
c Universidade Federal do Piauí, Departamento de Biologia, Teresina, PI, Brazil
d Universidade Federal do Piauí, Departamento de Engenharia Agrícola e Solos, Teresina, PI, Brazil
e Instituto Agronômico de Pernambuco, Recife, PE, Brazil
Received 19 August 2017, Accepted 24 January 2018
Abstract

To mitigate the deleterious effects of abiotic stress, the use of plant growth-promoting bacteria along with diazotrophic bacteria has been increasing. The objectives of this study were to investigate the key enzymes related to nitrogen and carbon metabolism in the biological nitrogen fixation process and to elucidate the activities of these enzymes by the synergistic interaction between Bradyrhizobium and plant growth-promoting bacteria in the absence and presence of salt stress. Cowpea plants were cultivated under axenic conditions, inoculated with Bradyrhizobium and co-inoculated with Bradyrhizobium sp. and Actinomadura sp., Bradyrhizobium sp. and Bacillus sp., Bradyrhizobium sp. and Paenibacillus graminis, and Bradyrhizobium sp. and Streptomycessp.; the plants were also maintained in the absence (control) and presence of salt stress (50mmolL−1 NaCl). Salinity reduced the amino acids, free ammonia, ureides, proteins and total nitrogen content in nodules and increased the levels of sucrose and soluble sugars. The co-inoculations responded differently to the activity of glutamine synthetase enzymes under salt stress, as well as glutamate synthase, glutamate dehydrogenase aminating, and acid invertase in the control and salt stress. Considering the development conditions of this experiment, co-inoculation with Bradyrhizobium sp. and Bacillus sp. in cowpea provided better symbiotic performance, mitigating the deleterious effects of salt stress.

Keywords
BNF, Plant growth-promoting bacteria, Glutamine synthetase, Acid invertase, Salinity
Braz J Microbiol 2018;49:685-94 - Vol. 49 Num.4 DOI: 10.1016/j.bjm.2018.01.007