Salicylic acid-dependent immunity contributes to plant sheath blight resistance

October 20, 2017

Sheath blight caused by the fungal pathogen Rhizoctonia solani is a major disease of rice and biomass crops. Researchers from Okayama University and RIKEN CSRS have found that a phytohormone salicylic acid (SA)-dependent immunity contributes to plant resistance against sheath blight. They assessed effects of phytohormone-induced resistance to R. solani in rice and a model grass plant Brachypodium distachyon. They found that a pretreatment with SA induces R. solani resistance in plants and SA-deficient transgenic rice plants are more susceptible to R. solani than wild-type rice plants. Moreover, they identified sheath blight-resistant B. distachyon accessions that activate SA-dependent signaling upon R. solani inoculation.

Plant pathogens are classified into biotrophs and necrotrophs on the basis of their nutrient feeding strategies. Biotrophs infect and feed on living host cells. Necrotrophs kill host cells, often by producing phytotoxins, and feed on damaged host tissues. To date, it has been believed that SA is required for plant biotrophic resistance and other phytohormones jasmonic acid and ethylene are important to plant necrotrophic resistance. Our finding that SA contributes to plant sheath blight resistance suggests that R. solani may presumably have a biotrophic stage during its infection process, although R. solani had been considered to be a simple necrotrophic pathogen. This work may provide novel strategies for controlling sheath blight by targeting the biotrophic nature of R. solani.

Original article
New Phytologist doi:10.1111/nph.14849
Y. Kouzai, M. Kimura, M. Watanabe, K. Kusunoki, D. Osaka, T. Suzuki, H. Matsui, M. Yamamoto, Y. Ichinose, K. Toyoda, T. Matsuura, I. C. Mori, T. Hirayama, E. Minami, Y. Nishizawa, K. Inoue, Y. Onda, K. Mochida, Y. Noutoshi,
"Salicylic acid-dependent immunity contributes to resistance against Rhizoctonia solani, a necrotrophic fungal agent of sheath blight, in rice and Brachypodium distachyon".
Yusuke Kouzai; Special Postdoctoral Researcher
Keiichi Mochida; Team Leader
Cellulose Production Research Team