Molecular Crosstalk Between PAMP-Triggered Immunity and Photosynthesis

Heinrich-Heine University, Dusseldorf, Germany.
Molecular Plant-Microbe Interactions (Impact Factor: 3.94). 05/2012; 25(8):1083-92. DOI: 10.1094/MPMI-11-11-0301
Source: PubMed


The innate immune system allows plants to respond to potential pathogens in an appropriate manner while minimizing damage and energy costs. Photosynthesis provides a sustained energy supply and, therefore, has to be integrated into the defense against pathogens. Although changes in photosynthetic activity during infection have been described, a detailed and conclusive characterization is lacking. Here, we addressed whether activation of early defense responses by pathogen-associated molecular patterns (PAMPs) triggers changes in photosynthesis. Using proteomics and chlorophyll fluorescence measurements, we show that activation of defense by PAMPs leads to a rapid decrease in nonphotochemical quenching (NPQ). Conversely, NPQ also influences several responses of PAMP-triggered immunity. In a mutant impaired in NPQ, apoplastic reactive oxygen species production is enhanced and defense gene expression is differentially affected. Although induction of the early defense markers WRKY22 and WRKY29 is enhanced, induction of the late markers PR1 and PR5 is completely abolished. We propose that regulation of NPQ is an intrinsic component of the plant's defense program.

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    • "For example NPQ suppresses ROS formation and evidence shows that this can lead to plants being more palatable to herbivores (Jankanpaa et al. 2013). Recent work has suggested that activation of early defense reponses by pathogen –associated molecular patterns (PAMPS) triggers a temporary reduction in NPQ in order to permit and possibly as part of ROS mediated signalling and plant immunity (Göhre et al. 2012). "
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    • "However, in contrast to the expected increase in photosynthesis during virulent or avirulent pathogen infections, a marked decrease in this process has been observed (Göhre et al. 2012). This phenomenon was shown by evaluation of photosynthetic parameters, proteomics and transcriptomics assays (Zou et al. 2005; Göhre et al. 2012). It has been suggested that the decrease in photosynthesis during infections could be an active process of the plant defence program to limit C source accessibility for the pathogen or as a consequence of a prioritisation of metabolic processes in favour of defence reactions (Bolton 2009). "
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    • "This can be explained by different photoinhibition of PSII rates, which increased the levels of transcript genes involved in electron transport chain of photosystems (Cramer et al., 2007). The balance between light capture and energy use may be of great relevance for drought tolerance and possibly for immune response (Göhre et al., 2012). Tolerant genotype also exhibited a low enhanced expression of NCED2 involved in ABA biosynthesis. "
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