A triple mutant of MYC2, MYC3, and MYC4 transcription factors is devoid of glucosinolates and more sensitive to attack by a generalist insect. These MYCs physically interact with six MYB transcription factors (MYB28, MYB29, MYB34, MYB51, MYB76, and MYB122) and regulate both basal and inducible glucosinolate levels by directly activating the expression of glucosinolate biosynthesis genes. Arabidopsis thaliana plants fend off insect attack by constitutive and inducible production of toxic metabolites, such as glucosinolates (GSs). A triple mutant lacking MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that are known to additively control jasmonate-related defense responses, was shown to have a highly reduced expression of GS biosynthesis genes. The myc2 myc3 myc4 (myc234) triple mutant was almost completely devoid of GS and was extremely susceptible to the generalist herbivore Spodoptera littoralis. On the contrary, the specialist Pieris brassicae was unaffected by the presence of GS and preferred to feed on wild-type plants. In addition, lack of GS in myc234 drastically modified S. littoralis feeding behavior. Surprisingly, the expression of MYB factors known to regulate GS biosynthesis genes was not altered in myc234, suggesting that MYC2/MYC3/MYC4 are necessary for direct transcriptional activation of GS biosynthesis genes. To support this, chromatin immunoprecipitation analysis showed that MYC2 binds directly to the promoter of several GS biosynthesis genes in vivo. Furthermore, yeast two-hybrid and pull-down experiments indicated that MYC2/MYC3/MYC4 interact directly with GS-related MYBs. This specific MYC–MYB interaction plays a crucial role in the regulation of defense secondary metabolite production and underlines the importance of GS in shaping plant interactions with adapted and nonadapted herbivores.
Arabidopsis Basic Helix-Loop-Helix Transcription Factors MYC2, MYC3, and MYC4 Regulate Glucosinolate Biosynthesis, Insect Performance, and Feeding Behavior[W][OPEN]
Fabian Schweizer,Patricia Fernández-Calvo,Mark Zander,Mónica Díez-Díaz,Sandra Fonseca,G. Glauser,M. Lewsey,J. Ecker,R. Solano,P. Reymond
Published 2013 in The Plant Cell
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- Publication year
2013
- Venue
The Plant Cell
- Publication date
2013-08-01
- Fields of study
Biology, Medicine, Environmental Science
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Semantic Scholar, PubMed
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