Producción CyT
Congreso
Autoría
Falduti, Ornella Agostina
;
Colla, Delfina
;
IGLESIAS, JULIÁN ANDRÉS
;
Mongiardini, Elias Javier
;
Torres Tejerizo, Gonzalo Arturo
;
Pérez Giménez, Julieta
Fecha
2025
Editorial y Lugar de Edición
SAMIGE
Resumen
Información suministrada por el agente en
SIGEVA
Bradyrhizobium diazoefficiens USDA 110 is a soil bacterium that forms nodules onsoybean roots. It detects flavonoids like genistein (G) released by the plant, which activatethe expression of the nodulation genes, nodYABC operon, via the NodD1 transcriptionalregulator. The Nod factors synthesized by these proteins are recognized by the plant,inducing nodule organogenesis. During the generation of the infection thread, prior tonodule development, it is reported that rhizobia can face different ty...
Bradyrhizobium diazoefficiens USDA 110 is a soil bacterium that forms nodules onsoybean roots. It detects flavonoids like genistein (G) released by the plant, which activatethe expression of the nodulation genes, nodYABC operon, via the NodD1 transcriptionalregulator. The Nod factors synthesized by these proteins are recognized by the plant,inducing nodule organogenesis. During the generation of the infection thread, prior tonodule development, it is reported that rhizobia can face different types of stresses, suchas nutritional stress. This leads to a stringent response (SR), which is mediated bymodified guanosine nucleotides, collectively referred to as (p)ppGpp. In B. diazoefficiensor Rhizobium etli, (p)ppGpp is synthesized by the Rsh protein. In R. etli, it has beenreported that the rsh mutant leads to a constitutive expression of the nodA gene. This isnot observed in the wild-type strain, in which nodA expression is only induced by theflavonoid naringenin. These results suggest a potential link between SR activation andnodulation genes expression in rhizobia. To determine whether this relationship occurs inB. diazoefficiens, a rsh mutant that is unable to synthesize (p)ppGpp was created. Thismutant showed compromised symbiosis with soybeans. The WT and rsh mutant wereused to perform qRT-PCR transcript measurements of the nodD1 gene, both underinduced conditions with G and under nutritional stress, where the SR is triggered. Anincrease in transcription levels was observed for both treatment groups in the WT strain,but not in the rsh mutant. Based on these results, we hypothesized that SR could have animplication in the expression of nodulation genes in B. diazoefficiens. In order to continuethe study of the nodD1-activated operon, a structural characterization of the proteinsencoded by nodYABC was performed using the AlphaFold and Pfam databases. TheNodY protein has two disordered domains for which no function has been characterized.In contrast, NodA protein showed a defined, organized structure and contains anaminoacyl-transferase domain that is required for nodulation. Despite nodY gene is thefirst gene to be transcribed from the nodYABC operon, NodA is the first proteinsynthesized by the operon that can be considered functional and essential for the synthesisof Nod factors. Therefore, to deeply understand how SR affects nodulation in soybeans,a deletional mutant in nodD1 gene, with the “Golden-Gate” technique, and a deletionalmutant in the nodA gene were constructed. In addition, an insertional mutant of the nodAgene, that affects the entire operon, was created. All constructions were checked by DNAsequencing. The mutants and the wild-type strain have been either subjected to nutritionalstress for one hour or not and then inoculated into pre-germinated soybean seeds. The objective of this nodulation experiments is to ascertain whether SR affects the rhizobium-soybean interaction process.
Ver más
Ver menos
Palabras Clave
ESTRESBRADYRHIZOBIUMSIMBIOSISSOJA