Light modulates the switch to the pathogenic stage in Pseudomonas syringae pv. tomato DC3000
S. SANTAMARÍA HERNANDO (1), I. Del Río Álvarez (2), J. Rodríguez Hervá (2), E. López Solanilla (2) (1) Centre for plant biotechnology and genomics-Universidad Politécnica de Madrid, Spain; (2) Centre for Plant Biotechnology anf Genomics-Universidad Politécnica de Madrid, Spain

Pseudomonas syringae pv. tomato DC3000 (Pto) is the causal agent of the bacterial speck of tomato, which causes significant economic losses worldwide. This bacterium inhabits the phyllosphere, where is highly exposed to light. Light regulates plant defense mechanisms. Plant pathogens might have evolved to sense light conditions associated with different levels of plant resistance. Pto possess a blue-light sensing LOV domain and two red-light sensing bacteriophytochromes for the detection of light. We previously showed that white light controls the expression of some virulence-related genes in Pto. Furthermore, Pto swarming motility and adhesion to plant surfaces depends on light intensity and these light-controlled features during the epiphytic stage cause a reduction in virulence. Light regime changes both in intensity and quality during the day being the twilight the transition period in which the occurrence of monochromatic lights is more prevalent. We have analyzed the response of Pto to different monochromatic lights. Gene expression profile unveils the role of blue light in the control of the expression of genes related to the T3SS and of the red light in controlling coronatine expression related genes. Virulence phenotypes, both in wild type and mutants strains affected in blue and red-light photoreceptors, reveal a significant effect of monochromatic lights during the firsts stages of the interaction which determines the output of the infection.

Abstract Number: P3-80
Session Type: Poster