Sugarcane is a Negative Regulator of Resistance to Pathogen Infection.

Calcium (Ca) is a second messenger in various physiological processes within plants. The significance of the Ca/H exchanger (CAX) has been established in facilitating Ca transport in plants; however, disease resistance functions of the gene remain elusive. In this study, we conducted sequence characterization and expression analysis for a sugarcane gene, (GenBank Accession Number: MW206380). In order to further investigate the disease resistance functions, this gene was then transiently overexpressed in leaves, which were subsequently inoculated with var. . Results showed that overexpression increased the susceptibility of to pathogen infection by regulating the expression of genes related to salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) pathways, suggesting its negative role in disease resistance. Furthermore, we genetically transformed the gene into and obtained three positive T generation lines. Interestingly, the symptomatology of transgenic plants was consistent with that of transient overexpression after pathogen inoculation. Notably, the JA content in transgenic overexpression lines was significantly higher than that in the wild-type. RNA-seq revealed that could mediate multiple signaling pathways, and the JA signaling pathway played a key role in modulating disease resistance. Finally, a regulatory model was depicted for the increased susceptibility to pathogen infection conferred by the gene. This study provides genetic resources for sugarcane molecular breeding and the research direction for plant genes.