AUTHOR=Wei Miaomiao , Wang Aijun , Liu Yao , Ma Li , Niu Xianyu , Zheng Aiping 

TITLE=Identification of the Novel Effector RsIA_NP8 in Rhizoctonia solani AG1 IA That Induces Cell Death and Triggers Defense Responses in Non-Host Plants

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01115

DOI=10.3389/fmicb.2020.01115

ISSN=1664-302X

ABSTRACT=<p><italic>Rhizoctonia solani</italic> AG1 IA is a necrotrophic fungus that causes rice sheath blight, one of the most significant rice diseases in the world. However, little is known about the pathogenic mechanisms and functions of effectors in <italic>R. solani</italic> AG1 IA. We performed functional studies on effectors in <italic>R. solani</italic> AG1 IA and found that, of 11 putative effectors tested, only RsIA_NP8 caused necrosis in the leaves of <italic>Nicotiana benthamiana</italic>. The predicted signal peptide of this protein was required to induce cell death, whereas predicted N-glycosylation sites were not required. RsIA_NP8 was upregulated during early infection, and the encoded protein was secreted. Furthermore, the ability of RsIA_NP8 to trigger cell death in <italic>N. benthamiana</italic> depended on suppressor of G2 allele of Skp1 (SGT1) and heat shock protein 90 (HSP90), but not on Mla12 resistance (RAR1) and somatic embryogenesis receptor-like kinase (SERK3). A natural variation that prevents the triggering of cell death in <italic>N. benthamiana</italic> was found in RsIA_NP8 in 25 <italic>R. solani</italic> AG1 IA strains. It is important to note that RsIA_NP8 induced the immune response in <italic>N. benthamiana</italic> leaves. Collectively, these results show that RsIA_NP8 is a possible effector that plays a key role in <italic>R. solani</italic> AG1 IA–host interactions.</p>