Discovery of protein interactors of SUGARWINs in Saccharum officinarum using cDNA library screening

Sugarcane holds considerable commercial significance due to its role as the primary source of sugar and its potential as a global biofuel resource. Fungal pathogens and insect pests present significant challenges to the cultivation of this crop, leading to substantial reductions in crop yield and sugar recovery. In response to pathogen infection, plants initiate their defense mechanisms, which involve the upregulation of pathogenesis-related proteins such as chitinase, glucanase, and chitosanase. SUGARWINs refer to a group of PR-4 proteins that are associated with the defense mechanisms of sugarcane against phytopathogens. Their gene expression is induced in response to wounds caused by Diatraea saccharalis larvae and diseases caused by fungal pathogens such Colletothricum falcatum and Fusarium verticillioides . We report the finding of some other proteins that interact with SUGARWINs and may also have a role in the defense against fungal diseases. The sugarcane cDNA library was screened against SUGARWIN1 and SUGARWIN2 proteins to find possible interactors. A strong interaction of both SUGARWIN1 and SUGARWIN2 was observed with oxygen evolving enhancer protein 1 and synaptotagmin 1. These interactions were further validated by BiFC (biomolecular fluorescence complementation) assay. For further molecular characterization, subcellular localization studies of SUGARWINs and interactor proteins were conducted by translational fusion with green fluorescent protein.