Induction, isolation and characterization of a hydroxyproline rich glycoprotein in pearl millet for protection against downy mildew disease

PhD ceremony: Mr. S. Neerakkal, 11.00 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Induction, isolation and characterization of a hydroxyproline rich glycoprotein in pearl millet for protection against downy mildew disease

Promotor(s): prof. J. Hille

Faculty: Mathematics and Natural Sciences

Pearl millet is an important grain grown and consumed mainly in Africa and India. One of the most serious threats affecting these plants is the downy mildew disease caused by the oomycete pathogen Sclerospora graminicola. The aim of the study of Sujeeth Neerakkal was to examine the role a specific protein, called hydroxyproline-rich glycoprotein (HRGP), plays in the defense of pearl millet against the downy mildew disease.

HRGP belongs to a class of proteins found in the cell wall of plants. Neerakkal isolated and studied the protein, mRNA and the gene coding for HRGP in pearl millet. During S. graminicola infection, induced accumulation at the mRNA and protein level of HRGP was observed in pearl millet. Under lab conditions (in vitro) he demonstrated that this protein gets cross-linked to form a network. A similar kind of network formation in the cell wall of pearl millet will stop the pathogen entry into pearl millet.

Furthermore, upon seed treatment of pearl millet using elicitors he observed an increase in the HRGP level. Thus pearl millet can be improved against the downy mildew disease by treating the seeds with elicitors of defense. The results are of importance for a better field management of downy mildew disease in pearl millet. In addition, biotechnological applications such as gene modifications for an increased HRGP content could improve pearl millet against the downy mildew disease.