Transcriptional Insights into the Sugarcane- Sorghum mosaic virus Interaction

Mosaic disease is a major viral disease that severely compromises sugar content and cane production. Among mosaic disease pathogens, Sorghum mosaic virus (SrMV) is the most prevalent one. To better understand the interaction mechanism between sugarcane and SrMV, samples of SrMV-infected and virus-free leaves of sugarcane cultivar ROC22 were deep sequenced and the sequencing data was confirmed by qRT-PCR. In total, 89,338 unigenes, 481 differentially expressed unigenes and 51 homologous sequences of Potyvirus host interactor (PHI) genes were obtained. The RNA-seq data implied that, the increase of SrMV replication from endoplasmic reticulum (ER) to chloroplast led to chloroplasts damage, following the initiation of differential expression of genes related to Ca2 +, ROS, cytokinin, auxin, and ethylene signaling, and also the transcription of some defense related genes. Among 51 PHIs, the upregulation of a calmodulin-related protein gene and an ethylene-inducible transcription factor gene in two SrMV-resistant and two SrMV-susceptible sugarcane cultivars under SrMV infection suggests that these two genes could be used as potential gene knockout targets for creating SrMV incompatible germplasm. Besides, based on its inverse expression pattern in the SrMV-resistant and -susceptible sugarcane cultivars, genes encoding heat shock protein 70, chloroplastic rieske Fe/S protein, reticulon homology domain protein and salicylic acid binding protein 3 might be used as the potential markers for identifying the resistance or susceptibility of sugarcane materials to SrMV. This study should help to understand the molecular mechanisms underlying SrMV-resistance of sugarcane cultivars.