P-179 - Identification of the minimal type III effector set required for infection of Nicotiana benthamiana by Pseudomonas syringae pv. tabaci 6605

Monday, July 14, 2025

13:30 - 15:15

Location: Confex Hall 3

Microbial infection strategies (pathogens & non-pathogens)

Presenting Author(s)

KK

Kana Kuroe

Okayama University
Okayama, Okayama, JAPAN

Author(s)

TN

Takafumi Nishimura

Okayama University
Okayama, Okayama, Japan
Ns

Nanami sakata

Okayama University
Okayama, Okayama, Japan
YN

Yoshiteru Noutoshi

Okayama University
Okayama, Okayama, Japan
KT

Kazuhiro Toyoda

Okayama University
Okayama, Okayama, Japan
YI

Yuki Ichinose

Okayama University
Okayama, Okayama, Japan
HM

Hidenori Matsui

Okayama University
Okayama, Okayama, Japan

Pseudomonas syringae pv. tabaci 6605 (Pta 6605) is the causal agent of wildfire disease in tobacco. Pta 6605 harbours at least 22 Type III effectors (T3Es) in its genome. T3Es are virulence factors injected into plant cells via the type III secretion system (T3SS), play essential roles in the infection of host plants. However, the specific T3Es required by Pta 6605 to infect the host plant, Nicotiana benthamiana, remain unidentified. In this study, we investigated the T3Es that contribute to Pta 6605 infection to N. benthamiana. We generated Pta 6605 poly T3E-deficient mutant (Pta DxE) series and inoculated them to N. benthamiana. Flood assay, which mimics natural opening-based entry, showed that Pta DxE mutants lacking 16 to 22 T3Es reduced disease symptoms. By contrast, infiltration inoculation, which involves direct injection into leaves, showed only two strains which lacking one or two T3Es caused no symptom. These results reveal the minimum T3E repertoire required by Pta 6605 to invasion through natural openings and symptom development in N. benthamiana.