J Integr Plant Biol. ›› 2022, Vol. 64 ›› Issue (5): 1007-1019.DOI: 10.1111/jipb.13245

• Metabolism and Biochemistry • Previous Articles     Next Articles

WRKY33-mediated indolic glucosinolate metabolic pathway confers resistance against Alternaria brassicicola in Arabidopsis and Brassica crops

Han Tao1,2, Huiying Miao1, Lili Chen1, Mengyu Wang1, Chuchu Xia1, Wei Zeng1, Bo Sun3, Fen Zhang3, Shuqun Zhang4, Chuanyou Li5* and Qiaomei Wang1*   

  1. 1 Department of Horticulture, Zhejiang University, Hangzhou 310058, Zhejiang, China
    2 State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro‐products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture and Zhejiang Province, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
    3 College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China
    4 Division of Biochemistry, Interdisciplinary Plant Group, University of Missouri, Columbia 65211, Missouri, USA
    5 State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, the Chinese Academy of Sciences, Beijing 100101, China

    *Correspondences: Qiaomei Wang (qmwang@zju.edu.cn, Dr. Wang is responsible for the distribution of the materials associated with this article); Chuanyou Li (cyli@genetics.ac.cn)
  • Received:2021-10-14 Accepted:2022-03-07 Online:2022-04-22 Published:2022-05-01


The tryptophan (Trp)-derived plant secondary metabolites, including camalexin, 4-hydroxy-indole-3-carbonylnitrile, and indolic glucosinolate (IGS), show broad-spectrum antifungal activity. However, the distinct regulations of these metabolic pathways among different plant species in response to fungus infection are rarely studied. In this study, our results revealed that WRKY33 directly regulates IGS biosynthesis, notably the production of 4-methoxyindole-3-ylmethyl glucosinolate (4MI3G), conferring resistance to Alternaria brassicicola, an important pathogen which causes black spot in Brassica crops. WRKY33 directly activates the expression of CYP81F2, IGMT1, and IGMT2 to drive side-chain modification of indole-3-ylmethyl glucosinolate (I3G) to 4MI3G, in both Arabidopsis and Chinese kale (Brassica oleracea var. alboglabra Bailey). However, Chinese kale showed a more severe symptom than Arabidopsis when infected by Alternaria brassicicola. Comparative analyses of the origin and evolution of Trp metabolism indicate that the loss of camalexin biosynthesis in Brassica crops during evolution might attenuate the resistance of crops to Alternaria brassicicola. As a result, the IGS metabolic pathway mediated by WRKY33 becomes essential for Chinese kale to deter Alternaria brassicicola. Our results highlight the differential regulation of Trp-derived camalexin and IGS biosynthetic pathways in plant immunity between Arabidopsis and Brassica crops.

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