3.5 Identification of AS events and fusion genes
AS serves as an important regulatory mechanism to fine-tune plant response to environmental stimuli by producing diverse transcripts. In this study, a total of 11,793 AS events including seven AS types were detected (Supplementary Figure 4). A3 and A5 were the dominant types of AS events, accounting for 43.44% and 38.86%, respectively (Figure 3C). Differential AS events were identified by calculating PSI (Supplementary Table 3). A total of 158 differential AS events were induced by GSB pathogen infection in Payzawat, which were generated by 48 annotated genes and 80 novel genes. Moreover, 117 differential AS events produced by 59 annotated genes and 46 novel genes were identified in GSB pathogen inoculated PI511890. KEGG enrichment analysis showed that the genes involved in differential AS events of Payzawat were significantly enriched in pathways related to carbohydrate metabolism, including glyoxylate and dicarboxylate metabolism, ascorbate and aldarate metabolism, and pyruvate metabolism. The pathway of RNA transport was significantly enriched for the genes involved in differential AS events in PI511890 (Supplementary Table 4). These results suggested that AS events participate in the defense responses to GSB pathogen infection in melon and exhibit significant differences between Payzawat and PI511890.
The candidate fusion genes were identified for each sample (Figure 3D). A total of 137 and 104 fusion genes were identified in the control groups of Payzawat and PI511890, respectively. After GSB pathogen infection, 129 and 118 fusion candidates were identified in Payzawat and PI511890, respectively. No significant differences were observed for the number and functional annotation of the fusion genes between the treatment and control groups. These results demonstrated that the fusion genes are probably not involved in the defense response to GSB.