Maize Plants Recognize Herbivore-Associated Cues from Caterpillar Frass
Caterpillar behaviors such as feeding, crawling, and oviposition are known to induce defenses in maize and other plant species. We examined plant defense responses to another important caterpillar behavior, their defecation. Fall armyworms (FAW, Spodoptera frugiperda), a major threat to maize (Zea mays), are voracious eaters and deposit copious amounts of frass in the enclosed whorl tissue surrounding their feeding site, where it remains for long periods of time. FAW frass is composed of molecules derived from the host plant, the insect itself, and associated microbes, and hence provides abundant cues that may alter plant defense responses. We observed that proteins from FAW frass initially induced wound-responsive defense genes in maize; however, a pathogenesis-related (pr) defense gene was induced as the time after application increased. Elicitation of pathogen defenses by frass proteins was correlated with increased herbivore performance and reduced fungal pathogen performance over time. These responses differ from the typical plant response to oral secretions of the FAW. The results pave the way for identification of protein molecule(s) from the excretion of an herbivore that elicits pathogen defense responses while attenuating herbivore defenses in plants.
KeywordsFrass Fall armyworm Maize
We thank Dr. Rebecca Boston for sending us antibody for Rip2 protein in maize. We also thank the insight of Nate McCarthey in Dr. Jim Tumlinson’s lab for the phytohormone analyses. We thank Dr. Elizabeth Bosak for letting us use the wounding tool. The author also acknowledges Dr. Kelli Hoover’s lab for help in quantifying RNA samples with Nanodrop (Thermo Fisher Scientific). We appreciate the comments of Dr SeungHo Chung in the preparation of this manuscript. We thank Susan Wolf at USDA-ARS (MSU), for providing the FAW eggs.
This work was supported by grants from USDA NIFA (2010-65105-20639 and 2011-67013-30352) awarded to D.S.L and G.W.F.
- Chen H, Gonzales-Vigil E, Wilkerson CG, Howe GA (2007) Stability of plant defense proteins in the gut of insect herbivores. Plant Physiol 143:1954–1967Google Scholar
- Chen H, Wilkerson CG, Kuchar JA, Phinney BS, Howe GA (2005) Jasmonate-inducible plant enzymes degrade essential amino acids in the herbivore midgut. Proc Natl Acad Sci USA 102:19237–19242Google Scholar
- Ritchie SW, Hanway JJ, Benson GO (1986) How a corn plant develops. Iowa State University of Science and Technology Cooperative Extension Service Special Report 48 (Revised), Ames, IA, U.S.A.Google Scholar
- Schoonhoven LM, van Loon JJA, Dicke M (2005) Insect-plant biology, 2nd edn. Oxford University Press, OxfordGoogle Scholar
- Shanmugam V, Ronen M, Shalaby S, Larkov O, Rachamim Y, Hadar R, Rose MS, Carmeli S, Horwitz BA, Lev S (2010) The fungal pathogen Cochliobolus heterostrophus responds to maize phenolics: novel small molecule signals in a plant-fungal interaction. Cell Microbiol 12:1421–1434CrossRefPubMedGoogle Scholar
- Van der Does D, Leon-Reyes A, Koornneef A, Van Verk MC, Rodengurg N, Pauwels L, Goossens A, Körbes AP, Memelink J, Ritsema T, Van Wees SCM, Pierterse CMJ (2013) Salicylic acid suppresses jasmonic acid signaling downstream of SCFCOI1-JAZ by targeting GCC promoter motifs via transcription factor ORA59. Plant Cell 25:744–761PubMedCentralCrossRefPubMedGoogle Scholar