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Title: Possible Contribution of Blast Spores to the Oxidative Burst in the Infection Droplet on Rice Leaf

Author
item AVERYANOV, A - MOSCOW RUSSIA
item PASECHNIK, T - MOSCOW RUSSUA
item LAPIKOVA, V - MOSCOW RUSSIA
item GAIVORONSKAYA, L - MOSCOW RUSSIA
item KUZNETSOV, VL - MOSCOW RUSSIA
item Baker, Con

Submitted to: Acta Phytopathologica and Entomolgica Hungarica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2007
Publication Date: 12/1/2007
Citation: Averyanov, A.A., Pasechnik, T.D., Lapikova, V.P., Gaivoronskaya, L.M., Kuznetsov, V.V., Baker, C.J. 2007. Possible Contribution of Blast Spores to the Oxidative Burst in the Infection Droplet on Rice Leaf. Acta Phytopathologica and Entomolgica Hungarica. 42(2):305-319.

Interpretive Summary: Plant diseases cause major losses to farmers each year. Better understanding of the biochemical basis for plant resistance to disease will lead to better strategies to improve plant health and reduce losses. In this paper we report the discovery that a microbe that causes plant disease can also produce reactive oxygen, a toxic substance that was previously thought to be produced only by plants to protect itself from microbes. Further studies will be needed to explain the role of this microbe produced toxic substance during disease. This information will be of use to plant scientists who are devising new strategies to improve disease resistance in plants.

Technical Abstract: The infection-induced overproduction of reactive oxygen species (ROS) in resistant plants is usually ascribed to the host. Here we tested the possible contribution of the parasite, the rice blast fungus to ROS production. Droplets of spore suspensions or water were kept on rice leaves or on plastic. After one day, superoxide radical and hydrogen peroxide were chemically assayed in drop diffusates. Similar measurements were done on diffusates of rice calli submerged in spore suspension or water. Negligible amounts of ROS were found in diffusates of plant tissues treated with water. In contrast, diffusates from tissues treated with spore suspensions had appreciable levels of ROS, usually higher in incompatible combinations than in compatible ones. However, diffusates of spores incubated on plastic produced ROS to an extent comparable to those of infected tissues. In diffusates of spores, O2- was found after their germination, and H2O2 was found after appressorium formation. Various fungal strains differed in ROS production. The results suggest that spores of the blast inoculum may contribute significantly to ROS production on rice leaves, at least, at early stages of the disease. This might be a factor of incompatibility suppressing a parasite and/or inducing defense responses of a host.