A natural variant of an MYC2 gene in soybean contributes to resistance against the common cutworm

Sep 29, 2026

This study investigates the genetic basis of soybean resistance to the common cutworm (CCW, Spodoptera litura). A key defense gene, GmMYC3, encoding an MYC2 transcription factor, is rapidly activated by jasmonic acid treatment and herbivore attack. GmMYC3 positively regulates biotic stress-related genes, inducing Kunitz-type trypsin inhibitors and modulating downstream GmWRKY56. Overexpression impairs larval digestion and delays larval and pupal development, with field tests supporting a defensive role. Population genetics suggests an elite GmMYC3 haplotype confers CCW resistance without reducing seed yield or quality.

LanguageEnglish

CategoryResearch & Report

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Pages11

Reading Time28 min

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RESEARCH ARTICLE AGRICULTURAL SCIENCES OPEN ACCESS A natural variant of an MYC2 gene in soybean contributes to resistance against the common cutworm Xiao Lia,1, Dezhou Hub,1, Zhongyi Yanga , Linyan Caia , Mengshan Zhanga , Hailun Liuc , Dongquan Guod , Shupeng Donga , Changyun Yanga , Fang Huanga , Deyue Yua,2, and Hui Wanga,2 Affiliations are included on p. 10. Edited by Sean Cutler, University of California Riverside, Riverside, CA; received December 5, 2024; accepted November 10, 2025 Herbivory is destructive for crop production in many regions worldwide. The induced plant response to herbivores promotes resistance; therefore, characterizing the mechanisms underlying natural host resistance is highly important. However, the genetic components of resistance to herbivores in the staple food crop soybean remain elusive. Here, a key defense gene, GmMYC3, was identified via joint linkage and association mapping in soybean. GmMYC3 encodes an MYC2 transcription factor that is rapidly activated after jasmonic acid treatment or herbivore attack and confers resistance to a major pest, the common cutworm (CCW), in soybean. GmMYC3 positively regulates multiple biotic stress-related genes, among which GmMYC3 triggers high expression of Kunitz-type trypsin inhibitors alongside its homolog GmMYC1 and downstream GmWRKY56. GmMYC3 overexpression results in massive accumulation of trypsin inhibitors in soybean leaves, interferes with the protein digestion and absorption function in larvae that are fed these leaves, and retards larval and pupal development of the CCW. The results of the field tests ofthe transgenic plants corroborate the defense role of GmMYC3. Evolutionary and population genetic analyses suggest that the elite haplotype of GmMYC3 contributes to resistance against the CCW without significant reduction in seed yield and quality. Notably, this haplotype appears at a low frequency in domesticated germplasms. This study sheds light on the molecular mechanism underlying plant resistance to the CCWand provides potentially valuable resources for breeding soybean plants with elevated resistance against this pest. GmMYC3 | haplotype | insect resistance | trypsin inhibitor | soybean In nature, plants and herbivorous pests have been engaged in endless cycles of attack and counterattack for millions of years (1, 2). During this process, herbivores have developed various abilities to take food from plants, and in turn, the sessile nature of plants forces them to develop complex defensive systems to cope with the threat of phytophagous insects, such as antibiosis, which causes abnormal insect development, and antixenosis, which repels herbivores from their host plants (3, 4). In agriculture, pest pressure on crops is intensifying because of ongoing climate change, which includes rising nighttime temperatures and decreasing frost day frequencies (5). The identification of endogenous resistance genes in plants is highly important for the breeding of insect-resistant crops. Soybean (Glycine max) is an economically important crop cultivated worldwide that provides nutrients for humans and livestock, such as high-quality protein and abundant oils. Owing to its polyphagous characteristics and rapid reproduction, the common cutworm (CCW, Spodoptera litura Fabricius) is a major herbivorous pest for soybean in many regions worldwide. For instance, in Asia, annual soybean yield losses caused by CCW infestation generally range from 10 to 20% and can exceed 50% in severe infestations (6–8) . To date, quantitative trait locus (QTL) mapping of soybean resistance to CCW has revealed two antibiosis QTLs, CCW-1 and CCW-2, and five antixenosis QTLs, qRslx1–qRslx4 and an unnamed QTL (3, 4, 9, 10). The positions ofCCW-1 and CCW-2 are similar to those of qRslx1 and the unnamed QTL, respectively, and they are located on chromosome 7. In addition, several QTLs for resistance to other insects have been detected on chromosome 7, including two c

FAQs

What gene is identified as a key defense factor against the common cutworm in soybean?

The key defense gene is GmMYC3, which encodes an MYC2 transcription factor activated by jasmonic acid treatment and herbivore attack.

How does GmMYC3 enhance resistance in soybean?

GmMYC3 positively regulates biotic stress-related genes, triggering Kunitz-type trypsin inhibitors and influencing downstream gene expression such as GmWRKY56, which interferes with insect protein digestion.

What do the field tests and population genetic analyses suggest about GmMYC3?

Field tests of transgenic plants corroborate the defensive role of GmMYC3. Evolutionary and population genetic analyses indicate an elite GmMYC3 haplotype contributes to CCW resistance without significant reduction in seed yield and quality.

Sep 29, 2026

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