Location: Chemistry Research Unit
Title: Maize kauralexins: insights into structure, function, and biosynthesis Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 5, 2013
Publication Date: N/A
Technical Abstract: Phytoalexins are a broad category of pathogen and insect-inducible biochemicals that locally protect plant tissues. Terpenoid phytoalexins have been extensively examined numerous crop plants but until recently were considered absent in maize (Zea mays). We discovered a series of acidic ent-kaurane-related diterpenoids, termed kauralexins, present in maize stem tissues challenged with European corn borer (Ostrinia nubilalis) larvae and fungal pathogens. Kauralexins accumulate to levels exceeding 100 mg g-1 FW and exhibit significant insect antifeedant and antimicrobial properties when tested in vitro. These activities and roles are also important to examine in vivo. The maize gene Anther ear 1(An1) encodes an ent-copalyl diphosphate synthase (ent-CPS) essential for normal levels of ent-kaurane derived gibberellin phytohormones. Mutantions in this gene, an1, result in a dwarf phenotype and flowers on typically pistillate ears. In contrast a gene encoding a second maize ent-CPS, termed An2, is highly inducible by fungal pathogens. We hypothesized that An2 is responsible for the rapid local accumulation of kauralexins following elicitation. Using a homozygous transposon insertion an2 mutant, we demonstrate that this type I diterpene synthase is required for the inducible biosynthesis and accumulation of kauralexins in maize. Resistance assays with insects and pathogens are currently ongoing to explore the predicted alterations in plant defense phenotype.