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Silencing Brassinosteroid Receptor BRI1 Impairs Herbivory‐elicited Accumulation of Jasmonic Acid‐isoleucine and Diterpene Glycosides, but not Jasmonic Acid and Trypsin Proteinase Inhibitors in Nicotiana attenuata
Author(s) -
Yang DaHai,
Baldwin Ian T.,
Wu Jianqiang
Publication year - 2013
Publication title -
journal of integrative plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.734
H-Index - 83
eISSN - 1744-7909
pISSN - 1672-9072
DOI - 10.1111/jipb.12035
Subject(s) - brassinosteroid , jasmonic acid , manduca sexta , biology , plant defense against herbivory , biochemistry , abscisic acid , brassinolide , botany , insect , salicylic acid , gene , arabidopsis , plant growth , mutant
The brassinosteroid (BR) receptor, BR insensitive 1 (BRI1), plays a critical role in plant development, but whether BRI1‐mediated BR signaling is involved in plant defense responses to herbivores was largely unknown. Here, we examined the function of BRI1 in the resistance of Nicotiana attenuata (Solanaceae) to its specialist insect herbivore Manduca sexta . Jasmonic acid (JA) and JA‐isoleucine conjugate (JA‐Ile) are important hormones that mediate resistance to herbivores and we found that after wounding or simulated herbivory NaBRI1 had little effect on JA levels, but was important for the induction of JA‐Ile. Further experiments revealed that decreased JAR (the enzyme for JA‐Ile production) activity and availability of Ile in NaBRI1 ‐silenced plants were likely responsible for the low JA‐Ile levels. Consistently, M. sexta larvae gained more weight on NaBRI1 ‐silenced plants than on the control plants. Quantification of insect feeding‐induced secondary metabolites revealed that silencing NaBRI1 resulted in decreased levels of carbon‐rich defensive secondary metabolites (hydroxygeranyllinalool diterpene glycosides, chlorogenic acid, and rutin), but had little effect on the nitrogen‐rich ones (nicotine and trypsin proteinase inhibitors). Thus, NaBRI1‐mediated BR signaling is likely involved in plant defense responses to M. sexta , including maintaining JA‐Ile levels and the accumulation of several carbon‐rich defensive secondary metabolites.