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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #344962
Title: Evaluation of greenbug and yellow sugarcane sphid feeding behavior on resistant and susceptible switchgrass cultivars

Author
item KOCH, KYLE - University Of Nebraska
item DONZE-REINER, TERESA - West Chester State University
item BAIRD, LISA - University Of San Diego
item Sarath, Gautam
item BRADSHAW, JEFFREY - University Of Nebraska
item HENG-MOSS, TIFFANY - University Of Nebraska

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/2018
Publication Date: 9/1/2018
Publication URL: http://handle.nal.usda.gov/10113/6082497
Citation: Koch, K.G., Donze-Reiner, T., Baird, L.M., Sarath, G., Bradshaw, J.D., Heng-Moss, T. 2018. Evaluation of greenbug and yellow sugarcane sphid feeding behavior on resistant and susceptible switchgrass cultivars. BioEnergy Research. 11:480-490. https://doi.org/10.1007/s12155-018-9914-3.
DOI: https://doi.org/10.1007/s12155-018-9914-3

Interpretive Summary: Switchgrass is an emerging biofuel crop that can be attacked by different insects. In turn, insect herbivores can significantly limit biomass yields by taking up nutrients needed for plant growth. Aphids are small insects that feed on the nutrients transported within plants and can inflict substantial damage to the host plant. Aphids frequently vector viruses that infect and further compromise plant growth. By discovering switchgrass plants that are resistant to aphids, plant breeders can improve switchgrass germplasm to become less impacted by aphid herbivory. Different methods can be utilized to discover plant resistance and resistance mechanisms to aphids. In this study a protocol called electrical penetration graph was first used to study defense mechanisms in diverse switchgrasses. Results indicated that the cultivar Kanlow was resistant to two aphids, namely greenbugs and yellow sugarcane aphids, whereas the cultivars Summer and KxS were susceptible to both. Microscopy of leaves, and gene-expression analyses were used to further understand defense mechanisms. The discovery of broad resistance to aphids in Kanlow plants suggests that Kanlow can be used to improve aphid resistance in future switchgrass cultivars.

Technical Abstract: Switchgrass (Panicum virgatum L.) is an emerging biofuel crop that serves as host for aphids. To discern the effects of plant age and possible resistance mechanisms, the feeding behavior of greenbugs (Schizaphis graminum Rondani.) and the yellow sugarcane aphid (Sipha flava Forbes.) was monitored on three diverse switchgrasses by the electrical penetration graph (EPG) technique. Callose deposition and genes associated with callose metabolism were also analyzed to discern their association with plant resistance. There was a strong host effect on greenbugs feeding on lowland cultivar Kanlow at the V3 stage of development, as compared to the greenbug-susceptible upland cultivar Summer and plants derived from Kanlow (') × Summer (') (K×S) crosses. These data confirmed that Kanlow at the V3 stage had antibiosis to greenbugs, which was absent in the Summer and K×S plants. In contrast, similar effects were not observed for yellow sugarcane aphids, excluding significant differences in the time to first probe on Kanlow plants at the V1 stage and reduction in time spent on pathway processes on Kanlow plants at the V3 stage. These data demonstrated that Kanlow plants may have multiple sources of resistance to the two aphids, and possibly some were phloem based. Microscopy of leaf sections stained with aniline blue for callose was suggestive of increased callose deposition in the sieve elements in Kanlow plants relative to Summer and K×S plants. RT-qPCR analysis of several genes associated with callose metabolism in infested plants was equivocal. Overall, these studies suggest the presence of multiple defense mechanisms against aphids in Kanlow plants, relative to Summer and K×S plants.