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An investigation of chinch bug, Blissus occiduus Barber resistance in warm -season grasses and enzymatic responses in plants challenged by phloem feeding insects
Plant resistance to insects offers an ideal pest management approach for both agronomically and horticulturally important crops because it is effective, economical, and environmentally responsible. This research evaluated warm-season turfgrasses for resistance to the western chinch bug, Blissus occiduus Barber, explored changes in peroxidase activity in resistant turfgrasses, and characterized the expression of a peroxidase gene involved in the defense response of resistant and susceptible sorghum Sorghum bicolor (L.) Moench to the greenbug, Schizaphis graminum (Rondani). Based on damage ratings the zoysiagrasses 'Diamond', 'Zoro', and 'Emerald' and the bermudagrass 'Mini Verde' were characterized as moderately resistant to B. occiduus, whereas the zoysiagrasses 'Zenith', 'Meyer', and 'Crowne' were highly to moderately susceptible to B. occiduus feeding. The zoysiagrass 'DeAnza' and bermudagrasses 'Tifway 419' and 'Tifsport' were categorized as moderately susceptible to chinch feeding. Levels of tolerance, antibiosis, and antixenosis in buffalograsses and zoysiagrasses cultivars were determined through choice and no-choice studies. The buffalograsses 184 and PX3-5-1 were characterized as tolerant, while Prestige and 196 exhibited both tolerance and antixenosis. Among the zoysiagrasses, Zoro was tolerant and Emerald displayed both tolerance and low levels of antixenosis. No antibiosis was present in any of the grasses tested. Increased peroxidase activity was observed in the buffalograss PX3-5-1 and zoysiagrass Zoro in response to B. occiduus feeding. This did not occur in any other turfgrass cultivar tested. Concurrent research identified and sequenced a differentially expressed peroxidase in the isozyme profile of resistant sorghum. Quantitative real-time PCR was employed to measure changes in peroxidase gene expression of greenbug-resistant (Cargill 607E) and---susceptible (Garst 5715) sorghum cultivars over time. Similar trends in gene activity were observed in 607E and 5715 at four and eight days after greenbug introduction. At 12 days, however, there was a significant increase in peroxidase gene expression in the greenbug-resistant sorghum 607E. This research provides important information on the categories and mechanisms of chinch bug resistance in warm-season turfgrasses. It also offers valuable insights into how these plants defend themselves against insect feeding.
Eickhoff, Thomas E, "An investigation of chinch bug, Blissus occiduus Barber resistance in warm -season grasses and enzymatic responses in plants challenged by phloem feeding insects" (2007). ETD collection for University of Nebraska - Lincoln. AAI3242150.