Juice chemical properties of 24 sorghum cultivars under varying levels of sugarcane aphids (Melanaphis sacchari) infestation

Authors: Knoll, Joseph - Joe; Uchimiya, Sophie; Harris-Shultz, Karen

Submitted to: Arthropod-Plant Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2021
Publication Date: 9/6/2021
Citation: Knoll, J.E., Uchimiya, S., Harris-Shultz, K. 2021. Juice chemical properties of 24 sorghum cultivars under varying levels of sugarcane aphids (Melanaphis sacchari) infestation. Arthropod-Plant Interactions. 15(5):707-719. https://doi.org/10.1007/s11829-021-09855-z.
DOI: https://doi.org/10.1007/s11829-021-09855-z

Interpretive Summary: Sugarcane aphid has become a significant insect pest of sorghum in the United States in recent years, causing yield reduction in all types of sorghum. While some resistant or tolerant sorghum accessions have been identified, the biochemical basis of sugarcane aphid resistance in sorghum is not well-characterized. The effects of sugarcane aphid damage on sweet sorghum stem juice quality have also not been well studied. Our previous research identified the presence of polyphenols and trans-aconitic acid in sweet sorghum stem juice, with particularly high levels of these compounds in the aphid-resistant accession ‘No. 5 Gambela.’ In the current study, data from 24 cultivars grown in seven environments were analyzed in order to identify potential relationships between juice chemical properties and aphid damage ratings. In four environments with high aphid population pressure (=100 aphids/leaf), it was observed that the most resistant cultivars had higher trans-aconitic acid in their juice than the more susceptible cultivars. Fluorescence and electrochemical properties related to the presence of polyphenols showed similar relationships with aphid damage. trans-Aconitic acid appears to function as a general aphid tolerance mechanism in sorghum, while the polyphenols found in No. 5 Gambela may further enhance the resistance of this cultivar.

Technical Abstract: Sugarcane aphid [Melanaphis sacchari (Zehntner)] has become a significant pest of sorghum [Sorghum bicolor (L.) Moench] in the United States in recent years, causing yield reduction in all types of sorghum. While some sources of host plant resistance or tolerance have been identified, the biochemical basis of sugarcane aphid resistance in sorghum is not well-characterized. The effects of sugarcane aphid damage on sweet sorghum juice quality have also not been well studied. Our previous research identified the presence of polyphenols and trans-aconitic acid in sweet sorghum juice, with particularly high levels of these compounds in the aphid-resistant landrace ‘No. 5 Gambela.’ In the current study, data from 24 cultivars grown in seven environments were analyzed in order to identify potential relationships between juice chemical properties and aphid damage ratings. In four environments with high aphid population pressure (=100 aphids/leaf), a significant negative correlation between trans-aconitate and aphid damage was observed, even after reanalyzing the data without the most extreme cultivar, No. 5 Gambela. Fluorescence and electrochemical properties related to the presence of polyphenols also showed correlations with aphid damage, but without No. 5 Gambela these associations became non-significant. trans-Aconitic acid appears to function as a general aphid tolerance mechanism in sorghum, at least among the cultivars in this study. The aromatic polyphenolic structures identified in No. 5 Gambela may further enhance the resistance of this cultivar.