Bacterial Pathogens and Plant Cell Death

Group Structure

Group Leader: Marc Valls (UB Associate Professor)
Career Track Fellow: Núria Sánchez Coll (since July 2012)
Postdoctoral Researchers: Haibin Lu (since October 2013), Andrea Paola Zuluaga Cruz (until September 2013)
PhD Students: Crina-Mihaela Popa, Freddy Monteiro (until July 2013), Marina Puigvert (since September 2013)
Undergrad or Master Students: Pol Rey (since August 2012), Marc Planas (since July 2014), Ainara Luque (July 2013), Javier Comino (March-June 2013), Sergio Gil (since November 2013)

Summary

Our main goals are the following:

  1. To decipher the virulence determinants of bacterial plant pathogens: We use as a model the soil-borne, wide-host range pathogen Ralstonia solanacearum, which causes the devastating bacterial wilt disease. In order to study the molecular mechanisms controlling R. solanacearum pathogenicity we developed a set of genetic tools that allows the determination of promoter activities both in vitro and in planta, complementation of mutants and protein overexpression. We are also characterizing novel R. solanacearum effectors, unmasking their molecular function and contribution to disease. As a first example, we have characterized the awr gene family, encoding secreted type III effectors involved in virulence and avirulence activities on solanaceous plants.
  2. To characterize the main executioners of the pathogen-triggered programmed cell death: Our previous studies established the plant metacaspase AtMC1 as a positive regulator of pathogen-triggered programmed cell death. We have now explored the linkage between plant autophagy and AtMC1 function in the context of pathogen-triggered programmed cell death and aging. We observed that in young plants autophagy acts as a positive regulator of pathogen-triggered programmed cell death in a parallel pathway to AtMC1. Moreover, we uncover a pro-survival homeostatic function of AtMC1 in aging plants that acts in parallel to a similar pro-survival function of autophagy. We believe that this functional switch is key to promote either death or survival in plants depending on their developmental stage and the environmental challenges to which they are exposed.

Research Projects

  • Environmental cues controlling Ralstonia solanacearum pathogenicity in plants
  • Transcriptome analysis of the wild potato Solanum commersonii after inoculation with Ralstonia solanacearum using RNAseq
  • Identification of the molecular targets of the Ralstonia solanacearum AWR effector family
  • Characterization of the regulatory nodes controlling pathogen-triggered programmed cell death
  • Role of the cell death proteases metacaspases in root development and their role in root immunity

Selected Publications

Monteiro F., Genin S., van Dijk I., Valls M.
A luminescent reporter evidences active expression of Ralstonia solanacearum type III secretion system genes throughout plant infection
(2012) Microbiology (United Kingdom), vol. 158 (8), pp. 2107-2116

Monteiro F., Sole M., Van Dijk I., Valls M.
A chromosomal insertion toolbox for promoter probing, mutant complementation, and pathogenicity studies in Ralstonia solanacearum
(2012) Molecular Plant-Microbe Interactions, vol. 25 (4), pp. 557-568

Sole M., Popa C., Mith O., Sohn K.H., Jones J.D.G., Deslandes L., Valls M.
The awr gene family encodes a novel class of Ralstonia solanacearum type III effectors displaying virulence and avirulence activities
(2012) Molecular Plant-Microbe Interactions, vol. 25 (7), pp. 941-953

Coll N.S., Valls M.
Current knowledge on the Ralstonia solanacearum type III secretion system
(2013) Microbial Biotechnology, vol. 6 (6), pp. 614-620

Peeters N., Guidot A., Vailleau F., Valls M.
Ralstonia solanacearum, a widespread bacterial plant pathogen in the post-genomic era
(2013) Molecular Plant Pathology, vol. 14 (7), pp. 651-662

Zuluaga A.P., Puigvert M., Valls M.
Novel plant inputs influencing Ralstonia solanacearum during infection
(2013) Frontiers in Microbiology, vol. 4 (NOV), Art. number Article 349