Phospholipases in Nitric Oxide-Mediated Plant Signaling

Nitro-oleic acid triggers ROS production via NADPH oxidase activation in plants: A pharmacological approach

Nitrated fatty acids (NO₂-FAs) are important signaling molecules in mammals. NO₂-FAs are formed by the addition reaction of nitric oxide- and nitrite-derived nitrogen dioxide with unsaturated fatty acid double bonds. The study of NO₂-FAs in plant systems constitutes an interesting and emerging area. The presence of NO₂-FA has been reported in olives, peas, rice and Arabidopsis. To gain a better understanding of the role of NO₂-FA on plant physiology, we analyzed the effects of exogenous application of nitro-oleic acid (NO₂-OA). In tomato cell suspensions we found that NO₂-OA induced reactive oxygen species (ROS) production in a dose-dependent manner via activation of NADPH oxidases, a mechanism that requires calcium entry from the extracellular compartment and protein kinase activation. In tomato and Arabidopsis leaves, NO₂-OA treatments induced two waves of ROS production, resembling plant defense responses. Arabidopsis NADPH oxidase mutants showed that NADPH isoform D (RBOHD) was required for NO₂-OA-induced ROS production. In addition, on Arabidopsis isolated epidermis, NO₂-OA induced stomatal closure via RBOHD and F. Altogether, these results indicate that NO₂-OA triggers NADPH oxidase activation revealing a new signaling role in plants.

Cues from chewing insects - the intersection of DAMPs, HAMPs, MAMPs and effectors

Chewing herbivores cause massive damage when crushing plant tissues with their mandibles, thus releasing a vast array of cues that may be perceived by the plant to mobilize defenses. Besides releasing damage cues in wounded tissues, herbivores deposit abundant cues from their saliva, regurgitant and feces that trigger herbivore specific responses in plants. Herbivores can manipulate the perception mechanisms and defense signals to suppress plant defenses by secreting effectors and/or by exploiting their associated oral microbes. Recent studies indicate that both the composition of herbivore cues and the plant's ability to recognize them are highly dependent upon the specific plant-herbivore system. There is a growing amount of work on identifying herbivore elicitors and effectors, but the most significant bottleneck in the discipline is the identification and characterization of plant receptors that perceive these herbivore-specific cues.