Induced epidermal permeability modulates resistance and susceptibility of wheat seedlings to herbivory by Hessian fly larvae

Salivary secretions of neonate Hessian fly larvae initiate a two-way exchange of molecules with their wheat host. Changes in properties of the leaf surface allow larval effectors to enter the plant where they trigger plant processes leading to resistance and delivery of defence molecules, or susceptibility and delivery of nutrients. To increase understanding of the host plant's response, the timing and characteristics of the induced epidermal permeability were investigated. Resistant plant permeability was transient and limited in area, persisting just long enough to deliver defence molecules before gene expression and permeability reverted to pre-infestation levels. The abundance of transcripts for GDSL-motif lipase/hydrolase, thought to contribute to cuticle reorganization and increased permeability, followed the same temporal profile as permeability in resistant plants. In contrast, susceptible plants continued to increase in permeability over time until the entire crown of the plant became a nutrient sink. Permeability increased with higher infestation levels in susceptible but not in resistant plants. The ramifications of induced plant permeability on Hessian fly populations are discussed

Reactive Oxygen Species Are Involved in Plant Defense against a Gall Midge[C][W][OA]

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 (Triticum aestivum) and rice (Oryza sativa) against Hessian fly (Mayetiola destructor) larvae. Rapid and prolonged accumulation of hydrogen peroxide (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 nonhost interactions with the larvae. No increase in accumulation of either H2O2 or superoxide was observed in wheat plants during compatible interactions. A global analysis revealed changes in the abundances of 250 wheat transcripts and 320 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 nonhost interactions, whereas the levels of these transcripts decreased in susceptible wheat during compatible interactions. The higher levels of class III peroxidase transcripts were associated with elevated enzymatic activity of peroxidases at the attack site in plants during incompatible and nonhost interactions. Overall, our data indicate that class III peroxidases may play a role in ROS generation in resistant wheat and nonhost rice plants during response to Hessian fly attacks