|Arunkanth, Ankala -|
|Kelley, Rowena -|
|Rowe, Dennis -|
|Luthe, Dawn -|
Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 23, 2012
Publication Date: February 1, 2013
Citation: Ankala, A., Kelley, R.Y., Rowe, D.E., Williams, W.P., Luthe, D.S. 2013. Foliar herbivory triggers local and long distance defense responses in maize. Plant Science. 200:103-112. http://www.sciencedirect.com/science/article/pii/S0168945212002257. Interpretive Summary: Fall armyworm damage is a serious threat to late-planted corn in the southern United States. Genetic resistance to fall armyworm feeding has been identified by USDA-ARS scientists at Mississippi State. Germplasm lines with resistance have been developed and released. This investigation was undertaken to investigate the effects of genes associated with resistance to fall armyworm damage. The results indicated that when fall armyworm larvae fed on the leaves of resistant plants, genes associated with jasmonic acid biosynthesis were up-regulated in the plant whorl, but genes associated with ethylene perception and signaling were up-regulated in the roots. Foliar feeding by fall armyworm accompanied by changes in gene expression in the roots suggests profound long-distance signaling. Tissue-specific induction and suppression of jasmonic acid and ethylene signaling pathway genes provide a clue to their roles in plant resistance.
Technical Abstract: More evidence supporting the induction of defenses in belowground plant parts in response to aboveground herbivory and vice versa is being reported. However the genes and signaling molecules mediating such systemic induction are still not clearly established. In this study we performed comparative microarray analysis on maize whorl and root tissues in response to foliar feeding by fall armyworm (Spodoptera frugiperda) caterpillars. The results indicated that jasmonic acid (JA) biosynthesis genes were up-regulated in the whorl, whereas ethylene perception and signaling components were up-regulated in the roots. The transcript levels of many genes encoding proteins involved in direct defenses against herbivores were enhanced both in roots and leaves, but transcriptional factors and genes involved in various biosynthetic pathways were selectively down-regulated in the whorl. The results indicate that foliar herbivory by fall armyworm caterpillars results in changes in root gene expression pathways suggesting profound long distance signaling. Tissue specific induction and suppression of JA and ET signaling pathway genes provide a clue as to the role of JA and ethylene (ET) in mediating the signaling between the two distant tissue types eventually triggering defense responses in the roots in response to foliar herbivory.