Cand2 inhibits CRL-mediated ubiquitination and suppresses autophagy to facilitate pathogenicity of phytopathogenic fungi

Yunran Zhang; Yunyun Wei; Minghua Wu; Mengyu Liu; Shuang Liang; Xueming Zhu; Xiaohong Liu; Fucheng Lin

doi:10.1016/j.xplc.2023.100720

Cand2 inhibits CRL-mediated ubiquitination and suppresses autophagy to facilitate pathogenicity of phytopathogenic fungi

Plant Commun. 2024 Feb 12;5(2):100720. doi: 10.1016/j.xplc.2023.100720. Epub 2023 Sep 16.

Authors

Yunran Zhang¹, Yunyun Wei², Minghua Wu³, Mengyu Liu³, Shuang Liang⁴, Xueming Zhu⁴, Xiaohong Liu³, Fucheng Lin⁵

Affiliations

¹ State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; Hainan Institute, Zhejiang University, Sanya 572025, China.
² College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou 310015, China.
³ State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
⁴ State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
⁵ State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China. Electronic address: fuchenglin@zju.edu.cn.

Abstract

The ubiquitin-proteasome system and the autophagy system are the two primary mechanisms used by eukaryotes to maintain protein homeostasis, and both are closely related to the pathogenicity of the rice blast fungus. In this research, we identified MoCand2 as an inhibitor of ubiquitination in Magnaporthe oryzae. Through this role, MoCand2 participates in the regulation of autophagy and pathogenicity. Specifically, we found that deletion of MoCand2 increased the ubiquitination level in M. oryzae, whereas overexpression of MoCand2 inhibited the accumulation of ubiquitinated proteins. Interaction analyses showed that MoCand2 is a subunit of Cullin-RING ligases (CRLs). It suppresses ubiquitination by blocking the assembly of CRLs and downregulating the expression of key CRL subunits. Further research indicated that MoCand2 regulates autophagy through ubiquitination. MoCand2 knockout led to over-ubiquitination and over-degradation of MoTor, and we confirmed that MoTor content was negatively correlated with autophagy level. In addition, MoCand2 knockout accelerated the K63 ubiquitination of MoAtg6 and strengthened the assembly and activity of the phosphatidylinositol-3-kinase class 3 complex, thus enhancing autophagy. Abnormal ubiquitination and autophagy in ΔMocand2 resulted in defects in growth, conidiation, stress resistance, and pathogenicity. Finally, sequence alignment and functional analyses in other phytopathogenic fungi confirmed the high conservation of fungal Cand2s. Our research thus reveals a novel mechanism by which ubiquitination regulates autophagy and pathogenicity in phytopathogenic fungi.

Keywords: Magnaporthe oryzae; autophagy; pathogenicity; phytopathogenic fungi; regulation mechanism; ubiquitination.

MeSH terms

Autophagy* / genetics
Fungi
Ubiquitin*
Ubiquitination
Virulence

Substances

Ubiquitin