Interplay of phytohormones facilitate sorghum tolerance to aphids

Authors

Sajjan Grover, University of Nebraska - LincolnFollow
Earl Agpawa, University of Nebraska - LincolnFollow
Gautam Sarath, United States Department of Agriculture -Agricultural Research ServiceFollow
Scott E. Sattler, University of Nebraska - LincolnFollow
Joe Louis, University of Nebraska–LincolnFollow

ORCID IDs

Sajjan Grover http://orcid.org/0000-0003-4391-0584

Gautam Sarath http://orcid.org/0000-0002-3145-9493

Scott E. Sattler http://orcid.org/0000-0002-6814-4073

Joe Louis http://orcid.org/0000-0001-7137-8797

Date of this Version

10-2020

Citation

Plant Molecular Biology (2020)

https://doi.org/10.1007/s11103-020-01083-y

Comments

U.S. government work

Abstract

Key message -- Interactions among phytohormones are essential for providing tolerance of sorghum plants to aphids.

Plant’s encounter with insect herbivores trigger defense signaling networks that fine-tune plant resistance to insect pests. Although it is well established that phytohormones contribute to antixenotic- and antibiotic-mediated resistance to insect pests, their role in conditioning plant tolerance, the most durable and promising category of host plant resistance, is largely unknown. Here, we screened a panel of sorghum (Sorghum bicolor) inbred lines to identify and characterize sorghum tolerance to sugarcane aphids (SCA; Melanaphis sacchari Zehntner), a relatively new and devastating pest of sorghum in the United States. Our results suggest that the sorghum genotype SC35, the aphid-tolerant line identified among the sorghum genotypes, displayed minimal plant biomass loss and a robust photosynthetic machinery, despite supporting higher aphid population. Phytohormone analysis revealed significantly higher basal levels of 12-oxo-phytodienoic acid, a precursor in the jasmonic acid biosynthesis pathway, in the sorghum SCA-tolerant SC35 plants. Salicylic acid accumulation appeared as a generalized plant response to aphids in sorghum plants, however, SCA feeding-induced salicylic acid levels were unaltered in the sorghum tolerant genotype. Conversely, basal levels of abscisic acid and aphid feeding-induced cytokinins were accumulated in the SCA-tolerant sorghum genotype. Our findings imply that the aphid-tolerant sorghum genotype tightly controls the relationship among phytohormones, as well as provide significant insights into the underlying mechanisms that contribute to plant tolerance to sap-sucking aphids.