Transcriptomic insights into perennial sorghum resistance to sugarcane aphids

Perennial crops, compared to annual cereals, offer multiple advantages that enhance crop resilience and promote sustainable agricultural practices such as low economic input, better soil health, increased carbon sequestration, etc. Sorghum (Sorghum bicolor), one of the top five cereals grown in the world, is currently under threat from sugarcane aphid (SCA; Melanaphis sacchari). In this study, we explored the molecular and genetic mechanisms that mediate the interaction between SCA and perennial sorghum (Sorghum bicolor x Sorghum halepense).

We employed the use of RNA-sequencing to investigate the transcriptomic responses of perennial sorghum genotypes with varying resistance levels to SCA infestation, aiming to identify key factors underlying resistance at early (6 and 24 h post-infestation) and late (7 d post infestation) time points. Temporal transcriptomic profiling revealed that SCA infestation triggered distinct changes in the expression levels of genes associated with various defense mechanisms in the sorghum genotypes. We identified 10,620 differentially expressed genes across early and late time points and highlighted key regulators of plant defense mechanisms. Weighted co-expression network analysis revealed that aphid infestation altered expression levels of genes corresponding to different biological and metabolic processes. Compared to the control and SCA-susceptible perennial sorghum plants, SCA feeding significantly induced the expression of genes related to the production of reactive oxygen species (ROS), death acids, cell wall modifications, callose synthesis, and defense-related phytohormones in SCA-resistant perennial sorghum line. Increased expression of various transcription factors (TFs) such as bHLH, NAC, and MYB were also observed uniquely in the SCA-resistant genotype.

In summary, our results suggest that the SCA-resistant sorghum perennial plants were better adapted to activate defense signaling mechanisms to curb SCA infestation. By identifying novel sources of perennial sorghum resistance to SCA, our findings contribute to advancing sorghum breeding programs, ultimately enhancing crop resilience and productivity.