Sorghum bicolor transcriptome treated by Colletotrichum sublineolum. Sorghum bicolor

In eukaryotic organisms, alternative splicing (AS) is an important post-transcriptional mechanism to generate multiple transcript isoforms from a single gene. The protein variants translated from splicing isoforms may have altered molecular characteristics in signal transduction and metabolic activities. However, which transcript isoform will be translated into protein and the biological function of this resulting proteoform are yet to be identified. Sorghum is one of the five major cereal crops, however, its production is severely affected by fungal diseases such as anthracnose. The infection of sorghum plants by Colletotrichum sublineolum, greatly reduce production of grains and biomass. To further unravel the defense responses under fungal invasion, we applied the next-generation sequencing technology to C. sublineolum-inoculated sorghum seedlings compared with the mock-inoculated control. We have identified that AS regulation may function as important as traditional transcriptional control during responses to fungal infection. Furthermore, several genes involved in flavonoid and phenylpropanoid biosynthesis pathways were found to undergo multiple AS modifications. Further analysis demonstrated that non-conventional of both 5’ and 3’ splice sites were alternatively used in response to C. sublineolum infection. Splicing factors were also affected at both transcriptional and post-transcriptional levels. As a first transcriptome report related to C. sublineolum inoculation in sorghum, this study suggested that AS functions in parallel with transcriptional control, and participates in defense responses to fungal invasion in sorghum.