Transcriptome analysis and characterization of cathepsin B-like protein in Melanaphis sorghi in response to resistant...

The sorghum aphid (Melanaphis sorghi), a phloem-feeding insect, is a major pest affecting sorghum production. Despite advances in understanding plant resistance mechanisms, the molecular responses of aphids to resistant host plants remain poorly characterized. Here, we aimed to elucidate transcriptional changes in sorghum aphids feeding on the resistant sorghum variety HN16 and to identify key aphid regulatory genes involved in host adaptation. RNA-seq analysis identified 1,388 differentially expressed genes (DEGs) in aphids feeding on HN16. Expression profiling revealed coordinated regulation of genes involved in apoptosis and detoxification. Through weighted gene co-expression network analysis (WGCNA), 10 candidate response genes were identified. Notably, knockdown of the DEG MsCathB1, encoding a cathepsin B-like protease, significantly impaired aphid fitness on resistant plants. Functionally, MsCathB1 also suppressed cryptogein-induced plant cell death and hydrogen peroxide accumulation. These findings suggest that sorghum aphid responses to host resistance are closely linked to apoptosis-related pathways, and that MsCathB1 may function as a virulence effector modulating both aphid performance and plant immunity. This work provides new insights into aphid-host interactions and supports the development of RNAi-based strategies for aphid control.

The online version contains supplementary material available at 10.1007/s11032-026-01670-9.