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Sorghum-Sugarcane Aphid Interactions: Multi-Omic Approaches to Elucidate Plant Defense Against Sap-Feeding Insects
Abstract
Sorghum (Sorghum bicolor L. Moench) is an important crop grown worldwide due to its multiple uses and adaptability to different environments. It serves as an excellent food source and is also used for biofuel production and livestock feed. However, due to the outbreak of sugarcane aphid (SCA; Melanaphis sacchari) on sorghum in 2013, it has suffered yield losses of >50% in subsequent years. Different sources of SCA resistant sorghum have been identified but the mechanism of resistance against SCA is not known. The current study aimed to comprehend the defense mechanisms used by sorghum plants to counter aphid infestation, laying a foundation for the development of sustainable pest control. In this study, we used the previously identified SCA-resistant line SC265, SCAsusceptible line SC1345, and an elite sorghum male parental line RTx430 (reference line). We found that greenbugs (Schizaphis graminum)-infested sorghum activates plant defenses via phytohormones and flavonoids and hampers the colonization of subsequent incoming SCA. Phytohormone analysis and bioassays have revealed that jasmonic acid (JA) has a dual role in regulating sorghum defense against SCA; it contributes to initial aphid deterrence, while at later stages, it facilitates aphid feeding and colonization. Interestingly, JA facilitated aphid feeding and colonization on sorghum plants is mediated by altering sugar metabolism. Transcriptional response of sorghum to SCA feeding at early time points and for prolonged feeding suggested that aphid feeding modulates sorghum defenses by regulating genes corresponding to plant defenses, sucrose metabolism, callose formation, phospholipases, and proteinase inhibitors. Overall, our transcriptomic results indicate that the SCA-resistant line is better adapted to activate early defense signaling mechanisms in response to SCA feeding. Lastly, we also performed lipid profiling of the SCA-resistant and susceptible lines and uncovered that SCA feeding drastically reduced the overall lipids in the SCA-resistant line. Our results also suggest that SCA feeding induced the accumulation of secondary messenger lipids such as diacylglycerol and phosphatidic acid, indicating their potential role in modulating plant defenses. Collectively, results from this research elucidated sorghum defense mechanisms against sap-feeding aphids and identified new gene targets for pest control.
Subject Area
Entomology|Plant Pathology
Recommended Citation
Puri, Heena, "Sorghum-Sugarcane Aphid Interactions: Multi-Omic Approaches to Elucidate Plant Defense Against Sap-Feeding Insects" (2023). ETD collection for University of Nebraska-Lincoln. AAI30488957.
https://digitalcommons.unl.edu/dissertations/AAI30488957