|Barros-Rios, Jaime -|
|Malvar, Rosa -|
|Jung, Hans Joachim|
|Santiago, Rogelio -|
Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 5, 2011
Publication Date: April 1, 2011
Repository URL: http://hdl.handle.net/10113/49266
Citation: Barros-Rios, J., Malvar, R.A., Jung, H.G., Santiago, R. 2011. Cell wall composition as a maize defense mechanism against corn borers. Phytochemistry. 72(4-5):365-371. Interpretive Summary: Corn borer insect larvae are important economic pests for corn production in both the United States and southern European countries. While corn borers can be controlled using GMO technology, non-GMO forms of control would offer an additional method more acceptable to a segment of the public. Some progress has been made through traditional breeding to reduce corn borer damage. This study examined the role that plant cell wall (dietary fiber) chemistry plays as a resistance mechanism against corn borers in a set of non-GMO resistant and susceptible corn lines. It was found that resistant corn lines have more cell wall material in stem tissues and that these cell walls have a different carbohydrate makeup than observed in susceptible corn lines. Also, the resistant corn lines have more chemical cross linking between cell wall components. However, the presence of this increased cross linking does not reduce the digestibility of the cell wall material by the microorganisms found in the rumen of cattle. These results indicate that corn breeders could focus their selection programs on these cell wall traits, thereby avoiding the need to actually expose plants to corn borers in order to test for resistance, saving both time and money. Such a selection program would yield non-GMO corn lines with corn borer resistance and without reducing digestibility of corn stover, an important livestock feed.
Technical Abstract: European and Mediterranean corn borers are two of the most economically important insect pests of maize in North America and southern Europe, respectively. Cell wall structure and composition were evaluated in pith and rind tissues of diverse inbred lines as possible corn borer resistance traits. Cell wall polysaccharide and lignin concentration and composition, cell wall bound forms of hydroxycinnamic acids, and 24-h and 96-h in vitro rumen degradabilities were measured. Results from the analysis of pith and rind tissues were similar, with correlations between tissues higher than 60%. As expected, most of the cell wall components were found at higher concentration in the rind than in the pith, with the exception of pectic sugars and total diferulates. Pith of resistant inbred lines had significantly higher concentrations of total cell wall material than susceptible inbred lines, indicating that thickness of cell walls could be the initial barrier against corn borer larvae attack. Higher concentrations of xylose and 8-O-4' diferulate esters were found in resistant inbreds. Stem tunneling by corn borers was negatively correlated with concentrations of 8-5'b and 5-5' diferulates and p-coumarate esters. Degradability of cell wall polysaccharides was lower in rind than pith. Neither 24- nor 96-h in vitro rumen degradabilities were correlated with corn borer damage. Cell wall concentration, polysaccharide composition, and cross linking by diferulates appear to be possible mechanisms of corn borer resistance.