アドバンス生命理学特論
Topics in Advanced Biological Science
日時：12 月 5 日（火）15：30−17：00

場

所：理学部 E 館 1 階

Session #1

E131 号室

Prof. Scott C. Peck
“New Insights into the Basis of Innate Immunity in Plants”

Department ofBiochemistry,
University ofMissouri-Columbia,U.S.A.

Plants perceive potential pathogens by recognizing pathogen-associated molecular patterns (PAMPs)
through plasma membrane (PM) receptors. Recognition of flg22, a 22 amino acid PAMP derived from thebacterial flagellum, by the receptor-like kinase FLS2 induces defense signaling responses and contributesto innate immunity by restricting bacterial invasion. We have developed quantitative phosphoproteomic
technology to identify novel Arabidopsis proteins that are rapidly phosphorylated following PAMP
treatments, and using reverse genetics, we have defined functions for a number of these candidates ininnate immune responses.
Plant recognition of potential bacterial pathogens initiates the rapid deployment of defenses, thereby
preventing colonization. Much of what is known about plant resistance against bacteria involves productionof and response(s) to salicylic acid (SA). However, SA-independent mechanisms of resistance are known toexist but have been poorly defined. We found that the enhanced resistance of the MAP kinase phosphatase
1 (mkp1) mutant in Arabidopsis is genetically independent of SA production and signaling, providing
possible insights into SA-independent mechanisms. We previously reported that resistance in mkp1
involves the restriction of plant chemical signals used by virulent bacteria to induce of their type III secretion
system (TTSS), and we also reported that this mechanism appears to be shared with PAMP-triggered
immunity (PTI; Anderson et al., 2014). Because PTI, like the resistance in mkp1, previously has been foundto be independent of SA, we examined if – and confirmed that – PTI restriction of effector delivery was also
independent of SA. These results provide a simple explanation of a mode of SA-independent resistance thatcan be rapidly activated before SA production is initiated.
Anderson et al (2014) Decreased abundance of type III secretion system-inducing signals in Arabidopsis
mkp1 enhances resistance against Pseudomonas syringae. PNAS 111:6846-6851.

Session #2Asst. Prof. Jeffrey C. Anderson“Inter-Kingdom Communication: Regulation of Pseudomonas
syringae Virulence by Host Plant-derived Metabolite Signals”

Department ofBotany and Plant
Pathology, Oregon
State University,U.S.A.

My laboratory is working to understand how the plant pathogenic bacterium Pseudomonas syringae uses
host-derived metabolites as chemical cues to deploy its virulence-promoting type III secretion system(T3SS). Using a large-scale genetic screen we recently identified multiple P. syringae genes required forperception of host metabolites leading to T3SS gene expression, including predicted receptors, transporters
and transcriptional regulators. We are currently characterizing the role of these genes in perceiving hostsignals and regulating virulence. On the plant side, we hypothesize that extracellular release ofvirulence-promoting metabolites is regulated during a plant immune response, possibly as a means to limit
pathogen growth. Using biochemical and metabolomic approaches, we identified several T3SS-inducing
metabolites that are exuded from immune-activated plant cells at decreased levels. These results, as well as
progress towards defining a possible role of these metabolites in limiting bacterial growth, will be presented.

世話人：吉岡博文（生命農学研究科）hyoshiok@agr.nagoya-u.ac.jp
多田安臣（遺伝子実験施設）ytada@gene.nagoya-u.ac.jp