Rhizobium etli CE3-DsRed pMP604: a useful biological tool to study initial infection steps in Phaseolus vulgaris
Raúl Dávila-Delgado1, Luis Alfredo Bañuelos-Vazquez2, Elizabeth Monroy-Morales1
1Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Colonia Chamilpa, 62210, Cuernavaca, Morelos, México.
Main Conclusion:
Rhizobium etli CE3-DsRed pMP604 drives infection 12-24 h earlier than R. etli CE3-DsRed and it is an excellent tool in live-cell imaging studies of IT developement in P. vulgaris roots. The study of the cellular dynamics of nodulation has frequently been limited by the difficulty of performing live-cell imaging in nodule primordia and legume roots, which are constituted by multiple cell layers, such is the case of Phaseolus vulgaris. Seeking conditions to reduce the time it takes for rhizobia to infect P. vulgaris root, we decided to explore the nodulation properties of Rhizobium etli CE3 pMP604, a strain that constitutively produces Nod factors through a flavonoids-independent transcriptional activation which is often used to purify Nod factors. Even though the strain infects 12-24 h earlier than the parental R. etli CE3 strain, infection thread (IT) formation, nodule organogenesis processes and N2-fixation activity are similar for both strains. Additionally, we have confirmed that R. etli CE3-DsRed pMP604 is an excellent tool to trace IT development in P. vulgaris roots.
Insights
Rhizobium etli CE3-DsRed pMP604 accelerates legume root infection by 12-24 hours. This engineered bacterium is a valuable tool for live-cell imaging of infection thread development in Phaseolus vulgaris roots.
Area of Science:
- Plant-microbe interactions
- Molecular microbiology
- Legume symbiosis
Background:
- Live-cell imaging of legume nodulation is challenging due to multi-layered root tissues.
- Understanding rhizobial infection dynamics in Phaseolus vulgaris requires improved imaging tools.
Purpose of the Study:
- To investigate the nodulation properties of Rhizobium etli CE3 pMP604 for faster infection in Phaseolus vulgaris.
- To evaluate R. etli CE3-DsRed pMP604 as a tool for live-cell imaging of infection thread development.
Main Methods:
- Utilized Rhizobium etli CE3 pMP604, a strain with constitutive Nod factor production.
- Compared infection timing and nodulation processes with the parental R. etli CE3 strain.
- Employed live-cell imaging techniques to observe infection thread (IT) development.
Main Results:
- Rhizobium etli CE3-DsRed pMP604 initiated infection 12-24 hours earlier than the parental strain.
- Infection thread formation, nodule organogenesis, and nitrogen fixation activity were comparable between strains.
- R. etli CE3-DsRed pMP604 proved effective for tracing IT development in P. vulgaris roots.
Conclusions:
- Rhizobium etli CE3-DsRed pMP604 significantly speeds up the initial stages of legume root infection.
- This engineered strain serves as an excellent tool for advanced live-cell imaging studies of symbiotic interactions in Phaseolus vulgaris.
