English
Identification of Host-Specific Effectors from Fusarium oxysporum f. sp. fragariae
in Strawberry
SeoWoo Beak1, Do Yoon Lim1, Suho Lee1, Marc Semunyana1, Hyun-ju Kim1, Jun Namgung1, Eun-kyu Choi1, Kyujeong Lim1, Gil-Joon Choi1, Ji-Eun Lee1, Je Hyeok Yoo2, Geonu Lee2, Inha Lee2, Jiyoung Min1, Sun Ha Kim1 and Sang-Keun Oh1*
1Department of Applied Biology, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 34134, Korea
2 Strawberry Research Institute, Chungcheongnam-do Agricultural Research and Extension Services (ARES). Nonsan, 32914, Korea
*Email: sangkeun@cnu.ac.kr
Fusarium oxysporum f. sp. fragariae (Fof) is a soil-borne vascular wilt pathogen of strawberry that infects roots and colonizes the xylem, causing systemic wilting. It produces secreted in xylem (SIX) effectors, small cysteine-rich proteins with N-terminal signal peptides that determine virulence and host specificity. Here, we generated full-length coding sequences of candidate Fof effector genes identified through in silico analysis and cloned them into the pGR106 vector for in planta expression. The presence of these genes in Fof isolates was confirmed by PCR, and they were predicted to encode small secreted proteins with N-terminal signal peptides. Agroinfiltration assays demonstrated that their expression triggered a hypersensitive response (HR) in strawberry leaves. These results provide molecular evidence for elucidating virulence or avirulence factors in strawberry. Two candidate effectors induced hypersensitive response (HR)-associated cell death when transiently expressed in strawberry leaves, suggesting host-specific recognition and effector-triggered immunity. In contrast, no HR was observed in Nicotiana benthamiana, indicating that recognition of these effectors is host-specific. These results suggest that Fof candidate effectors are specifically recognized by putative resistance components in strawberry, leading to hypersensitive response-associated cell death. The absence of HR in Nicotiana benthamiana further supports the idea that their recognition depends on host-specific immune factors. Collectively, our findings imply that these effectors may function as avirulence determinants in strawberry and could differentially interact with host immune pathways involved in effector-triggered immunity.
