Plant responses to insect herbivory: interactions between photosynthesis, reactive oxygen species and hormonal signalling pathways

Abstract

Under herbivore attack plants mount a defence response characterized by the accumulation of secondary metabolites and inhibitory proteins. Significant changes are observed in the transcriptional profiles of genes encoding enzymes of primary metabolism. Such changes have often been interpreted in terms of a requirement for an increased investment of resources to 'fuel' the synthesis of secondary metabolites. While enhanced secondary metabolism undoubtedly exerts an influence on primary metabolism, accumulating evidence suggests that rather than stimulating photosynthesis insect herbivory reduces photosynthetic carbon fixation and this response occurs by a re-programming of gene expression. Within this context, reactive oxygen species (ROS) and reductant/oxidant (redox) signalling play a central role. Accumulating evidence suggests that ROS signalling pathways are closely interwoven with hormone-signalling pathways in plant-insect interactions. Here we consider how insect infestation impacts on the stress signalling network through effects on ROS and cellular redox metabolism with particular emphasis on the roles of ROS in the plant responses to phloem-feeding insects.

SWAPDT: A method for Short-time Withering Assessment of Probability for Drought Tolerance in Camellia sinensis validated by targeted metabolomics

“…There was a significant down regulation of the carbohydrate metabolites noted in the DT cultivars as compared to the DS cultivars (Figure 7). The photosynthetic pathway is the most affected when plants are subjected to abiotic stresses such as drought (Kerchev et al, 2012). This negatively impacts on primary metabolism, affecting metabolites such as sugars, sugar alcohols and amino acids.…”

Salix lapponum L. vs. phytophagous insects – an assessment of the risks and the reaction of plants

“…In our study, we found that the feeding of herbivores on S. lapponum leaves induced accumulation of H 2 O 2 very close to the area of damage. Similarly, other studies have provided direct evidence for H 2 O 2 accumulation following plant infestation by either chewing or piercing-sucking insects (Kerchev et al, 2012, and references therein). For example, a study concerning infestation of lima bean by the chewing caterpillar Spodoptera littoralis Boisd.…”

“…The magnitude of the insect herbivory effect on photosynthetic capacity is multifaceted, depending mostly on the type of feeding habits and the specificity of plant defense responses (Nabity et al, 2009). It has been found that plant genotypes that are capable to maintain photosynthesis under insect attack often exhibit greater resistance, which supports the hypothesis that insect-induced changes in photosynthesis are genetically programmed (Kerchev et al, 2012). In general, healthy plants have photosynthetic efficiency (F v /F m ) of 0.8-0.9, while plants suffering from stress have ratios of ca.…”

“…Among the indirect effects on physiological processes, photosynthesis disruption can have the most significant influence on plant growth and performance (Nabity et al, 2009). Moreover, several studies have revealed inhibition of photosynthesis following insect oviposition, even where eggs are laid on the leaf surface in the absence of tissue damage, which suggests that down-regulation of photosynthesis is a plant-driven response to the perception of stress rather than a secondary physiological response to tissue damage (Kerchev et al, 2012). It is well established that the emission of chlorophyll a fluorescence provides an indicator of the primary photochemistry of photosynthesis (Murchie & Lawson, 2013).…”

“…Photosynthesis disturbances that are often observed under insect attack are considered as the main cause of increased reactive oxygen species (ROS) accumulation and induction of oxidative stress (Kerchev et al, 2012). Therefore, the oxidative status of plants is an important strategy that enables plants to defend themselves against various biotic and abiotic stresses.…”