Thionins (PR protein-13) mediate pearl millet downy mildew disease resistance

Abstract

Thionins (PR protein-13) are a class of Cys-rich polypeptides of about 5 kDa, and have revealed their role of the defense in pearl millet to Sclerospora graminicola. The purified 5 kDa thionins show a pI of 8.2 and have anti-mildew activity tested on S. graminicola. The high level of transcript expression of thionins in resistant compared to susceptible cultivars was observed. Immunofluorescence studies have shown intense fluorescence in epidermal regions, confirming its involvement in arresting pathogen ingress and in vascular regions, confirming its systemic translocation during interaction. Epidermal peeling of resistant cultivars showed that thionin protein was present in higher quantities at the papillar region of the cell wall in seedlings.