|AVER'YANOV, A - Russian Academy Of Sciences|
|PASECHNIK, T - Russian Academy Of Sciences|
|LAPIKOVA, V - Russian Academy Of Sciences|
|ROMANOVA, T - Russian Academy Of Sciences|
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2017
Publication Date: 5/30/2017
Citation: Aver'Yanov, A.A., Pasechnik, T.D., Lapikova, V.P., Romanova, T.S., Baker, C.J. 2017. Systemic reduction of rice blast by means of photosensitizers. Frontiers in Plant Science. 64:543-552. 10.1134/s1021443717030037.
Interpretive Summary: Fungal diseases of crops cause major losses for farmers each year. Many of these diseases start by the germination of the fungal spore on the leaf surface. By learning to disrupt critical mechanisms that are involved in spore germination we could reduce the amount of disease. This study demonstrated that application of photosensitizers that increase reactive oxygen in older tissue can protect new tissue by inhibiting spore germination. This information will be of use to plant scientists who are devising new strategies to improve disease resistance in plants.
Technical Abstract: Acquired disease resistance of plants may be induced by exogenous reactive oxygen species or their sources. Certain compounds (photosensitizers) produce ROS at the expense of light energy. This study used photodynamic dyes bengal rose and methylene blue, which yield singlet oxygen, and mercaptopyridine-N-oxide, which yields a hydroxyl radical. The goal was to find out whether they can systemically protect rice (Oryza sativa L.) from blast caused by the fungus Magnaporthe oryzae Conouch et Kohn, and whether ROS is involved in the defense mechanisms. The tested compounds were placed on the 4th (uppermost) leaf. When the 5th leaf developed (in about 7 days) it was inoculated with virulent fungal strain. It was found that the chemical treatments altered the 4th leaf and reduced disease symptoms on the 5th leaf. Antioxidants combined with the tested substances compromised the disease control. Photosensitizers applied to the 4th leaf increased superoxide production (increased rate of hydrogen peroxide production) in drop diffusates from healthy and to a larger extent from subsequent infected 5th leaf. In these diffusates, fungitoxicity also increased, which was diminished by antioxidants added to the diffusates. It is suggested that the oxidative burst in the treated leaves induced the systemic acquired resistance whose accomplishment might include the secondary oxidative burst in systemic leaves suppressing the pathogen development.