Plant Diversity ›› 2024, Vol. 46 ›› Issue (04): 519-529.DOI: 10.1016/j.pld.2024.03.004

• Articles • Previous Articles    

Salicylic acid positively regulates maize defenses against lepidopteran insects

Yohannes Besufekad Setotawa,b, Jing Lia,b, Jinfeng Qia,b, Canrong Maa,b, Mou Zhanga,b, Cuilian Huanga,b, Lei Wanga,b, Jianqiang Wua,b,c   

  1. a. Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China;
    b. CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China;
    c. State Key Laboratory of Plant Diversity and Specialty Crops, Beijing 100093, China
  • Received:2024-02-22 Revised:2024-03-12 Published:2024-07-29
  • Contact: Jianqiang Wu,E-mail:wujianqiang@mail.kib.ac.cn
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (U23A20199 (J.W.), 32302464 (C.M.)), the Postdoctoral Fellowship Program of CPSF (GZC20232764 (C. M.)), the Yunnan Revitalization Talent Support Program “Yunling Scholar” Project (J.W.), Yunnan Innovation Team Project (202105AE160013 (J.W.)), the Strategic Priority Research Program of Chinese Academy of Sciences (XDPB16 (J.W.)), the CAS “Light of West China” Program (J.Q.), the General and Key Project of Applied Basic Research Program of Yunnan (202201AS070053 (J.Q.)), the Special Research Assistant of Chinese Academy of Sciences (C.M.), and the Postdoctoral Directional Training Foundation of Yunnan Province (M.Z.).

Abstract: In response to insect attack, plants use intricate signaling pathways, including phytohormones, such as jasmonate (JA), ethylene (ET), and salicylic acid (SA), to activate defenses. Maize (Zea mays) is one of the most important staple food crops around the world. Previous studies have shown that the JA and ET signaling play important roles in maize defense against insects, but little is known about whether and how SA regulates maize resistance to insect herbivores. In this study, we ectopically expressed the NahG (salicylate hydroxylase) gene in maize plants (NahG maize) to block the accumulation of SA. It was found that compared with the wild-type (WT) maize, the NahG maize exhibited decreased resistance to the generalist insects Spodoptera litura and Spodoptera frugiperda and the specialist Mythimna separata, and the compromised resistance in the NahG maize was associated with decreased levels of defensive metabolites benzoxazinoids (Bxs) and chlorogenic acid (CA). Quantification of simulated S. litura feeding-induced JA, JA-isoleucine conjugate (JA-Ile), and ET in the WT and NahG maize indicated that SA does not regulate JA or JA-Ile, but positively controls ET. We provide evidence suggesting that the SA pathway does not crosstalk with the JA or the ET signaling in regulating the accumulation of Bxs and CA. Transcriptome analysis revealed that the bHLH, ERF, and WRKY transcription factors might be involved in SA-regulated defenses. This study uncovers a novel and important phytohormone pathway in maize defense against lepidopterous larvae.

Key words: Benzoxazinoids, Salicylic acid, Herbivory, Maize, Transcriptome