Skip to main content
eScholarship
Open Access Publications from the University of California

Maize death acids, 9-lipoxygenase-derived cyclopente(a)nones, display activity as cytotoxic phytoalexins and transcriptional mediators

  • Author(s): Christensen, SA
  • Huffaker, A
  • Kaplan, F
  • Sims, J
  • Ziemann, S
  • Doehlemann, G
  • Ji, L
  • Schmitz, RJ
  • Kolomiets, MV
  • Alborn, HT
  • Mori, N
  • Jander, G
  • Ni, X
  • Sartor, RC
  • Byers, S
  • Abdo, Z
  • Schmelz, EA
  • et al.
Abstract

Plant damage promotes the interaction of lipoxygenases (LOXs) with fatty acids yielding 9-hydroperoxides, 13-hydroperoxides, and complex arrays of oxylipins. The action of 13-LOX on linolenic acid enables production of 12-oxo-phytodienoic acid (12-OPDA) and its downstream products, termed "jasmonates." As signals, jasmonates have related yet distinct roles in the regulation of plant resistance against insect and pathogen attack. A similar pathway involving 9-LOX activity on linolenic and linoleic acid leads to the 12-OPDA positional isomer, 10-oxo-11-phytodienoic acid (10-OPDA) and 10-oxo-11-phytoenoic acid (10-OPEA), respectively; however, physiological roles for 9-LOX cyclopentenones have remained unclear. In developing maize (Zea mays) leaves, southern leaf blight (Cochliobolus heterostrophus) infection results in dying necrotic tissue and the localized accumulation of 10-OPEA, 10-OPDA, and a series of related 14- and 12-carbon metabolites, collectively termed "death acids." 10-OPEA accumulation becomes wound inducible within fungal-infected tissues and at physiologically relevant concentrations acts as a phytoalexin by suppressing the growth of fungi and herbivores including Aspergillus flavus, Fusarium verticillioides, and Helicoverpa zea. Unlike previously established maize phytoalexins, 10-OPEA and 10-OPDA display significant phytotoxicity. Both 12-OPDA and 10-OPEA promote the transcription of defense genes encoding glutathione S transferases, cytochrome P450s, and pathogenesis-related proteins. In contrast, 10-OPEA only weakly promotes the accumulation of multiple protease inhibitor transcripts. Consistent with a role in dying tissue, 10-OPEA application promotes cysteine protease activation and cell death, which is inhibited by overexpression of the cysteine protease inhibitor maize cystatin-9. Unlike jasmonates, functions for 10-OPEA and associated death acids are consistent with specialized roles in local defense reactions.

Many UC-authored scholarly publications are freely available on this site because of the UC Academic Senate's Open Access Policy. Let us know how this access is important for you.

Main Content
Current View