Transcriptional Regulation of SugarCane Response to Sporisorium scitamineum : Insights from Time-Course Gene Coexpression and Ca 2+ Signaling.

Sugarcane response to Sporisorium scitamineum is determined by multiple major genes and numerous microeffector genes. Here, time-ordered gene coexpression networks were applied to explore the interaction between sugarcane and S. scitamineum . Totally, 2459 differentially expressed genes were identified and divided into 10 levels, and several stress-related subnetworks were established. Interestingly, the Ca 2+ signaling pathway was activated to establish the response to sugarcane smut disease. Accordingly, two CAX genes ( ScCAX2 and ScCAX3 ) were cloned and characterized from sugarcane. They were significantly upregulated under ABA stress but inhibited by MeJA treatment. Furthermore, overexpression of ScCAX2 and ScCAX3 enhanced the susceptibility of transgenic plants to the pathogen infection, suggesting its negative role in disease resistance. A regulatory model for ScCAX genes in disease response was thus depicted. This work helps to clarify the transcriptional regulation of sugarcane response to S. scitamineum stress and the function of the CAX gene in disease response.