The plant growth-promoting rhizobacterium Streptomyces coelicolor M145 induces systemic resistance in Arabidopsis thaliana against Pst DC3000 by activating the salicylate signaling pathway
N. LIN (1), C. Chen (1) (1) Department of Agricultural Chemistry/National Taiwan University, Taiwan

Induced systemic resistance (ISR) is defined as systemic plant immunity induced by colonization of certain plant growth-promoting rhizobacteria (PGPR) or fungi (PGPF) in/on roots. We found that Arabidopsis seedlings pretreated with Streptomyces coelicolor M145 are more resistant to Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000). Here, an Arabidopsis-Pseudomonas flood-inoculation system was set up on half-strength MS medium to study the mechanisms underlying ISR triggered by S. coelicolor M145. By means of mutants defective in phytohormone signaling pathways, we demonstrated that M145-mediated ISR requires responsiveness to salicylic acid (SA). Furthermore, inoculation of S. coelicolor M145 reduced SA signaling-related defense genes such as PR1, PR2 and PR5, and also down-regulated SA biosynthesis gene, ICS1, in shoot. However, upon Pst DC3000 infection, faster and stronger expression of PR5, PDF1.2, VSP2 and GST2 could be observed in Streptomyces-treated seedlings when compared to seedlings without Streptomyces treatment. These data indicate that Streptomyces induces Arabidopsis defense responses against Pst DC3000 through modulating genes involved in SA and JA/ET signaling pathways.

Abstract Number: P16-457
Session Type: Poster