Aphid-Responsive Defense Networks in Hybrid Switchgrass

Authors

Kyle G. Koch, University of Nebraska - LincolnFollow
Nathan A. Palmer, Wheat, Sorghum, and Forage Research Unit, USDA-ARS & University of Nebraska - LincolnFollow
Teresa Donze-Reiner, West Chester University of Pennsylvania, West ChesterFollow
Erin D. Scully, Stored Product Insect and Engineering Research Unit, USDA-ARSFollow
Javier Seravalli, University of Nebraska-LincolnFollow
Keenan Amundsen, University of Nebraska-LincolnFollow
Paul Twigg, University of Nebraska at KearneyFollow
Joe Louis, University of Nebraska-LincolnFollow
Jeffrey D. Bradshaw, University of Nebraska-LincolnFollow
Tiffany Marie Heng-Moss, University of Nebraska - LincolnFollow
Gautam Sarath, Wheat, Sorghum, and Forage Research Unit, USDA-ARS & University of Nebraska - LincolnFollow

Document Type

Article

Date of this Version

2020

Citation

Koch KG, Palmer NA, Donze-Reiner T, Scully ED, Seravalli J, Amundsen K, Twigg P, Louis J, Bradshaw JD, Heng-Moss TM and Sarath G (2020) Aphid-Responsive Defense Networks in Hybrid Switchgrass. Front. Plant Sci. 11:1145. doi: 10.3389/fpls.2020.01145

Abstract

Aphid herbivory elicits plant defense-related networks that are influenced by host genetics. Plants of the upland switchgrass (Panicum virgatum) cultivar Summer can be a suitable host for greenbug aphids (Schizaphis graminum; GB), and yellow sugarcane aphids (Sipha flava, YSA), whereas the lowland cultivar Kanlow exhibited multi-species resistance that curtails aphid reproduction. However, stabilized hybrids of Summer (♀) x Kanlow (♂) (SxK) with improved agronomics can be damaged by both aphids. Here, hormone and metabolite analyses, coupled with RNA-Seq analysis of plant transcriptomes, were utilized to delineate defense networks induced by aphid feeding in SxK switchgrass and pinpoint plant transcription factors (TFs), such as WRKYs that potentially regulate these responses. Abscisic acid (ABA) levels were significantly higher in GB infested plants at 5 and 10 days after infestation (DAI). ABA levels were highest at 15DAI in YSA infested plants. Jasmonic acid levels were significantly elevated under GB infestation, while salicylic acid levels were signifi40cantly elevated only at 15 DAI in YSA infested plants. Similarly, levels of several metabolites were altered in common or specifically to each aphid. YSA infestation induced a significant enrichment of flavonoids consistent with an upregulation of many genes associated with flavonoid biosynthesis at 15DAI. Gene co-expression modules that responded singly to either aphid or in common to both aphids were differentiated and linked to specific TFs. Together, these data provide important clues into the interplay of metabolism and transcriptional remodeling accompanying defense responses to aphid herbivory in hybrid switchgrass.