Oxidative responses of St. Augustinegrasses to feeding of southern chinch bug, Blissus insularis Barber.
Southern chinch bug, Blissus insularis Barber (Hemiptera: Blissidae), is a serious insect pest of St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze, a turfgrass commonly grown in the southeastern United States. Resistance to southern chinch bug has been identified in the polyploid St. Augustinegrass varieties 'Floratam' and 'FX-10', and the diploid 'Captiva'. However, southern chinch bug in Florida and elsewhere has overcome Floratam's resistance. This research investigated the potential role of selected plant oxidative enzymes in resistance/susceptibility to southern chinch bug in two polyploid varieties (FX-10 and Floratam) and two diploid varieties (Captiva and Palmetto). Oxidative enzyme activity was estimated spectrophotometrically from plant samples collected 1, 3, 5, and 8 days after southern chinch bug infestation and from uninfested control plants. Resistant FX-10 and Captiva had significantly higher peroxidase activity, while Captiva had significantly higher polyphenol oxidase activity 5 and 8 days after infestation compared to uninfested controls. FX-10 had higher lipoxygenase activity 3, 5, and 8 days after infestation compared to uninfested controls. Catalase activities did not differ between infested and control plants in any of the varieties tested. Native gels stained for peroxidase indicated that certain isozymes in FX-10 and Captiva were induced 5 and 8 days after infestation. Isozyme profiles of polyphenol oxidase and lipoxygenase did not differ between control and infested FX-10, Floratam, Captiva, and Palmetto. Potential mechanisms to explain the correlation of resistance to southern chinch bug in FX-10 and Captiva with higher activities of oxidative enzymes are discussed.
Rangasamy
Murugesan
M
Department of Entomology and Nematology, University of Florida, Gainesville, FL 32611, USA.
Rathinasabapathi
Bala
B
McAuslane
Heather J
HJ
Cherry
Ronald H
RH
Nagata
Russell T
RT
D000818:Animals; D002374:Catalase / Q000378:metabolism; D004156:Catechol Oxidase / Q000378:metabolism; D006430:Hemiptera / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D008084:Lipoxygenase / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D010572:Pest Control, Biological; D006109:Poaceae / Q000201:enzymology*; D020033:Protein Isoforms / Q000378:metabolism
D020033:Protein Isoforms; D010088:Oxidoreductases; D004156:Catechol Oxidase; D002374:Catalase; D008084:Lipoxygenase