GENETIC ENHANCEMENT FOR RESISTANCE TO BIOTIC AND ABIOTIC STRESSES IN HARD WINTER WHEAT
Location: Hard Winter Wheat Genetics Research Unit
Title: Reactive Oxygen Species Are Involved in Plant Defense against a Gall Midge
Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 2009
Publication Date: February 1, 2010
Citation: Liu, X, Williams C. E., Nemacheck, J. A., Wang, H., Subramanyam, S., Zheng, C., Chen, M.-S. 2010. Reactive Oxygen Species are Involved in Plant Defense Against a Gall Midge. Plant Physiology. 152:985-999.
Interpretive Summary: Host plant resistance is the most effective and cost efficient means to control Hessian fly, a serious pest of wheat. However, the rapid development of new biotypes has made resistance in host plants short-lived, lasting for only 6-8 years for a specific resistance gene. A better understanding of plant resistance mechanisms is needed to develop more durable resistant wheat. This research investigated the potential role of reactive oxygen species (ROS) in plant defense against Hessian fly. We found that hydrogen peroxide, a major form of ROS, was accumulated to high levels at the feeding site in resistant wheat and in non-host rice plants following Hessian fly attack. Hydrogen peroxide was very toxic to fruit fly larvae, a related insect that belongs to the same order as Hessian fly. This research broadened our understanding of plant defense against different herbivores and provided a foundation for future research that may lead to more effective host plant resistance.
Reactive oxygen species (ROS) play a major role in plant defense against pathogens, but evidence for their role in defense against insects is still preliminary and inconsistent. In this study, we examined the potential role of ROS in defense of wheat and rice against Hessian fly (Mayetiola destructor) larvae, model systems to study gall midge – plant interactions. Rapid and prolonged accumulation of H2O2 was detected in wheat plants at the attack site during incompatible interactions. Increased accumulation of both H2O2 and superoxide was detected in rice plants during non-host interactions with the larvae. No increase in accumulation of either H2O2 or superoxide was observed in wheat plants during compatible interactions. The low concentration (LD50<0.05 µg/ml or 1.7 µM) of H2O2 required for lethality to Drosophila larvae suggested that the ROS accumulation at the attack site could cause toxicity to Hessian fly larvae. A global analysis revealed changes in the abundances of 243 wheat transcripts and 313 rice transcripts encoding proteins potentially involved in ROS homeostasis. A large number of transcripts encoded class III peroxidases that increased in abundance during both incompatible and non-host interactions, whereas the levels of these transcripts decreased in susceptible wheat during compatible interactions. The higher levels of class III peroxidase transcripts was associated with elevated enzymatic activity of peroxidases at the attack site in plants during incompatible and non-host interactions. These data indicated that class III peroxidases may play a major role in ROS generation in resistant wheat and non-host rice plants during response to Hessian fly attacks.