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Chemical defense against insects in Heterotheca subaxillaris and three Orobanchaceae species using exudates from trichomes
Author(s) -
Morimoto Masanori
Publication year - 2019
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.5395
Subject(s) - trichome , biology , botany , sesquiterpene , chemical defense , diterpene , sesquiterpene lactone , terpene , plant defense against herbivory , orobanchaceae , insect , chemical ecology , striga , terpenoid , labdane , herbivore , biochemistry , gene , germination
Abstract Background One of the roles of plant trichomes is thought to be reducing feeding damage from herbivores. Among trichomes, glandular trichomes play a role in chemical defense systems in plants by means of stored biologically active phytochemicals. These phytochemicals act as pest repellents. They show antimicrobial and insecticidal activities, and they have also been isolated and identified from wild plants. Results The Asteraceae species Heterotheca subaxillaris has many glandular trichomes on the leaf surface, and these contain sesquiterpene carboxylates, which show insect antifeedant activity. Because these sesquiterpene carboxylates are major constituents of glandular trichomes, they may act as a chemical defense in H. subaxillaris . The Orobanchaceae species Parentucellia viscosa also has many glandular trichomes on the leaf surface and produces an insect antifeedant clerodane‐type diterpene, kolavenic acid, in these trichomes. Additionally, two other Orobanchaceae species, Bellardia trixago and Parentucellia latifolia , also have many glandular trichomes, but the constituents of these glandular trichomes did not show biological activities against test insects. However, the seco‐labdane diterpene alcohol trixagol and its hemi‐malonate were major constituents in B. trixago , and these terpenes may act as physical defenses against herbivores by interfering with feeding due to their viscosity. Conclusion The secondary metabolites from glandular trichomes of H. subaxillaris and P. viscosa showed insect antifeedant activity, and these secondary metabolites were presumed to act as chemical defenses for these plant species. On the other hand, non‐biologically active secondary metabolites produced by two other Orobanchaceae, B. trixago and P. latifolia , were presumed to act as physical defenses due to their viscosity. Defense systems such as these may be applicable to new crop breeding to enhance protection against insect pests. © 2019 Society of Chemical Industry