Salicylic Acid, a Plant Hormone, Suppresses Phytophagous Insect Immune Response by Interrupting HMG-Like DSP1

Md Mahi Imam Mollah; Hyong Woo Choi; Inhwa Yeam; Je Min Lee; Yonggyun Kim

doi:10.3389/fphys.2021.744272

Salicylic Acid, a Plant Hormone, Suppresses Phytophagous Insect Immune Response by Interrupting HMG-Like DSP1

Front Physiol. 2021 Oct 4:12:744272. doi: 10.3389/fphys.2021.744272. eCollection 2021.

Authors

Md Mahi Imam Mollah¹, Hyong Woo Choi¹, Inhwa Yeam², Je Min Lee³, Yonggyun Kim¹

Affiliations

¹ Department of Plant Medicals, Andong National University, Andong, South Korea.
² Department of Horticulture and Breeding, Andong National University, Andong, South Korea.
³ Department of Horticultural Science, Kyungpook National University, Daegu, South Korea.

Abstract

Salicylic acid is a plant hormone that can mediate various plant physiological processes. Salicylic acid can bind to human high mobility group box 1 (HMGB1) and interrupt its role in mediating immune responses. Dorsal switch protein 1 (DSP1) is an insect homolog of HMGB1. In this study, a DSP1 (Se-DSP1) encoded in Spodoptera exigua, a phytophagous insect, was characterized, and its potential role in immune response was explored. Upon bacterial challenge, Se-DSP1 was localized in the nucleus and released into the hemolymph. The released Se-DSP1 could mediate both cellular and humoral immune responses by activating eicosanoid biosynthesis. Salicylic acid could bind to Se-DSP1 with a high affinity. The immune responses of S. exigua were significantly interrupted by SA feeding. Larvae reared on tomatoes with high endogenous SA levels became more susceptible to entomopathogens. Taken together, these results suggest a tritrophic defensive role of plant SA against phytophagous insects.

Keywords: HMGB1; eicosanoid; immunity; insect; salicylic acid.